**Introduction**

The essential 12 chapters were accepted from the submitted materials, which were grouped in the next four sections. The second section, which includes gas biofuels, contains two chapters

tree (EFBOPT) for the production of second-generation bioethanol and Chapter 5 containing considerations in the field of high biomass/bagasse from sorghum and Bermuda grass as

Due to the generality of production and the degree of utilization, the fourth section on bio‐

tion methods, description of ultrasonic methods in the production and analysis of biodiesel

to the research on the nitrogen oxide emissions of B20-fueled engines and the final chapter of this section, which discusses the systems of modern bioreactors for the cultivation of al‐

The fifth section includes Chapter 11 defining the potential for the use of biofuels in Turkey and Chapter 12 covering the very prospective biorefinery technology in the field of produc‐ tion technology for biodegradable biomass-derived plastics. The last chapter, Chapter 13, goes somewhat beyond the thematic area of the book and defines the environmental condi‐ tions for obtaining synthetic gas from natural gas. This chapter has been included in the book, because in both our own research and literature data, it can be expected that synthesis

biofuel production and depending on the origin also for the production of effective and

thor Service Manager from IntechOpen Publishing House, for the patience, understanding and, most importantly, effective coordination of the complex publishing process of this book. I dedicate this book to my daughter Ewa, who stimulated and mobilized me to work on the edition of this book. I hope that Ewa's knowledge of her specialization, which is psychology,

esses of biofuels and other alternative fuels, which may be important for the development

and kinetics of transesterification processes. This section also contains Chapter

gae as raw materials for the production of second-generation biodiesel.

gas in the future, including waste biomass, may prove to be

adaptable alternative fuels.

Finally, on behalf of the authors and my own,

prospects and social acceptance of these energy carriers.

will allow us in the future to develop

example of Mexico and the very important issues for the use of biomethane in transport.

2 and 3) covering the production processes of biogas from waste substances on the

4 on the possibility of using waste fruit palm

a review of catalytic transesterifica‐

a universal raw material for

**Prof. Krzysztof Biernat** Automotive Industry Institute

Warsaw, Poland

I would like to thank Mrs. Maja Bozicevic, Au‐

a book on the psychological determinants of the proc‐

a

9 dedicated

(Chapters

VIII Preface

The third section is represented by Chapter

raw material for the production of second-generation bioethanol.

diesel includes Chapters 6–10, which include, inter alia,

**Chapter 1**

**Provisional chapter**

**Introductory Chapter: Prospective Biofuels**

mixture meets all normative requirements for conventional diesel fuels.

**Introductory Chapter: Prospective Biofuels**

DOI: 10.5772/intechopen.78663

The development and modifications of the drives of modern engines therefore require appropriate fuels for these drives, so that the main requirements set out above are met. These requirements are defined by engineers and vehicle manufacturers, while guaranteeing the durability and reliability of engines powered by appropriate fuels. To ensure the correct quality of fuels for spark-ignition and self-ignition engines meeting the requirements of internal combustion engines and environmental protection, leading global car concerns have established World-Wide Fuel Charter (WWFC) [1, 2]. Due to the increasingly stringent environmental requirements, the fifth edition of the WWFC was introduced, which introduced, in addition to the current four, additional, fifth categories of both motor gasolines and diesel oils. In the fifth edition of the WWFC, in the same way for all five motor gasolines categories, it is permissible to add up to 10% (v/v) of ethanol, with the ban on methanol being sustained, and for diesel oils, the permissible addition of up to 5% (v/v) FAME to fuels in categories 1–4, while in the top category 5, the content of this biocomponent is not allowed. In Category 5 of diesel oils, it is permissible to use other biocomponents originating from "hydrotreated vegetable oil" (HVO) and "biomass to liquid" (BtL) processes, provided that the resulting

It is anticipated that the prospective raw materials for the production of biofuels will be all waste substances (biodegradable at the beginning), including waste biomass (lignocellulosic feedstock) and in the long-term waste carbon dioxide, and even water vapor. Due to environmental conditions, we should carefully approach energy crops as a raw material.

> © 2016 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

© 2018 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use,

distribution, and reproduction in any medium, provided the original work is properly cited.

Additional information is available at the end of the chapter

Krzysztof BiernatAdditional information is available at the end of the chapter

http://dx.doi.org/10.5772/intechopen.78663

Krzysztof Biernat

**1. Introduction**

**2. Types of biofuels**

#### **Chapter 1 Provisional chapter**

#### **Introductory Chapter: Prospective Biofuels Introductory Chapter: Prospective Biofuels**

DOI: 10.5772/intechopen.78663

## Krzysztof Biernat

Additional information is available at the end of the chapter Krzysztof BiernatAdditional information is available at the end of the chapter

http://dx.doi.org/10.5772/intechopen.78663

#### **1. Introduction**

The development and modifications of the drives of modern engines therefore require appropriate fuels for these drives, so that the main requirements set out above are met. These requirements are defined by engineers and vehicle manufacturers, while guaranteeing the durability and reliability of engines powered by appropriate fuels. To ensure the correct quality of fuels for spark-ignition and self-ignition engines meeting the requirements of internal combustion engines and environmental protection, leading global car concerns have established World-Wide Fuel Charter (WWFC) [1, 2]. Due to the increasingly stringent environmental requirements, the fifth edition of the WWFC was introduced, which introduced, in addition to the current four, additional, fifth categories of both motor gasolines and diesel oils. In the fifth edition of the WWFC, in the same way for all five motor gasolines categories, it is permissible to add up to 10% (v/v) of ethanol, with the ban on methanol being sustained, and for diesel oils, the permissible addition of up to 5% (v/v) FAME to fuels in categories 1–4, while in the top category 5, the content of this biocomponent is not allowed. In Category 5 of diesel oils, it is permissible to use other biocomponents originating from "hydrotreated vegetable oil" (HVO) and "biomass to liquid" (BtL) processes, provided that the resulting mixture meets all normative requirements for conventional diesel fuels.

#### **2. Types of biofuels**

It is anticipated that the prospective raw materials for the production of biofuels will be all waste substances (biodegradable at the beginning), including waste biomass (lignocellulosic feedstock) and in the long-term waste carbon dioxide, and even water vapor. Due to environmental conditions, we should carefully approach energy crops as a raw material.

© 2016 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. © 2018 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

The modern state of knowledge defines as relatively safe crops (cultivations) of Jatropha, Arnica, halophytes, and algae, which can be raw materials for biofuels. The need to look for new raw materials necessary for the production of biofuels (as well as bioliquids—energy carriers for industrial applications) is particularly important in European countries. In these countries, the need to introduce biofuels has been legally sanctioned, and at the same time, there has been a development of waste biomass recycling technology. Taking into account significant environmental conditions, limiting the use of all biomass for industrial purposes, it is necessary, especially in European countries, to import biofuels and raw materials for their production.

• biogas as synthetically produced natural gas—biomethane (SNG), obtained as a result of lignocellulose gasification processes, and appropriate synthesis as a result of agricultural

• biohydrogen obtained as a result of gasification of lignocellulose and synthesis of gasifica-

As part of the developed documents characterizing further perspectives in the development of biofuels, it was also proposed to separate the next generation of biofuels, i.e., the third one, which would contain biofuels obtained from genetically modified biomass, in order to facilitate conversion processes with known technologies. The fourth category would include biofuels produced from biomass, whose genetic modification would additionally increase the absorptivity of carbon dioxide in the photosynthesis process. In the available literature, biofuels obtained from algae are very often included in the third generation of biofuels. It is definitely not correct, because the division of biofuels into the third and fourth generation has been clearly defined by the former Directorate General for Energy and Transport of the European Commission [9]. Based on previous experience, it turned out that there is a need to develop more efficient ways to obtain biofuels, which resulted in the separation of third-generation biofuels, obtained by similar methods as second-generation fuels, but from a properly modified raw material. The raw material for the production of third-generation biofuels should be made of biomass, modified at the stage of cultivation, among others by means of molecular biological techniques. The purpose of these modifications is to improve the conversion of biomass to biofuels by, for example, growing trees with low lignin content, growing crops with enzymes built in. Biofuels that are completely obtained by biochemical methods such as biohydrogen, biomethanol, or biobutanol can also be included in this gen-

A prospective fourth generation of biofuels has been separated due to the need to close the carbon dioxide balance or to eliminate its impact on the environment. Therefore, the fourthgeneration biofuel technologies should take into account carbon capture and storage (CCS) processes, i.e., carbon capture and storage at the stage of raw materials and production technologies of these biofuels. So, raw materials for the production of biofuels of this generation

technologies used must take into account the uptake of carbon dioxide in appropriate geological formations by bringing to the carbonate stage or storage in oil and gas workings. To avoid creating further divisions of biofuels that may arise in the future, the International Energy Agency proposes to group these fuels as conventional ("conventional biofuels") and future-oriented ("advanced biofuels"). The proposed division of biofuels by IEA is increas-

Research into the processes of obtaining substitutes for previously used fuels, referred to as "alternative fuels" for motor gasolines, diesel fuels, and even aviation fuels is being conducted intensively in the world. An alternative gas fuel for SI engines is already manufactured in

during cultivation, and the

Introductory Chapter: Prospective Biofuels http://dx.doi.org/10.5772/intechopen.78663 5

can be plants with increased, even genetically assimilated, CO<sup>2</sup>

biogas, landfill, and sewage sludge treatment processes [8];

tion products or as a result of biochemical processes.

eration of biofuels.

ingly used.

**3. Perspective biofuels**

From many tests, including engine tests, it is clear that use as additives (first-generation biocomponents) is not beneficial for the operation of combustion engines, and fuels with biocomponents cannot be practically stored, and in some cases, the use of biofuels. The first generation not only does not close the balance of carbon dioxide, but unfortunately it is characterized by the positive emissivity of this gas. In addition, the use of food for energy purposes is considered to be unethical ("food competition"), and in turn, energy crops can cause disturbances in "biodiversity" and the occurrence of scarcity of land for cultivation for the agri-food industry, the so-called "land hunger" ("ground competition"). Therefore, it should be considered technical, operational, and environmental, as the right way to replace first-generation biofuels with second-generation and higher-generation biofuels [3–7].

In the second generation of biofuels, as before, the following fuels are located:


As part of the developed documents characterizing further perspectives in the development of biofuels, it was also proposed to separate the next generation of biofuels, i.e., the third one, which would contain biofuels obtained from genetically modified biomass, in order to facilitate conversion processes with known technologies. The fourth category would include biofuels produced from biomass, whose genetic modification would additionally increase the absorptivity of carbon dioxide in the photosynthesis process. In the available literature, biofuels obtained from algae are very often included in the third generation of biofuels. It is definitely not correct, because the division of biofuels into the third and fourth generation has been clearly defined by the former Directorate General for Energy and Transport of the European Commission [9]. Based on previous experience, it turned out that there is a need to develop more efficient ways to obtain biofuels, which resulted in the separation of third-generation biofuels, obtained by similar methods as second-generation fuels, but from a properly modified raw material. The raw material for the production of third-generation biofuels should be made of biomass, modified at the stage of cultivation, among others by means of molecular biological techniques. The purpose of these modifications is to improve the conversion of biomass to biofuels by, for example, growing trees with low lignin content, growing crops with enzymes built in. Biofuels that are completely obtained by biochemical methods such as biohydrogen, biomethanol, or biobutanol can also be included in this generation of biofuels.

A prospective fourth generation of biofuels has been separated due to the need to close the carbon dioxide balance or to eliminate its impact on the environment. Therefore, the fourthgeneration biofuel technologies should take into account carbon capture and storage (CCS) processes, i.e., carbon capture and storage at the stage of raw materials and production technologies of these biofuels. So, raw materials for the production of biofuels of this generation can be plants with increased, even genetically assimilated, CO<sup>2</sup> during cultivation, and the technologies used must take into account the uptake of carbon dioxide in appropriate geological formations by bringing to the carbonate stage or storage in oil and gas workings. To avoid creating further divisions of biofuels that may arise in the future, the International Energy Agency proposes to group these fuels as conventional ("conventional biofuels") and future-oriented ("advanced biofuels"). The proposed division of biofuels by IEA is increasingly used.

#### **3. Perspective biofuels**

The modern state of knowledge defines as relatively safe crops (cultivations) of Jatropha, Arnica, halophytes, and algae, which can be raw materials for biofuels. The need to look for new raw materials necessary for the production of biofuels (as well as bioliquids—energy carriers for industrial applications) is particularly important in European countries. In these countries, the need to introduce biofuels has been legally sanctioned, and at the same time, there has been a development of waste biomass recycling technology. Taking into account significant environmental conditions, limiting the use of all biomass for industrial purposes, it is necessary, especially in European countries, to import biofuels and raw materials for their

From many tests, including engine tests, it is clear that use as additives (first-generation biocomponents) is not beneficial for the operation of combustion engines, and fuels with biocomponents cannot be practically stored, and in some cases, the use of biofuels. The first generation not only does not close the balance of carbon dioxide, but unfortunately it is characterized by the positive emissivity of this gas. In addition, the use of food for energy purposes is considered to be unethical ("food competition"), and in turn, energy crops can cause disturbances in "biodiversity" and the occurrence of scarcity of land for cultivation for the agri-food industry, the so-called "land hunger" ("ground competition"). Therefore, it should be considered technical, operational, and environmental, as the right way to replace

first-generation biofuels with second-generation and higher-generation biofuels [3–7].

• bioethanol, biobutanol, and mixtures of higher alcohols and their derivatives obtained as a result of advanced processes of hydrolysis and fermentation of lignocellulose derived from

• synthetic biofuels that are products of biomass processing through gasification and appropriate synthesis for liquid fuel components in BtL processes and resulting from the processing of biodegradable industrial and municipal waste, including carbon dioxide in WtL

• fuels for self-ignition engines derived from the processing of lignocellulose from biomass in Fischer-Tropsch processes, including synthetic biodiesel derived from the composition

• biomethanol obtained as a result of lignocellulose transformation processes, including

• biodimethylether (bio-DME) obtained in thermochemical processes of biomass processing, including biomethanol, biogas, and synthesis gases being derivatives of biomass transfor-

• biodiesel, as a biofuel or fuel component for self-ignition engines obtained as a result of hydrogen refining (hydrogenation) of waste, derived from waste vegetable oils and animal

• biodimethylfuran (bio-DMF) derived from sugar processing processes, including cellulose in thermo- and biochemical processes, derived from the processing of waste raw materials;

Fisher-Tropsch synthesis and also using waste carbon dioxide;

In the second generation of biofuels, as before, the following fuels are located:

biomass (excluding raw materials for food);

production.

4 Biofuels - State of Development

processes;

of lignocellulosic products;

mation processes;

fats;

Research into the processes of obtaining substitutes for previously used fuels, referred to as "alternative fuels" for motor gasolines, diesel fuels, and even aviation fuels is being conducted intensively in the world. An alternative gas fuel for SI engines is already manufactured in the world, DME (dimethylether) or bio-DME, where DME can be produced from coal, and bio-DME from lignocellulosic biomass, and even from waste substances. Biofuels should also be included in the group of alternative fuels. It is planned to purify biogas to almost pure biomethane and compress it to form gaseous fuel with similar qualitative characteristics as compressed natural gas (CNG). In the field of liquid fuels, technologies for the production of second-generation bioethanol from lignocelluloses (waste biomass or specific energy crops) or from waste substances are being implemented. Also tested is biobutanol from fermentation processes and DMF (dimethylfuran) obtained from cellulose and starch, also considered solar fuels, obtained in the processes of thermal decomposition of biomass or waste. The processes of converting biomass into liquid fuels are referred to as "biomass to liquid" processes (BtL), and obtained from waste—"waste to liquid" processes (WtL). Alternative fuels are also considered, being properly composed mixtures of synthetic hydrocarbons obtained from various raw materials—so-called XtL processes. A prospective raw material may be synthesis gas obtained from very different thermal and thermocatalytic processes of waste substances, including biomass and energy crops, and also, what is new, derived from the synthesis of water vapor and carbon dioxide. Various types of hydrocarbons can be obtained from syngas whose compositions will correspond to the composition of gasolines, diesel fuels, or aviation fuels. Synthesis gas, in the light of recent studies, the results of which are already implemented on a demonstration scale, can also be subjected to a fermentation process, leading to the production of bioethanol, and hydrocarbons from C2 to C5. In the perspective, hydrogen or biogas obtained from synthesis gas or other biomass transformation processes is referred to as a universal energy carrier, but it is envisaged to use it as a carrier in fuel cells (for example, supplying electric cars). The future of alternative fuels in the world up to 2050 was outlined in a document prepared by the International Energy Agency ("Technology Roadmap—Biofuels for Transport"). The document also presents the current division and prospects for the development of biofuels, as shown in **Figure 1**.

• **Fuels from BtL processes** (synthetic hydrocarbon compositions), obtained by rapid pyrolysis, biomass heating to a temperature between 400 and 600°C, followed by rapid cooling, whereby unstable compounds can be converted into liquids (HTU process) as a fuel HTU-diesel or deoxidized (HDO process), distilled, and refined for fuel compositions. The remainder of the so-called bio-char (charcoal) as a by-product can be used as a solid fuel, or

Introductory Chapter: Prospective Biofuels http://dx.doi.org/10.5772/intechopen.78663 7

• **Diesel oil from processes BtL**, so-called FT-diesel, obtained by conversion to synthesis gas and catalytic Fischer-Tropsch synthesis (FT) in a wide range of liquid hydrocarbons,

• **Hydrotreated vegetable oil (HVO)** as fuel for self-ignition engines or fuel oil produced by hydrogenation of vegetable oils or animal fats (nonfood and waste). The first large plants were launched in Finland and Singapore, but the processes have not yet been fully

• **Cellulosic bioethanol** produced from lignocellulosic raw materials by biochemical conversion of cellulose and hemicellulose leading to the fermentation of sugars (IEA, 2008a, [16]). Cellulose ethanol has a better energy balance in terms of greenhouse gas emissions and

• **Biogas** obtained through anaerobic digestion of raw materials such as organic waste, animal waste, and sewage sludge, and/or energy plants. Purified for biomethane (SNG) by

**Figure 1.** The division of biofuels and their advancement in production according to IEA [10].

used as a means for carbon sequestration and soil fertilization;

including synthetic diesel and JET biofuels;

land-use requirements than starch ethanol;

commercialized;

An analogous document, "Innovation Outlook: Advanced Liquid Biofuels," was developed by the International Renewable Energy Agency (IRENA) in 2016, where the state and prospects for biofuels were also characterized with the current TRL levels. The division of biofuels according to IRENA is shown in **Figure 2**.

Therefore, taking into account environmental, operational, and logistic conditions, it is necessary to gradually pass biofuel production processes from processes using typical agro-food products to biomass, mainly waste—BtL processes, waste substances—"waste to liquid" processes (WtL), vegetable fat waste, and animal oils (frying oils), nonedible vegetable oils—HVO processes, production of biomethane from biogas using waste carbon dioxide for industrial algae breeding (microalgae). The future is the work started in the USA on the production of "solar fuels,", furan fuels, and work on the gasification of various waste substances in XtL processes, followed by the production of so-called "synthetic hydrocarbons," i.e., biorefinery processes also in the beginning become the main European program "Bio-economy for Europe."

Taking into account the demand for biofuels that meet the requirements of future sources of propulsion for means of transport, including air transport, as well as limiting carbon dioxide emissions, in terms of future fuels, the following biofuels will be preferred along with the technological paths of their production [1, 3–7]:


• **Biogas** obtained through anaerobic digestion of raw materials such as organic waste, animal waste, and sewage sludge, and/or energy plants. Purified for biomethane (SNG) by

the world, DME (dimethylether) or bio-DME, where DME can be produced from coal, and bio-DME from lignocellulosic biomass, and even from waste substances. Biofuels should also be included in the group of alternative fuels. It is planned to purify biogas to almost pure biomethane and compress it to form gaseous fuel with similar qualitative characteristics as compressed natural gas (CNG). In the field of liquid fuels, technologies for the production of second-generation bioethanol from lignocelluloses (waste biomass or specific energy crops) or from waste substances are being implemented. Also tested is biobutanol from fermentation processes and DMF (dimethylfuran) obtained from cellulose and starch, also considered solar fuels, obtained in the processes of thermal decomposition of biomass or waste. The processes of converting biomass into liquid fuels are referred to as "biomass to liquid" processes (BtL), and obtained from waste—"waste to liquid" processes (WtL). Alternative fuels are also considered, being properly composed mixtures of synthetic hydrocarbons obtained from various raw materials—so-called XtL processes. A prospective raw material may be synthesis gas obtained from very different thermal and thermocatalytic processes of waste substances, including biomass and energy crops, and also, what is new, derived from the synthesis of water vapor and carbon dioxide. Various types of hydrocarbons can be obtained from syngas whose compositions will correspond to the composition of gasolines, diesel fuels, or aviation fuels. Synthesis gas, in the light of recent studies, the results of which are already implemented on a demonstration scale, can also be subjected to a fermentation process, leading to the production of bioethanol, and hydrocarbons from C2 to C5. In the perspective, hydrogen or biogas obtained from synthesis gas or other biomass transformation processes is referred to as a universal energy carrier, but it is envisaged to use it as a carrier in fuel cells (for example, supplying electric cars). The future of alternative fuels in the world up to 2050 was outlined in a document prepared by the International Energy Agency ("Technology Roadmap—Biofuels for Transport"). The document also presents the current division and prospects for the devel-

An analogous document, "Innovation Outlook: Advanced Liquid Biofuels," was developed by the International Renewable Energy Agency (IRENA) in 2016, where the state and prospects for biofuels were also characterized with the current TRL levels. The division of biofuels

Therefore, taking into account environmental, operational, and logistic conditions, it is necessary to gradually pass biofuel production processes from processes using typical agro-food products to biomass, mainly waste—BtL processes, waste substances—"waste to liquid" processes (WtL), vegetable fat waste, and animal oils (frying oils), nonedible vegetable oils—HVO processes, production of biomethane from biogas using waste carbon dioxide for industrial algae breeding (microalgae). The future is the work started in the USA on the production of "solar fuels,", furan fuels, and work on the gasification of various waste substances in XtL processes, followed by the production of so-called "synthetic hydrocarbons," i.e., biorefinery processes also in the beginning become the main European program "Bio-economy for

Taking into account the demand for biofuels that meet the requirements of future sources of propulsion for means of transport, including air transport, as well as limiting carbon dioxide emissions, in terms of future fuels, the following biofuels will be preferred along with the

opment of biofuels, as shown in **Figure 1**.

6 Biofuels - State of Development

according to IRENA is shown in **Figure 2**.

technological paths of their production [1, 3–7]:

Europe."

**Figure 1.** The division of biofuels and their advancement in production according to IEA [10].

removing carbon dioxide (CO<sup>2</sup> ) and hydrogen sulfide (H<sup>2</sup> S), it can be a motor fuel or a hydrogen source, also for cell fuel;

ensures greater reduction of greenhouse gas emissions. They can also be obtained as a result of the decomposition of water (steam) and the use of carbon dioxide to produce synthesis gas, catalytically converted to fuel fractions. The production of these fuels may

• **Biorefinery systems** [13] for the production of liquid fuels and chemical intermediates. These processes are preferred in each of the five "value chains" set started in 2014. Bioeconomy for Europe, as a prospective, waste-free, biofuels, biomaterials

In the area of the most promising raw materials for future biofuels, taking into account the

niknik, Jatropha, and halophytes is preferred. To increase the amount of possible biomass resources to be used, technologies such as sunless (dark) photosynthesis and marine membrane systems for the production of algae, and technologies for the production of biometha-

The future of biofuels as alternative energy carriers for transport and bioliquids for stationary devices will depend on many factors. The main determinant is the availability of raw materials and the efficiency of both production technology and direct exploitation and, most importantly, the reduction of greenhouse gas emissions, including mainly carbon dioxide, throughout the life cycle assessment cycle (LCA). Taking into account the degree of development of various biomass waste processing technologies, it seems that the most effective and efficient gasification technologies are not only waste biomass for biofuel production in BtL processes but also gasification processes for industrial waste, mainly plastics leading to the production of alternative fuels in WtL processes [14], which prefers to jointly run XtL processes as processes significantly affecting the improvement of the environment. It seems, therefore, that future synthesis gas can be treated as a universal energy carrier. The confirmation of this thesis may be synthesis gas fermentation processes [13] enabling the production of bioethanol and other C2 to C5 hydrocarbons, i.e., acetic acid, isopropanol, dimethylketone, 2,3-butenediol, butane, isobutane, succinic acid, as well as isoprene structures important in the processes of economy on a closed circuit. In the field of alternative fuel production, with significant co-operation of the author's team, a patented thermolysis technology for plastic waste has been developed, which under atmospheric pressure conditions allows to obtain hydrocarbon fractions that can meet components of both motor gasolines and diesel oils compliant with the quality requirements of European fuel standards as "drop in alternative fuels" [15]. The catalyzed technology for producing synthesis gas from waste carbon dioxide and water vapor, which also has a significant negative impact on climate change, can also be considered as prospective. Therefore, one should strive to develop effective technologies of gasification processes of any waste raw materials, of course with regard to biomass, to obtain energy carriers adaptable by modern engines, both transport and stationary destination.

emissions, cultivation of algae,

Introductory Chapter: Prospective Biofuels http://dx.doi.org/10.5772/intechopen.78663 9

also include so-called "artificial leaf";

nol as a raw material are also being developed.

so-called "land hunger" and requirements for reducing CO<sup>2</sup>

(biochemicals).

**4. Conclusion**


**Figure 2.** Division and level of technological readiness of biofuels according to IRENA [11].

ensures greater reduction of greenhouse gas emissions. They can also be obtained as a result of the decomposition of water (steam) and the use of carbon dioxide to produce synthesis gas, catalytically converted to fuel fractions. The production of these fuels may also include so-called "artificial leaf";

• **Biorefinery systems** [13] for the production of liquid fuels and chemical intermediates. These processes are preferred in each of the five "value chains" set started in 2014. Bioeconomy for Europe, as a prospective, waste-free, biofuels, biomaterials (biochemicals).

In the area of the most promising raw materials for future biofuels, taking into account the so-called "land hunger" and requirements for reducing CO<sup>2</sup> emissions, cultivation of algae, niknik, Jatropha, and halophytes is preferred. To increase the amount of possible biomass resources to be used, technologies such as sunless (dark) photosynthesis and marine membrane systems for the production of algae, and technologies for the production of biomethanol as a raw material are also being developed.

#### **4. Conclusion**

removing carbon dioxide (CO<sup>2</sup>

8 Biofuels - State of Development

hydrogen source, also for cell fuel;

its disadvantages as a component fuel;

) and hydrogen sulfide (H<sup>2</sup>

• **Dimethyl ether (bio-DME)** as a gaseous fuel for self-ignition engines, obtained from methanol in the process of catalytic dehydration, from synthesis gas by gasification of lignocellulose and other biomass. The production of bio-DME from biomass gasification is in

• **Biobutanol** with higher energy density and more favorable than ethanol in motor gasolines (MG). It can be distributed via the existing BS network. Biobutanol can be produced by fermenting sugars with *Clostridium acetobutylicum*. Demonstration plants operate in

• **Furan fuels**, for which polysaccharides of the type cellulose and starch, constitute a raw material, obtained in defragmentation processes of multisugar chains leading to glucose, then converted into fructose, by isomerization using enzymatic catalysts. Fructose in the dehydration process changes into 5-hydroxymethylfurfural (HMF), which in the process of hydrogenolysis, in the presence of a copper-ruthenium catalyst, is converted into DMF (dimethylfuran), a fuel for spark-ignition engines with advantages over ethanol, without

• **Solar fuels** [12] obtained by gasification of biomass for syngas using heat generated by the concentration of solar energy, which potentially improves conversion efficiency and

a demonstration phase (September 2010 in Sweden, Chemrec);

Germany and the USA, while others are under construction;

**Figure 2.** Division and level of technological readiness of biofuels according to IRENA [11].

S), it can be a motor fuel or a

The future of biofuels as alternative energy carriers for transport and bioliquids for stationary devices will depend on many factors. The main determinant is the availability of raw materials and the efficiency of both production technology and direct exploitation and, most importantly, the reduction of greenhouse gas emissions, including mainly carbon dioxide, throughout the life cycle assessment cycle (LCA). Taking into account the degree of development of various biomass waste processing technologies, it seems that the most effective and efficient gasification technologies are not only waste biomass for biofuel production in BtL processes but also gasification processes for industrial waste, mainly plastics leading to the production of alternative fuels in WtL processes [14], which prefers to jointly run XtL processes as processes significantly affecting the improvement of the environment. It seems, therefore, that future synthesis gas can be treated as a universal energy carrier. The confirmation of this thesis may be synthesis gas fermentation processes [13] enabling the production of bioethanol and other C2 to C5 hydrocarbons, i.e., acetic acid, isopropanol, dimethylketone, 2,3-butenediol, butane, isobutane, succinic acid, as well as isoprene structures important in the processes of economy on a closed circuit. In the field of alternative fuel production, with significant co-operation of the author's team, a patented thermolysis technology for plastic waste has been developed, which under atmospheric pressure conditions allows to obtain hydrocarbon fractions that can meet components of both motor gasolines and diesel oils compliant with the quality requirements of European fuel standards as "drop in alternative fuels" [15]. The catalyzed technology for producing synthesis gas from waste carbon dioxide and water vapor, which also has a significant negative impact on climate change, can also be considered as prospective. Therefore, one should strive to develop effective technologies of gasification processes of any waste raw materials, of course with regard to biomass, to obtain energy carriers adaptable by modern engines, both transport and stationary destination.

#### **Author details**

#### Krzysztof Biernat

Address all correspondence to: k.biernat@pimot.eu

Department of Fuel and Bioeconomy, Automotive Industry Institute, Warsaw, Poland

[12] Gray BH. Solar Fuel. Engineering & Science; 1997;**3**:28-33

Biofuels Research Advisory Council

[13] Biernat K, Grzelak PL. Biorefinery system as an element of sustainable development, Chapter 20. In: Biernat K, editor. Biofuels—Status and Perspective. Rijeka: InTech; 2015

Introductory Chapter: Prospective Biofuels http://dx.doi.org/10.5772/intechopen.78663 11

[14] Samson-Bręk I, Biernat K. Processing of municipal waste and plastic for liquid fuels— WtL technology. Silniki Spalinowe; **1, 2012**(148):131. (Combustion Engines)

[15] Biofuels in the European Vision, a Vision 2030 and Beyond. Final Draft Report of the

[16] World Energy Outlook, International Energy Agency, OECD/IEA; 2008

#### **References**


[12] Gray BH. Solar Fuel. Engineering & Science; 1997;**3**:28-33

**Author details**

10 Biofuels - State of Development

Krzysztof Biernat

**References**

Address all correspondence to: k.biernat@pimot.eu

[1] World-Wide Fuel Charter. 5th ed. September 2013

Energia (Clean Energy). October 2010;**10**:25-28

biofuels in the world", "Liquid fuels")

and Sustainability. Rijeka: InTech; 2013

Storage Stability of Fuels. Rijeka: InTech; 2015

Rijeka: InTech; 2014

Biofuels; IRENA; 2016

Paris; 2011

Department of Fuel and Bioeconomy, Automotive Industry Institute, Warsaw, Poland

Spalinowe 2012 ('Combustion Engines'). Chemik. 2012;**66**(11):1178-1189

tion technology). Czysta Energia (Clean Energy). November 2010;**11**:33-36

[2] Rostek E, Biernat K. Analysis of the Quality Parameters of Selected Motor Biofuels Taking into Account the Current Requirements of the Worldwide Fuel Charter. Silniki

[3] Biernat K. Biopaliwa—Definicje i wymagania obowiązujace w Unii Europejskiej; (Biofuels—Definitions and requirements in force in the European Union). Czysta

[4] Biernat K. Rozwój technologii wytwarzania biopaliw. (Development of biofuel produc-

[5] Biernat K. Środowiskowe i energetyczne uwarunkowania technologii biopaliwowych. Warsaw: Wydawnictwo Forum Partnerstwa Regionalnego; January 2011. (Environmental and energy determinants of biofuel technologies. Regional Partnership Forum Publisher)

[6] Biernat K. Uwarunkowania eksploatacyjne i dystrybucyjne biopaliw w świecie. In: Paliwa Płynne. Vol. 7. 2011. pp. 39-43. ("Operational and distribution conditions for

[7] Biernat K, Malinowski A, Gnat M. The possibility of future biofuels using waste carbon dioxide and solar energy, Chapter 5. In: Fang Z, editor. Biofuels—Economy, Environment

[8] Malinowski A, Czarnocka J, Biernat K. An analysis physico-chemical properties of the next generation biofuels and their correlation with the requirements of diesel engine, Chapter 16. In: Fang Z, editor. Biodiesel—Feedstock, Production and Applications.

[9] Biernat K. Biofuels in storage and operating condition, Chapter 3. In: Biernat K, editor.

[10] Tanako N et al. Technology Roadmap. Biofuels for Transport. Published by OECE/IEA,

[11] AlbertsG, AyusoM, BauenA, BoshellF, ChudziakC, GebauerJP, GermanL, KaltschmittM, Nattrass L, Ripken RP. Taylor R, Wagner H. Innovation Outlook: Advanced Liquid


**Section 2**

**Biogas and Biomethane**

## **Biogas and Biomethane**

**Chapter 2**

**Provisional chapter**

**The Potential for Biogas Production from Agriculture**

**The Potential for Biogas Production from Agriculture** 

An important objective of the Mexican Energy National Strategy (ENS) is to produce around 35% of energy from clean technologies in 2024. This goal implies challenges from scientific and technologic perspectives. Besides solar and wind energies, different initiatives have been implemented to promote biofuels, mainly, biodiesel, bioethanol and biogas. Agriculture and livestock wastes are being used as biogas source to produce energy in small and medium scale. Also, some industries use biogas to provide a part of the energy required in their processes. But in general, the potential of biomethane production is not well seized yet. In the context of the ENS, biogas should be considered as an important topic due to the existence of several economical activities producing a lot of organic wastes. In this document, an analysis of the biogas from agricultural wastes is performed in order to identify the current status and opportunities for the next years.

The main sources of energy in Mexico are fossil fuels since there are, in some regions of the country, important reserves of oil, natural gas and even shale gas. However, from some years ago, a recurrent concern is the depletion of fossil fuels and the necessity of alternatives to

> © 2016 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

© 2018 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use,

distribution, and reproduction in any medium, provided the original work is properly cited.

DOI: 10.5772/intechopen.75457

**Wastes in Mexico**

**Wastes in Mexico**

Lourdes Diaz Jimenez

Lourdes Diaz Jimenez

**Abstract**

**1. Introduction**

**1.1. Objective of this study**

provide the increasing energy demand.

Salvador Carlos Hernandez and

Salvador Carlos Hernandez and

http://dx.doi.org/10.5772/intechopen.75457

Additional information is available at the end of the chapter

Additional information is available at the end of the chapter

**Keywords:** waste to methane, biofuel, agri-waste

#### **The Potential for Biogas Production from Agriculture Wastes in Mexico The Potential for Biogas Production from Agriculture Wastes in Mexico**

DOI: 10.5772/intechopen.75457

Salvador Carlos Hernandez and Lourdes Diaz Jimenez Salvador Carlos Hernandez and Lourdes Diaz Jimenez

Additional information is available at the end of the chapter Additional information is available at the end of the chapter

http://dx.doi.org/10.5772/intechopen.75457

#### **Abstract**

An important objective of the Mexican Energy National Strategy (ENS) is to produce around 35% of energy from clean technologies in 2024. This goal implies challenges from scientific and technologic perspectives. Besides solar and wind energies, different initiatives have been implemented to promote biofuels, mainly, biodiesel, bioethanol and biogas. Agriculture and livestock wastes are being used as biogas source to produce energy in small and medium scale. Also, some industries use biogas to provide a part of the energy required in their processes. But in general, the potential of biomethane production is not well seized yet. In the context of the ENS, biogas should be considered as an important topic due to the existence of several economical activities producing a lot of organic wastes. In this document, an analysis of the biogas from agricultural wastes is performed in order to identify the current status and opportunities for the next years.

**Keywords:** waste to methane, biofuel, agri-waste

#### **1. Introduction**

#### **1.1. Objective of this study**

The main sources of energy in Mexico are fossil fuels since there are, in some regions of the country, important reserves of oil, natural gas and even shale gas. However, from some years ago, a recurrent concern is the depletion of fossil fuels and the necessity of alternatives to provide the increasing energy demand.

From some years ago, renewable sources are considered as a real alternative to deal with the society requirements. In 2010, the National Strategy for Energy (NSE) has been designed in order to state directives concerning the generation and management of the energy. An important objective of this strategy is to produce around 35% of energy from clean technologies in 2024. This goal implies challenges from scientific and technologic perspectives. Besides solar and wind energies, different initiatives have been implemented to promote biofuels, mainly, biodiesel, bioethanol and biogas. Agriculture and livestock wastes are being used as biogas source to produce energy in small and medium scale. Also, some industries use biogas to provide a part of the energy required in their processes. But, in general, the potential of biomethane production is not well seized yet. In the context of the ENS, biogas should be considered as an important topic due to the existence of several economical activities producing a lot of organic wastes.

stability; it is very sensitive to variations in the operating conditions such as: pH, temperature, overload on substrate concentration, etc. Then, these two stages receive special attention in order to improve them and consequently enhance the global methane production yields.

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17

AD imposes several challenges in different aspects of the process; some of them, which are

The information used to develop the analysis was taken from official organisms such as:

• Ministry of Agriculture, Livestock, Rural Development, Fisheries and Food (SAGARPA)

Also, a workshop was organized in order to verify and complement the official information; the participants of the workshop were specialized people such as industrialists, farmers and

**a.** Feedstock. The production of agriculture wastes is computed from data provided by official organisms (usually until 2015). Three kinds of wastes are included since it is considered that its gathering is technically and economically feasible: i) rising and harvest wastes: products which are lost in the raising and harvest due to mechanical damages or products selection, ii) postharvest wastes: products that do not reach the market standards or that perish before the sell points and iii) foliage: biomass and all organic matter which

Four topics were considered in order to assess the biogas situation as follows:

specially related to transformation of agriculture wastes, are [3–6]:

• Ministry of Environment and Natural Resources (SEMARNAT)

• Agrifood and Fisheries Information Service (SIAP)

• National Institute of Statistics and Geography (INEGI).

stockbreeders from different regions of the country.

is leaved in soil in the harvest stage.

• Wastes composition

**2. Methods**

• Combination of substrates for co-digestion

• Reduction of inhibitory components.

• Ministry of Energy (SENER)

• Federal Electricity Board (CFE)

• National Water Board (CONAGUA)

• Development on solid-state anaerobic digestion

In this work, an analysis of the biogas from agricultural wastes is performed in order to identify the current status and opportunities for the next years in Mexico. Agriculture is an economic activity all around the country; besides products (fruits, vegetable, fodder), a large amount of wastes is generated in each stage of this activity: raising, harvesting and distribution. Only in the harvesting, it is estimated a production of 75 Mt of agricultural wastes. Many of them are traditionally used as fodder; some others are left in crop lands in order to promote the soil recovery and to improve the soil production. A few of them are studied as raw material to synthesize chemical products at industrial level. Then, only a small part of agricultural wastes is available as raw material for biogas production. However, it is necessary to assess the biomethane potentials in the national and international energy context.

#### **1.2. Anaerobic digestion for biogas production**

Anaerobic digestion (AD) is the process for wastes transformation into biogas. It is a natural mechanism of Earth to re-integrate organic wastes into the ecosystem dynamics. This process has been studied from many years ago, nowadays is well known and it is an active scientific topic [1–3]. AD is developed by many interdependent micro-organism communities, living in an environment free of oxygen, to transform complex substrates in four main stages: hydrolysis, acetogenesis, acidogenesis and methanogenesis; each stage has specific dynamics and three main phenomena are involved: physicochemical, hydrodynamic and biological. In optimal conditions, AD produces a biogas mainly composed of methane (50–80%) and carbon dioxide (48–18%); depending on the substrate, some other components (NO<sup>x</sup> , SO<sup>x</sup> ) are also present in low concentration (1–2%).

It has been determined that hydrolysis and methanogenesis are the limiting steps of AD. Hydrolysis is the stage where most complex substrates should be transformed, if there is an excess of complex molecules, the hydrolytic bacteria may become saturated and then inhibited; a consequence of this situation is the stopping of the complete AD process. On the other side, methanogenesis is the slowest stage and then the most important for the process stability; it is very sensitive to variations in the operating conditions such as: pH, temperature, overload on substrate concentration, etc. Then, these two stages receive special attention in order to improve them and consequently enhance the global methane production yields.

AD imposes several challenges in different aspects of the process; some of them, which are specially related to transformation of agriculture wastes, are [3–6]:

• Wastes composition

From some years ago, renewable sources are considered as a real alternative to deal with the society requirements. In 2010, the National Strategy for Energy (NSE) has been designed in order to state directives concerning the generation and management of the energy. An important objective of this strategy is to produce around 35% of energy from clean technologies in 2024. This goal implies challenges from scientific and technologic perspectives. Besides solar and wind energies, different initiatives have been implemented to promote biofuels, mainly, biodiesel, bioethanol and biogas. Agriculture and livestock wastes are being used as biogas source to produce energy in small and medium scale. Also, some industries use biogas to provide a part of the energy required in their processes. But, in general, the potential of biomethane production is not well seized yet. In the context of the ENS, biogas should be considered as an important topic due to the existence of several economical activities producing a lot of

In this work, an analysis of the biogas from agricultural wastes is performed in order to identify the current status and opportunities for the next years in Mexico. Agriculture is an economic activity all around the country; besides products (fruits, vegetable, fodder), a large amount of wastes is generated in each stage of this activity: raising, harvesting and distribution. Only in the harvesting, it is estimated a production of 75 Mt of agricultural wastes. Many of them are traditionally used as fodder; some others are left in crop lands in order to promote the soil recovery and to improve the soil production. A few of them are studied as raw material to synthesize chemical products at industrial level. Then, only a small part of agricultural wastes is available as raw material for biogas production. However, it is necessary to assess the biomethane potentials in the national and interna-

Anaerobic digestion (AD) is the process for wastes transformation into biogas. It is a natural mechanism of Earth to re-integrate organic wastes into the ecosystem dynamics. This process has been studied from many years ago, nowadays is well known and it is an active scientific topic [1–3]. AD is developed by many interdependent micro-organism communities, living in an environment free of oxygen, to transform complex substrates in four main stages: hydrolysis, acetogenesis, acidogenesis and methanogenesis; each stage has specific dynamics and three main phenomena are involved: physicochemical, hydrodynamic and biological. In optimal conditions, AD produces a biogas mainly composed of methane (50–80%) and carbon

It has been determined that hydrolysis and methanogenesis are the limiting steps of AD. Hydrolysis is the stage where most complex substrates should be transformed, if there is an excess of complex molecules, the hydrolytic bacteria may become saturated and then inhibited; a consequence of this situation is the stopping of the complete AD process. On the other side, methanogenesis is the slowest stage and then the most important for the process

, SO<sup>x</sup>

) are also

dioxide (48–18%); depending on the substrate, some other components (NO<sup>x</sup>

organic wastes.

16 Biofuels - State of Development

tional energy context.

**1.2. Anaerobic digestion for biogas production**

present in low concentration (1–2%).


#### **2. Methods**

The information used to develop the analysis was taken from official organisms such as:


Also, a workshop was organized in order to verify and complement the official information; the participants of the workshop were specialized people such as industrialists, farmers and stockbreeders from different regions of the country.

Four topics were considered in order to assess the biogas situation as follows:

**a.** Feedstock. The production of agriculture wastes is computed from data provided by official organisms (usually until 2015). Three kinds of wastes are included since it is considered that its gathering is technically and economically feasible: i) rising and harvest wastes: products which are lost in the raising and harvest due to mechanical damages or products selection, ii) postharvest wastes: products that do not reach the market standards or that perish before the sell points and iii) foliage: biomass and all organic matter which is leaved in soil in the harvest stage.

**b.** Potential for biogas production. The assessment of the energy potential is done considering the amount of wastes and the efficiency reported from experiments of biogas transformation in different regions of the country; when this efficiency is unknown a typical one (from specialized literature) is used.

and medicinal plants. Concerning the mass production, 290 Mt of ornamental plants were obtained in 2015, which correspond to the 40% of the total agriculture production in that year. The categories which are not considered as raw material for biomethane production are Aromatic herb, Grain and seed, Fodder and Other. The reason for this exception is since either the wastes production is negligible (the case of most of aromatic herbs) or the wastes are used for specific applications. For example, most of wastes from grains crops are used as fodder. Also, most of those wastes are hard to be transformed into biogas due to the low moisture

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19

Although it is possible to transform these kinds of wastes into biogas by anaerobic digestion, they are better situated for other type of processes, such as thermochemical ones (combustion,

As said before, although there is a large production of wastes, only a fraction of them could be available for biomethane production. In the case of aromatic herbs, almost all the plant is profitable; that means, the organic wastes production is negligible. Besides, most of wastes from grains and seeds crops are used as fodder either in small or large scale. Also, an amount of the produced wastes from crops of fruits, vegetables and even fodder are left in the soil in order to protect the surface and to keep the productivity. In addition, it is not possible to col-

Then, a selection of crops was done considering the generation of wastes, the feasibility to collect them and its suitability to be transformed into biogas. On the basis of these criteria, 36 species were considered as source of wastes for biomethane production. The selected species

*AW* = *AP* ∙ *WF* (1)

where *AW* is the agricultural wastes, *AP* is the agricultural production and *WF* is a waste factor which determines the amount of wastes produced from a specific crop. Then, the total

*AWT* = ∑*<sup>i</sup> APi* ∙ *WFi* (2)

The respective waste factors were deduced from information reported in different works [7–14]. Based on an analysis of the reported information, in this work a general formula to

*WF* = 0.5 ∙ *WH* + 0.5 ∙ *WPH* + 0.6 ∙ *WFB* (3)

where *<sup>W</sup> <sup>H</sup>* represents the wastes obtained in the harvesting stage, *<sup>W</sup> PH* the wastes generated in the post-harvest stage and *<sup>W</sup> FB* the wastes from plants foliage. It has been considered that 50% of the wastes from harvest and post-harvest stage are available for biogas production; the other 50%

An estimation of the wastes production from these crops is done by using Eq. (1).

pyrolysis and gasification), or fermentation with a previous treatment.

and high fiber content.

lect all the produced wastes.

waste production (*AWT*

are among fruits, vegetables and ornamental plants.

calculate the waste factors is proposed as follows:

) is obtained with:


#### **3. Results and discussion**

#### **3.1. Feedstock**

The available surface for agriculture in Mexico is around 27 Mha and it is distributed all around the country. Due to the weather and geographic conditions, a large diversity of plants is raised: fruits, vegetables, grains, ornamental plants, etc. According with the SIAP, there were 326 crops in 2015 with a global production of around 677.76 Mt.

A relative classification of these products is presented in **Figure 1**. The most abundant are fruits and ornamental plants: 69 different kinds of fruits are raised, corresponding to 22% of the agriculture products; a similar amount is obtained for ornamental plants. Besides, the categories vegetables and grain and seeds concentrate 32% of products, aromatic herbs and fodder correspond to 15%. The item Other includes products such as agave, Christmas tree

**Figure 1.** Relative classification of products from agriculture in Mexico.

and medicinal plants. Concerning the mass production, 290 Mt of ornamental plants were obtained in 2015, which correspond to the 40% of the total agriculture production in that year.

**b.** Potential for biogas production. The assessment of the energy potential is done considering the amount of wastes and the efficiency reported from experiments of biogas transformation in different regions of the country; when this efficiency is unknown a typical one

**c.** Technology for biogas utilization. The mechanisms currently used for biogas utilization

**d.** Perspectives. Alternatives and strategies to implement systematically the biogas technol-

The available surface for agriculture in Mexico is around 27 Mha and it is distributed all around the country. Due to the weather and geographic conditions, a large diversity of plants is raised: fruits, vegetables, grains, ornamental plants, etc. According with the SIAP, there

A relative classification of these products is presented in **Figure 1**. The most abundant are fruits and ornamental plants: 69 different kinds of fruits are raised, corresponding to 22% of the agriculture products; a similar amount is obtained for ornamental plants. Besides, the categories vegetables and grain and seeds concentrate 32% of products, aromatic herbs and fodder correspond to 15%. The item Other includes products such as agave, Christmas tree

were 326 crops in 2015 with a global production of around 677.76 Mt.

**Figure 1.** Relative classification of products from agriculture in Mexico.

(from specialized literature) is used.

were obtained directly from users.

ogy are presented.

18 Biofuels - State of Development

**3.1. Feedstock**

**3. Results and discussion**

The categories which are not considered as raw material for biomethane production are Aromatic herb, Grain and seed, Fodder and Other. The reason for this exception is since either the wastes production is negligible (the case of most of aromatic herbs) or the wastes are used for specific applications. For example, most of wastes from grains crops are used as fodder. Also, most of those wastes are hard to be transformed into biogas due to the low moisture and high fiber content.

Although it is possible to transform these kinds of wastes into biogas by anaerobic digestion, they are better situated for other type of processes, such as thermochemical ones (combustion, pyrolysis and gasification), or fermentation with a previous treatment.

As said before, although there is a large production of wastes, only a fraction of them could be available for biomethane production. In the case of aromatic herbs, almost all the plant is profitable; that means, the organic wastes production is negligible. Besides, most of wastes from grains and seeds crops are used as fodder either in small or large scale. Also, an amount of the produced wastes from crops of fruits, vegetables and even fodder are left in the soil in order to protect the surface and to keep the productivity. In addition, it is not possible to collect all the produced wastes.

Then, a selection of crops was done considering the generation of wastes, the feasibility to collect them and its suitability to be transformed into biogas. On the basis of these criteria, 36 species were considered as source of wastes for biomethane production. The selected species are among fruits, vegetables and ornamental plants.

An estimation of the wastes production from these crops is done by using Eq. (1).

$$A\mathbf{W} = AP \cdot \mathbf{W} \mathbf{F} \tag{1}$$

where *AW* is the agricultural wastes, *AP* is the agricultural production and *WF* is a waste factor which determines the amount of wastes produced from a specific crop. Then, the total waste production (*AWT* ) is obtained with:

$$\text{AW}\_{\text{T}} = \sum\_{l} \text{AP}\_{l} \cdot \text{WF}\_{l} \tag{2}$$

The respective waste factors were deduced from information reported in different works [7–14]. Based on an analysis of the reported information, in this work a general formula to calculate the waste factors is proposed as follows:

$$\text{WF} = 0.5 \cdot \text{W}\_{\text{H}} + 0.5 \cdot \text{W}\_{\text{PH}} + 0.6 \cdot \text{W}\_{\text{FB}} \tag{3}$$

where *<sup>W</sup> <sup>H</sup>* represents the wastes obtained in the harvesting stage, *<sup>W</sup> PH* the wastes generated in the post-harvest stage and *<sup>W</sup> FB* the wastes from plants foliage. It has been considered that 50% of the wastes from harvest and post-harvest stage are available for biogas production; the other 50% could be used as traditionally. Besides, foliage which could be collected and transformed into biogas is around 60% and the other 40% can be used as nowadays. The amount of foliage (*<sup>W</sup> FB*) is computed on the basis of the harvesting index, which relates the total biomass in a plant [14–16]. The wastes generated in the post-harvesting stage (*<sup>W</sup> PH*) are estimated according with [7]. Also, the next expression to estimate the wastes from harvesting stage is proposed:

$$W\_H = P \cdot \left(\frac{100}{100 - \text{WI}} - 1\right) \tag{4}$$

**Species Production Harvest Post-harvest Foliage Available** Apple 750324.85 187581.21 60025.99 123803.60 Apricot 1086.55 271.64 86.92 179.28 Asparagus 198075.04 49518.76 15846.00 222315.00 166071.38 Avocado 1644225.86 411056.47 131538.07 447229.43 Banana 2262028.25 565507.06 180962.26 615271.68 Broccoli 449185.37 112296.34 35934.83 1310124.00 908252.82 Dragon fruit 4542.28 1135.57 363.38 1235.50 Cabbage 226702.39 56675.60 18136.19 343680.00 267871.05 Cauliflower 68832.29 17208.07 5506.58 5490.43 22016.64 Carrot 318365.81 47571.90 41387.56 314500.00 264006.32 Chayote 163743.50 40935.88 13099.48 66525.00 84453.23 Courgette 456570.28 114142.57 36525.62 658025.00 519002.12 Cucumber 817799.83 204449.96 65423.99 658025.00 617256.55 Grapefruit 424315.36 106078.84 33945.23 115413.78 Green tomato 683984.96 170996.24 54718.80 1681234.00 1194784.31 Guava 294422.68 73605.67 23553.81 80082.97 Lettuce 437561.70 109390.43 35004.94 30356.80 137230.86 Mammee apple 18321.03 4580.26 1465.68 4983.32 Mandarin orange 291078.27 72769.57 23286.26 79173.29 Mango 1775506.77 443876.69 142040.54 482937.84 Melon 561891.31 140472.83 44951.30 457650.00 427424.44

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21

358799.76 71759.95 71759.95

408445.05 102111.26 32675.60 111097.05

Orange 4515520.33 1128880.08 361241.63 1228221.53 Papaya 883592.54 220898.14 70687.40 240337.17 Peach 176302.74 44075.69 14104.22 47954.35 Pear 24679.04 6169.76 1974.32 6712.70 Pineapple 840486.46 210121.62 67238.92 228612.32 Plum 72206.82 18051.71 5776.55 19640.26 Potato 1727345.51 258109.10 224554.92 1228180.00 1145494.70

Rambutan 8840.97 2210.24 707.28 2404.74 Sapota 17167.30 4291.83 1373.38 4669.51 Spinach 39738.91 9934.73 3179.11 10808.98

Ornamental plants

Prickly pear cactus

*WI* is the waste index, which is deduced from information reported in [7].

The information corresponding to the agricultural wastes produced from the selected species is presented in **Table 1**.

The Production column contains the reported production on the official records of SIAP. The Harvest, Post-harvest and Foliage columns include the estimation of wastes on the corresponding stage. The last column presents the estimation of wastes available for biogas production. A total of 12.7 Mt of wastes from the considered crops was estimated. This amount could provide either fuel or electricity to cover a fraction of the energy demand in the agriculture activities, as shown below.

#### **3.2. Potential for biogas production**

There exist different works related to biogas production from agriculture wastes [17–24], the yield depends on specific operating conditions and raw materials. In order to ease the data processing, in this study, the estimation of the biogas production from the selected agriculture wastes is done by following an experimental method developed for energy production from wastes in an herbalist facility [25]. This is based on the total solids, the biodegradable solids on the raw material (the fraction of biomass which can be transformed into biogas by anaerobic bacteria) and a conversion efficiency factor. Then, the estimation of biogas is done with the next equation:

$$V\_{bigus} = \gamma \cdot V \text{BS} \tag{5}$$

where *Vbiogas* is the estimated biogas production, *VBS* the biodegradable volatile solids in the raw material and *γ* the conversion efficiency factor. *VBS* are computed as follows:

$$\text{VBS} = \mathbf{a\_i} \cdot \mathbf{a\_i} \cdot \text{TS} \tag{6}$$

where *TS* is the total solids and *α*<sup>1</sup> and *α*<sup>2</sup> are coefficients related to the fraction of volatile solids in total solids and the fraction of biodegradable solids in volatile solids, respectively.

On the other side, the estimation of the energy content on the produced biogas is done considering a concentration of 50% of methane. This value is easily reached in anaerobic digestion processes. The equation to obtain the potential of energy generation (*Ebiogas*) is:

$$\mathbf{E}\_{\text{bigas}} = \mathbf{C} \mathbf{H}\_4 \cdot \mathbf{H} \mathbf{V}\_{\text{methane}} \cdot \mathbf{V}\_{\text{bigas}} \tag{7}$$

The Potential for Biogas Production from Agriculture Wastes in Mexico http://dx.doi.org/10.5772/intechopen.75457 21


could be used as traditionally. Besides, foliage which could be collected and transformed into biogas is around 60% and the other 40% can be used as nowadays. The amount of foliage (*<sup>W</sup> FB*) is computed on the basis of the harvesting index, which relates the total biomass in a plant [14–16]. The wastes generated in the post-harvesting stage (*<sup>W</sup> PH*) are estimated according with

\_\_\_\_\_\_ 100

The information corresponding to the agricultural wastes produced from the selected species

The Production column contains the reported production on the official records of SIAP. The Harvest, Post-harvest and Foliage columns include the estimation of wastes on the corresponding stage. The last column presents the estimation of wastes available for biogas production. A total of 12.7 Mt of wastes from the considered crops was estimated. This amount could provide either fuel or electricity to cover a fraction of the energy demand in the agricul-

There exist different works related to biogas production from agriculture wastes [17–24], the yield depends on specific operating conditions and raw materials. In order to ease the data processing, in this study, the estimation of the biogas production from the selected agriculture wastes is done by following an experimental method developed for energy production from wastes in an herbalist facility [25]. This is based on the total solids, the biodegradable solids on the raw material (the fraction of biomass which can be transformed into biogas by anaerobic bacteria) and a conversion efficiency factor. Then, the estimation of biogas is done with the next equation:

*Vbiogas* = *γ* ∙ *VBS* (5)

where *Vbiogas* is the estimated biogas production, *VBS* the biodegradable volatile solids in the raw

*VBS* = *α*<sup>1</sup> ∙ *α*<sup>2</sup> ∙ *TS* (6)

On the other side, the estimation of the energy content on the produced biogas is done considering a concentration of 50% of methane. This value is easily reached in anaerobic digestion

E*biogas* = *CH*<sup>4</sup> ∙ *HVmethane* ∙ *Vbiogas* (7)

in total solids and the fraction of biodegradable solids in volatile solids, respectively.

are coefficients related to the fraction of volatile solids

material and *γ* the conversion efficiency factor. *VBS* are computed as follows:

and *α*<sup>2</sup>

processes. The equation to obtain the potential of energy generation (*Ebiogas*) is:

<sup>100</sup> <sup>−</sup> *WI* − 1) (4)

[7]. Also, the next expression to estimate the wastes from harvesting stage is proposed:

*WI* is the waste index, which is deduced from information reported in [7].

*WH* = *P* ∙ (

is presented in **Table 1**.

20 Biofuels - State of Development

ture activities, as shown below.

where *TS* is the total solids and *α*<sup>1</sup>

**3.2. Potential for biogas production**


**Species Wastes (t) Biogas (m3**

Apple 123803.60 48283404.10 979911686.16 Apricot 179.28 69919.49 1419016.10 Asparagus 166071.38 64767838.82 1314463288.93 Avocado 447229.43 174419479.23 3539843330.95 Banana 615271.68 239955956.76 4869906142.44 Broccoli 908252.82 354218599.07 7188866468.22 Dragon fruit 1235.50 481845.06 9779045.54 Cabbage 267871.05 104469709.53 2120212754.94 Cauliflower 22016.64 8586490.41 174262822.90 Carrot 264006.32 102962465.54 2089623238.04 Chayote 84453.23 32936760.48 668451553.94 Courgette 519002.12 202410825.30 4107927699.51 Cucumber 617256.55 240730055.97 4885616485.84 Grapefruit 115413.78 45011373.39 913505822.93 Green tomato 1194784.31 465965880.56 9456777545.90 Guava 80082.97 31232357.89 633860703.47 Lettuce 137230.86 53520036.34 1086189137.44 Mammee apple 4983.32 1943494.86 39443228.23 Mandarin orange 79173.29 30877582.88 626660544.58 Mango 482937.84 188345758.16 3822477161.89 Melon 427424.44 166695530.16 3383085784.69 Ornamental plants 71759.952 27986381.28 567983608.08 Orange 1228221.53 479006396.61 9721434819.13 Papaya 240337.17 93731496.64 1902280724.37 Peach 47954.35 18702194.66 379561040.61 Pear 6712.70 2617952.56 53131347.27 Pineapple 228612.32 89158803.68 1809477920.62 Plum 19640.26 7659699.47 155453600.65 Potato 1145494.70 446742934.57 9066647857.10 Prickly pear cactus 111097.05 43327850.90 879338734.10 Rambutan 2404.74 937850.10 19033667.73 Sapota 4669.51 1821107.18 36959370.30 Spinach 10808.98 4215503.57 85553645.01 Soursop 4520.89 1763146.13 35783050.77

**) Energy (MJ)**

The Potential for Biogas Production from Agriculture Wastes in Mexico

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23

**Table 1.** Production of wastes from agriculture (t).

where CH<sup>4</sup> is the methane concentration in biogas and *HVmethane* is the heat value of pure methane, which is 8840 kcal (36.9 MJ). The results of this estimation are presented in **Table 2**.

The biogas which could be produced from these agricultural wastes is estimated on 4953 × 109 m3 and the energy content is around 100 GJ. The production of electricity considering typical efficiency of internal combustion engines and electric generators is around 8300 GWh. This amount of energy is a little value in comparison of the total primary consumption in the country, which is near to 11,000 PJ per year. However, a systematic transformation of biomass for biogas production could be an interesting alternative not only for the energy generation but also for the environmental sector since it represents a mechanism for wastes management.

At present time, different biogas processes have been identified at different production scales. Some examples of them are shown in **Table 3**.

#### **3.3. Technology**

Biogas is a versatile fuel which can be transformed into energy by following different pathways [26, 27]. **Figure 2** includes a schematic representation of the biogas applications in the context of agriculture wastes transformation.

Thermal and electrical energy are the main alternatives to take advantage of biogas. The former can be employed for heating services either in farms or in residential applications; also, it can be used as energy source for food cooking and even for lighting through lamps fueled by biogas. The last one can be used to provide energy for household applications. In a larger scale, it is feasible to inject it to the national energy grid in order to be managed by the National Energy Board in Mexico (CFE); this is nowadays possible thanks to the recent modifications to the energy management laws. In next paragraphs, technologies currently used, and some alternatives, to profit the biogas potentials in Mexico are briefly described.

#### *3.3.1. Thermal energy*

Thermal energy is obtained from a biogas combustion process; the technology depends on the final applications. Among the alternatives, it is possible to find burners, stoves and lamps.


where CH<sup>4</sup>

22 Biofuels - State of Development

**3.3. Technology**

*3.3.1. Thermal energy*

Some examples of them are shown in **Table 3**.

**Table 1.** Production of wastes from agriculture (t).

context of agriculture wastes transformation.

109 m3

is the methane concentration in biogas and *HVmethane* is the heat value of pure meth-

ane, which is 8840 kcal (36.9 MJ). The results of this estimation are presented in **Table 2**.

**Species Production Harvest Post-harvest Foliage Available** Soursop 16620.91 4155.23 1329.67 4520.89 Strawberry 392625.19 98156.30 31410.02 99650.00 166584.05 Tangerine 195111.08 48777.77 15608.89 53070.21 Tomato 3098329.41 774582.35 247866.35 1936556.00 2004679.20 Watermelon 1020268.73 255067.18 81621.50 863525.00 795628.09 **Total 25644645.13 6115714.51 2125153.20 9947596.18 12700876.13**

The biogas which could be produced from these agricultural wastes is estimated on 4953 ×

Biogas is a versatile fuel which can be transformed into energy by following different pathways [26, 27]. **Figure 2** includes a schematic representation of the biogas applications in the

Thermal and electrical energy are the main alternatives to take advantage of biogas. The former can be employed for heating services either in farms or in residential applications; also, it can be used as energy source for food cooking and even for lighting through lamps fueled by biogas. The last one can be used to provide energy for household applications. In a larger scale, it is feasible to inject it to the national energy grid in order to be managed by the National Energy Board in Mexico (CFE); this is nowadays possible thanks to the recent modifications to the energy management laws. In next paragraphs, technologies currently used, and some alternatives, to profit the biogas potentials in Mexico are briefly described.

Thermal energy is obtained from a biogas combustion process; the technology depends on the final applications. Among the alternatives, it is possible to find burners, stoves and lamps.

 and the energy content is around 100 GJ. The production of electricity considering typical efficiency of internal combustion engines and electric generators is around 8300 GWh. This amount of energy is a little value in comparison of the total primary consumption in the country, which is near to 11,000 PJ per year. However, a systematic transformation of biomass for biogas production could be an interesting alternative not only for the energy generation but also for the environmental sector since it represents a mechanism for wastes management. At present time, different biogas processes have been identified at different production scales.

#### 24 Biofuels - State of Development


**Table 2.** Estimation of the biogas production from agricultural wastes.


On the other side, the adaptation of natural gas stoves to biogas is not complex [27]. Two alternatives are identified in order to allow the biogas to produce a similar flame as the one from natural gas: adaptation or replacement of burners. First one requires to increase the diffuser vent diameter and to regulate (decrease) the air in the mix biogas/air to reach a good flame quality. Replacement of burner implies also a replacement of the biogas pipeline; either stainless steel or PVC pipes are better situated for biogas flows since they are more tolerant to corrosive elements on biogas. As for the previous case, it is necessary to regulate the relation biogas/air.

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Lighting is produced by biogas lamps. Its efficiency is low (30–50%); however, this is a good alternative to facilities outside the national electrical grid coverage, and also for some specific situations in farms. Light is produced from the luminosity properties of materials such as lanthanum, cerium and thorium when they are exposed to high temperature (provided in this case from the biogas combustion). With these materials, it is possible to obtain light in the range of 400 and 500 lm, which is similar to 25–75 W. There are some commercial alternatives of biogas lamps, such as Puxin, Xunda, Taiyangyan, Rupak and Huamei. Coleman offers a

Electricity from biogas can be obtained by two alternatives: electromechanical systems and electrochemical devices. Electromechanical systems require the combustion of fuels to produce mechanical energy which is transformed in electricity by the electromagnetic induction

variety of gas lamps, which could be adapted for biogas.

*3.3.2. Lighting*

**Figure 2.** Biogas to energy alternatives.

*3.3.3. Electrical energy*

**Table 3.** Processes for biogas production from agriculture wastes identified in Mexico.

#### *3.3.1.1. Burners*

There exist commercial biogas burners which provide heat in conditioning thermal systems. For example, EcoFlam and Sayercen. EcoFlam is an Italian enterprise offering medium- and largescale burners employing gaseous fuels including biogas. The thermal power is ranged from 7 kW to 25 MW. They can be easily adapted for households and industrial applications such as boilers, calefaction and drying systems, furnaces, greenhouses and heat regeneration systems, among others. Besides, Sayercen is a Mexican enterprise focused on the management of organic wastes in farms for production and utilization of biogas. They have integrated different technologies to produce, heat, steam and flames which are employed in farms and slaughterhouses.

In addition, biogas could be used by devices designed for natural gas applications; in this case, the injection conditions should be modified. Due to the different composition and lower calorific value of biogas, a larger input flow is required; also, the air content should be more than 20% and the pressure should be among 7 and 20 mbar.

#### *3.3.1.2. Stoves*

Biogas stoves are an interesting alternative for small facilities, e.g. rural towns and small farms. There are not national commercial devices, but there exist different Chinese organizations, such as Puxin, Xunda, Huamei and Taiyangyan, offering biogas stoves.

The Potential for Biogas Production from Agriculture Wastes in Mexico http://dx.doi.org/10.5772/intechopen.75457 25

**Figure 2.** Biogas to energy alternatives.

On the other side, the adaptation of natural gas stoves to biogas is not complex [27]. Two alternatives are identified in order to allow the biogas to produce a similar flame as the one from natural gas: adaptation or replacement of burners. First one requires to increase the diffuser vent diameter and to regulate (decrease) the air in the mix biogas/air to reach a good flame quality. Replacement of burner implies also a replacement of the biogas pipeline; either stainless steel or PVC pipes are better situated for biogas flows since they are more tolerant to corrosive elements on biogas. As for the previous case, it is necessary to regulate the relation biogas/air.

#### *3.3.2. Lighting*

*3.3.1.1. Burners*

*3.3.1.2. Stoves*

There exist commercial biogas burners which provide heat in conditioning thermal systems. For example, EcoFlam and Sayercen. EcoFlam is an Italian enterprise offering medium- and largescale burners employing gaseous fuels including biogas. The thermal power is ranged from 7 kW to 25 MW. They can be easily adapted for households and industrial applications such as boilers, calefaction and drying systems, furnaces, greenhouses and heat regeneration systems, among others. Besides, Sayercen is a Mexican enterprise focused on the management of organic wastes in farms for production and utilization of biogas. They have integrated different technologies to produce, heat, steam and flames which are employed in farms and slaughterhouses. In addition, biogas could be used by devices designed for natural gas applications; in this case, the injection conditions should be modified. Due to the different composition and lower calorific value of biogas, a larger input flow is required; also, the air content should be more

 **m3**

**) Energy (MJ)**

**) Potential electricity kWh m−3**

Biogas stoves are an interesting alternative for small facilities, e.g. rural towns and small farms. There are not national commercial devices, but there exist different Chinese organiza-

tions, such as Puxin, Xunda, Huamei and Taiyangyan, offering biogas stoves.

than 20% and the pressure should be among 7 and 20 mbar.

**Raw material Escala Potential biogas (m3**

**Table 2.** Estimation of the biogas production from agricultural wastes.

**Species Wastes (t) Biogas (m3**

24 Biofuels - State of Development

Mango wastes Laboratory 3.14 7.74 Residuos de cultivo de jitomate Laboratory 0.911 2.24 Residuos de papaya Semi-pilot 1.59 3.92 Residuos de plátano Semi-pilot 4.6 11.35 Residuos de brócoli Pilot 40 100 Nopales Commercial 68.75 197 Algas Laboratory 85.5 85.7

Strawberry 166584.05 64967780.16 1318521098.25 Tangerine 53070.21 20697383.37 420053395.42 Tomato 2004679.20 781824887.81 15867136098.16 Watermelon 795628.09 310294956.88 6297436149.85 **Total 12700876.13 4953341689.58 100528069590.05**

**Table 3.** Processes for biogas production from agriculture wastes identified in Mexico.

Lighting is produced by biogas lamps. Its efficiency is low (30–50%); however, this is a good alternative to facilities outside the national electrical grid coverage, and also for some specific situations in farms. Light is produced from the luminosity properties of materials such as lanthanum, cerium and thorium when they are exposed to high temperature (provided in this case from the biogas combustion). With these materials, it is possible to obtain light in the range of 400 and 500 lm, which is similar to 25–75 W. There are some commercial alternatives of biogas lamps, such as Puxin, Xunda, Taiyangyan, Rupak and Huamei. Coleman offers a variety of gas lamps, which could be adapted for biogas.

#### *3.3.3. Electrical energy*

Electricity from biogas can be obtained by two alternatives: electromechanical systems and electrochemical devices. Electromechanical systems require the combustion of fuels to produce mechanical energy which is transformed in electricity by the electromagnetic induction

• Caterpillar. The electric power plants offered by Caterpillar are fuel-flexible; then, they can operate with biogas. The main detected applications are in power generation with biogas from landfills, wastewater treatment plants and animal wastes; however, they could operate with any biogas containing the adequate methane concentration. The power generation

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**Table 4** includes a relationship of the equipment implemented in Mexico for electricity gen-

From this information, it can be deduced that the commercial power electric plants are available for more than 30 kW. This implies an approximate consumption of biogas of 12 m<sup>3</sup> h−1. For applications less than 30 kW (a fewer capacity to produce biogas), other alternatives should be explored. For example: a) the adaptation of small either diesel or oil engines to allow them to operate with biogas; after that, it is advisable to connect them to small electric generators. Even if the conversion efficiency decreases, it is a feasible option to produce electricity from biogas at small scale; b) the use of biogas only to produce thermal energy; for low biogas production, the thermal energy is the best option since only a combustion process is required and there are not large lost of the potential energy and c) the methane up-grade in biogas, this allow to get a better quality fuel since the calorific value increases; a direct benefit of this situation is the reach large efficiencies at low scale. Nevertheless, this alternative requires more research at technological transfer: in fact, it is necessary to develop efficient devices to

External combustion engines can be used for energy production with biogas [29]. The Stirling cycle is based on the work produced form the expansion and contraction of a gas from a cold point to a hot one. The temperature on the hot point can be provided by the combustion of

**Equipment Number of implemented engines Installed capacity**

Mopesa 11 720 kW Jidoka 16 1095 kW Cummins 1 100 kW Jenbacher 13 13.68 MW Guascor 3 2.85 MW Caterpillar 5 4.3 MW Confidencial 3 1.28 MW Other 107 6.42 MW

**Table 4.** Biogas engines coupled to electric generators implemented in Mexico.

is ranged from 64 to 3770 kW.

up-grade biomethane in biogas.

biogas, which takes place outside the engine.

*3.3.3.2. Stirling engines*

eration from biogas.

**Figure 3.** Electricity production from electromechanical devices.

principle (**Figure 3**). The alternatives for biogas transformation into mechanical are internal combustion engines, Stirling engines and turbines. In Mexico, internal combustion engines are preferred for electricity generation in comparison with the other two options.

#### *3.3.3.1. Internal combustion engines*

These engines have been studied from many years ago. They operate under the ignition by compression (Diesel cycle) or spark (Otto cycle).

The oil and diesel engines are modifiable to operate with biogas [28]. The injection system should be adapted to allow a larger gas flow and reach the adequate relation in the mixture fuel/air. In addition, it is necessary to synchronize the injection with the compression stage. Another alternative is to purify biogas in order to separate the CO2 and to allow the methane to be the only component in the mix fuel/air for the thermodynamic cycle.

There are several commercial biogas engines for electricity generation. In Mexico, the most used are Mopesa, Cummins (adapted), Guascor and Jenbacher:


• Caterpillar. The electric power plants offered by Caterpillar are fuel-flexible; then, they can operate with biogas. The main detected applications are in power generation with biogas from landfills, wastewater treatment plants and animal wastes; however, they could operate with any biogas containing the adequate methane concentration. The power generation is ranged from 64 to 3770 kW.

**Table 4** includes a relationship of the equipment implemented in Mexico for electricity generation from biogas.

From this information, it can be deduced that the commercial power electric plants are available for more than 30 kW. This implies an approximate consumption of biogas of 12 m<sup>3</sup> h−1. For applications less than 30 kW (a fewer capacity to produce biogas), other alternatives should be explored. For example: a) the adaptation of small either diesel or oil engines to allow them to operate with biogas; after that, it is advisable to connect them to small electric generators. Even if the conversion efficiency decreases, it is a feasible option to produce electricity from biogas at small scale; b) the use of biogas only to produce thermal energy; for low biogas production, the thermal energy is the best option since only a combustion process is required and there are not large lost of the potential energy and c) the methane up-grade in biogas, this allow to get a better quality fuel since the calorific value increases; a direct benefit of this situation is the reach large efficiencies at low scale. Nevertheless, this alternative requires more research at technological transfer: in fact, it is necessary to develop efficient devices to up-grade biomethane in biogas.

#### *3.3.3.2. Stirling engines*

principle (**Figure 3**). The alternatives for biogas transformation into mechanical are internal combustion engines, Stirling engines and turbines. In Mexico, internal combustion engines

These engines have been studied from many years ago. They operate under the ignition by

The oil and diesel engines are modifiable to operate with biogas [28]. The injection system should be adapted to allow a larger gas flow and reach the adequate relation in the mixture fuel/air. In addition, it is necessary to synchronize the injection with the compression stage.

There are several commercial biogas engines for electricity generation. In Mexico, the most

• Mopesa offers power plants of 30 and 60 kW, 220 V and 60 Hz known as Econogas Power Plants; the first system includes a 4.07 L 4 cyl biogas engine coupled to a synchronous generator of 30 kW; the second one uses a 5.8 L 6 cyl biogas engine with a 60 kW synchronous generator. • Cummins. Diesel engines have been adapted to operate with biogas and they are connected to Marathon electric generators; the power is ranged among 40 and 100 kW and they are designed to be connected to the federal grid. The required biogas should content at least

• Guascor. These engines have been designed specifically to operate with biogas. The power capacity is ranged from 150 to 1240 kW. The biogas Guascor engines have been imple-

• GE-Jenbacher. Even if these engines are designed to operate with biogas from landfills and wastewater treatment plants, they are an alternative for biogas from other kind of wastes. The production power is ranged from 250 kW to 3 MW; that means, the engines are ideal for large scale applications. This technology could be employed either in single generation

and to allow the methane

are preferred for electricity generation in comparison with the other two options.

*3.3.3.1. Internal combustion engines*

26 Biofuels - State of Development

compression (Diesel cycle) or spark (Otto cycle).

**Figure 3.** Electricity production from electromechanical devices.

Another alternative is to purify biogas in order to separate the CO2

used are Mopesa, Cummins (adapted), Guascor and Jenbacher:

55% of methane in order to reach the claimed efficiency.

mented in cogeneration or single generation configurations.

or in cogeneration operation modes.

to be the only component in the mix fuel/air for the thermodynamic cycle.

External combustion engines can be used for energy production with biogas [29]. The Stirling cycle is based on the work produced form the expansion and contraction of a gas from a cold point to a hot one. The temperature on the hot point can be provided by the combustion of biogas, which takes place outside the engine.


**Table 4.** Biogas engines coupled to electric generators implemented in Mexico.

Only one Stirling engine operating with biogas to energy production has been identified in Mexico. This use the biogas obtained from animal wastes. These kinds of engines are easy to design and to operate. Then, they present clear opportunities from scientific and technologic developments.

**3.4. Perspectives**

development. This is schematized in **Figure 5**.

**Figure 5.** Strategy for transformation of agriculture wastes and energy crops products.

*3.4.1. Biorefinery approaches*

The potential of biomass for energy production in Mexico is large; besides agriculture, there are many other activities producing organic wastes. Since a single biogas production scheme may require high investment and operational costs some other complementary approaches should be explored. In this context, a national strategy should be implemented in order to achieve an optimal use of organic wastes, not only for energy production but for added value product generation. Based on the experience of some other countries all around the world, among the main topics which should be systematically addressed in Mexico the next could be considered: biorefinery approaches, biomethane upgrading, energy crops and technology

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The schemes for integral revalorization of biomass, known as biorefineries, are considered as a promising alterative to develop a global industry based on biomass [32]. These schemes combine different biomass conversion processes in order to produce biofuels and chemical products in an analogue structure of oil refineries. Anaerobic digestion has been identified as a biological pre-treatment that ease the subsequent transformation of the diverse components of biomass. Then, biogas can be only one of the multiple products which can be synthesized. Some other biofuels such as ethanol, hydrogen and butanol could be obtained. Besides, chemical products or precursors such as organic acids, biopolymers and biofertilizers are possible to be produced [33]. At current time, there are several reports concerning the development of biorefineries in Mexico [34]. Most of them are in the conceptualization stage; there are different efforts related to experimental studies in order to identify the best operating conditions. Some of them are

#### *3.3.3.3. Microturbines*

Turbines are well-known technology to produce energy at large scale. The fundamentals of them are based on the transformation of the kinetic energy of a fluid (water, steam, gas) into a mechanical energy. Nowadays, there are commercial developments which can operate at medium scale. Biogas is a feasible fuel for this kind of technology [30].

There are different commercial microturbines, such as Capstone and Siemens, which can be considered as an alternative to take advantage of biogas for a power production (more than 30 kW).

In Mexico, a beer company obtains biogas from the produced wastes in the beer production processes; the biogas is used to produce 6% of its energy consumption. The transformation is done by using biogas and steam in a cogeneration system.

#### *3.3.3.4. Fuel cells*

Fuel cells are electrochemical devices, which allow the energy of a chemical reaction to be transformed directly into electricity; they operate while being supplied with fuel and oxygen, then they do not neither become ended nor require to be recharged like conventional batteries. A basic operation principle of fuel cells is shown in **Figure 4**.

Research on this type of devices has made remarkable progress in recent years. Specifically, solid oxide (SOFC) cells have received special attention because they offer very high efficiency with relatively low sensitivity to the chemical composition of the fuel. The high operating temperature (700–1000°C) allows flexibility in relation to the fuel to be used. This implies that it is possible to use biogas, which cannot be used in other types of cells. SOFCs can be used in small power applications, stand-alone systems and remote systems [31]. Different research teams in Mexico deal with fuel cells.

**Figure 4.** Electricity generation principle from electrochemical devices.

#### **3.4. Perspectives**

Only one Stirling engine operating with biogas to energy production has been identified in Mexico. This use the biogas obtained from animal wastes. These kinds of engines are easy to design and to operate. Then, they present clear opportunities from scientific and technologic

Turbines are well-known technology to produce energy at large scale. The fundamentals of them are based on the transformation of the kinetic energy of a fluid (water, steam, gas) into a mechanical energy. Nowadays, there are commercial developments which can operate at

There are different commercial microturbines, such as Capstone and Siemens, which can be considered as an alternative to take advantage of biogas for a power production (more than 30 kW). In Mexico, a beer company obtains biogas from the produced wastes in the beer production processes; the biogas is used to produce 6% of its energy consumption. The transformation is

Fuel cells are electrochemical devices, which allow the energy of a chemical reaction to be transformed directly into electricity; they operate while being supplied with fuel and oxygen, then they do not neither become ended nor require to be recharged like conventional batter-

Research on this type of devices has made remarkable progress in recent years. Specifically, solid oxide (SOFC) cells have received special attention because they offer very high efficiency with relatively low sensitivity to the chemical composition of the fuel. The high operating temperature (700–1000°C) allows flexibility in relation to the fuel to be used. This implies that it is possible to use biogas, which cannot be used in other types of cells. SOFCs can be used in small power applications, stand-alone systems and remote systems [31]. Different research

medium scale. Biogas is a feasible fuel for this kind of technology [30].

done by using biogas and steam in a cogeneration system.

ies. A basic operation principle of fuel cells is shown in **Figure 4**.

**Figure 4.** Electricity generation principle from electrochemical devices.

developments.

*3.3.3.4. Fuel cells*

teams in Mexico deal with fuel cells.

*3.3.3.3. Microturbines*

28 Biofuels - State of Development

The potential of biomass for energy production in Mexico is large; besides agriculture, there are many other activities producing organic wastes. Since a single biogas production scheme may require high investment and operational costs some other complementary approaches should be explored. In this context, a national strategy should be implemented in order to achieve an optimal use of organic wastes, not only for energy production but for added value product generation. Based on the experience of some other countries all around the world, among the main topics which should be systematically addressed in Mexico the next could be considered: biorefinery approaches, biomethane upgrading, energy crops and technology development. This is schematized in **Figure 5**.

#### *3.4.1. Biorefinery approaches*

The schemes for integral revalorization of biomass, known as biorefineries, are considered as a promising alterative to develop a global industry based on biomass [32]. These schemes combine different biomass conversion processes in order to produce biofuels and chemical products in an analogue structure of oil refineries. Anaerobic digestion has been identified as a biological pre-treatment that ease the subsequent transformation of the diverse components of biomass. Then, biogas can be only one of the multiple products which can be synthesized. Some other biofuels such as ethanol, hydrogen and butanol could be obtained. Besides, chemical products or precursors such as organic acids, biopolymers and biofertilizers are possible to be produced [33].

At current time, there are several reports concerning the development of biorefineries in Mexico [34]. Most of them are in the conceptualization stage; there are different efforts related to experimental studies in order to identify the best operating conditions. Some of them are

**Figure 5.** Strategy for transformation of agriculture wastes and energy crops products.

briefly described. The Nerixis project has been developed by an interdisciplinary work team, and the objective was to develop the concept of a based agriculture wastes biorefinery; the structure included pre-treatment, saccharification, fermentation, separation, biogas, hydrogen and electricity co-production, enzyme enhancement, synthesis of lignine-based products, plant design and life cycle assessment (LCA); the considered raw material was wheat including streams of wastewater [35]. Additional schemes have been implemented from this project [36]. Other work explores the wastes of algae from a biodiesel productions process as raw material for ethylene and bioplastic production [37]. Mango wastes have been employed as raw material for bioethanol and food supplement production in a biorefinery scheme [38]. Other research deals with the evaluation of biohydrogen production from agro-industrial wastewaters and by-products; six different wastewaters and industrial by-products coming from cheese, fruit juice, paper, sugar, fruit processing and spirits factories were evaluated [39].

• Absorption with organic solvents.

Concerning biogas cleaning, the issues are related with the elimination of corrosive compounds, which affect the equipment used in the energy generation stage. Among the harmful agents, most commonly found in biogas are sulfur and nitrogen compounds. Methods to remove these chemical compounds are studied. The compound that receives most attention

The Potential for Biogas Production from Agriculture Wastes in Mexico

http://dx.doi.org/10.5772/intechopen.75457

31

S due to its impact on the mechanical parts of the devices as well as on the environment:

Biogas cleaning and upgrading is few addressed in Mexico; however, it is an important issue which could diversify the use of biogas and even to promote the transformation of agriculture

Although there is some equipment designed for national entrepreneurs, most of the commercial technology associated to the biogas life cycle is foreign. At present time, commercial globalization and the international free trade agreements allow to get low prices for several products. However, since the biogas topic is not really spread at small and medium size, the

Then, the development of technology is a topic which should be addressed in Mexico, especially for small applications such as burners, furnaces, stoves, lamps, small engines for

Due to the geographic characteristic of the country, the production of agriculture wastes is not uniformly distributed. This implies an additional issue on the collection stage for large size biogas facilities. Then, it is advisable to consider a distributed generation approach; that means, to implement small-scale facilities transforming small quantities of biomass and producing small quantities of energy, but near to the final users. This allows a better management of resources. Then, the distributed structures are designed to avoid logistic problems for transportation which demand energy, time and other resources. For this reason, the availability of

Energy crops should be also a developing topic for biogas production, preferentially in

importation of technology increases the initial investment for projects.

mechanical energy, and power plants for a generation less than 30 kW.

technology for medium and small size is an important aspect to be considered.

• Membrane technology.

• Biological desulfurization.

waste into biogas.

*3.4.4. Energy crops*

biorefinery schemes.

*3.4.3. Technology development*

• Chemical precipitation with ferrous compounds.

• Combination of adsorption and catalytic oxidation.

• Chemical reaction using iron compounds.

is H<sup>2</sup>

Besides the technical feasibility analysis, the economic, environmental and social aspects of biorefineries should be assessed. This is a topic considered in different Mexican studies. A multi-feed biorefinery (MPB10) for producing bioethanol from lignocellulosic residues and simultaneously treating agro-industrial wastes (cheese whey and tequila vinasses) was proposed. It was concluded that the most important sustainability indicators were the End-use Energy Ratio for the environmental aspect and Yield together with total production cost (TPC) per energy unit produced for the economic domain [35]. Other work is related to the sustainability assessment of a switchgrass-based biorefinery. Among the main results, it can be mentioned that some indicators such as the employment extent and raw materials consumption need to be improved in order to avoid risks; increasing operational jobs within the plant, increasing crop productivity or increasing the cropland surface may lead to better results on these indicators. Indicators concerning social domain are difficult to set on a sustainability scale, because commonly there is no possible definition for the ideal sustainability and/or the critical value [40].

Even if more research is required to consolidate the biorefineries topic, the next step in Mexico is the knowledge transfer for scaling up of processes. This is not an easy task since many factors should be in synchronization: government, farmers and academic sector.

#### *3.4.2. Biogas purification*

As said previously, biogas composition depends on the raw materials. The presence of compounds other than methane reduces the calorific value. The elimination of those compounds is a research topic with scientific and technologic interest. There are two main approaches relating biogas purification: biomethane upgrading and biogas cleaning [41].

The increase in the methane grade, known also as upgrading or enrichment, refers to the separation of the methane from the biogas in order to have a compound with higher energy potential. The idea is to recover methane in order to conserve the material representing the highest calorific value in biogas. There are different methods for this effect:


briefly described. The Nerixis project has been developed by an interdisciplinary work team, and the objective was to develop the concept of a based agriculture wastes biorefinery; the structure included pre-treatment, saccharification, fermentation, separation, biogas, hydrogen and electricity co-production, enzyme enhancement, synthesis of lignine-based products, plant design and life cycle assessment (LCA); the considered raw material was wheat including streams of wastewater [35]. Additional schemes have been implemented from this project [36]. Other work explores the wastes of algae from a biodiesel productions process as raw material for ethylene and bioplastic production [37]. Mango wastes have been employed as raw material for bioethanol and food supplement production in a biorefinery scheme [38]. Other research deals with the evaluation of biohydrogen production from agro-industrial wastewaters and by-products; six different wastewaters and industrial by-products coming from cheese, fruit juice, paper, sugar, fruit processing and spirits factories were evaluated [39]. Besides the technical feasibility analysis, the economic, environmental and social aspects of biorefineries should be assessed. This is a topic considered in different Mexican studies. A multi-feed biorefinery (MPB10) for producing bioethanol from lignocellulosic residues and simultaneously treating agro-industrial wastes (cheese whey and tequila vinasses) was proposed. It was concluded that the most important sustainability indicators were the End-use Energy Ratio for the environmental aspect and Yield together with total production cost (TPC) per energy unit produced for the economic domain [35]. Other work is related to the sustainability assessment of a switchgrass-based biorefinery. Among the main results, it can be mentioned that some indicators such as the employment extent and raw materials consumption need to be improved in order to avoid risks; increasing operational jobs within the plant, increasing crop productivity or increasing the cropland surface may lead to better results on these indicators. Indicators concerning social domain are difficult to set on a sustainability scale, because commonly there is no possible definition for the ideal sustainability and/or the critical value [40].

Even if more research is required to consolidate the biorefineries topic, the next step in Mexico is the knowledge transfer for scaling up of processes. This is not an easy task since many fac-

As said previously, biogas composition depends on the raw materials. The presence of compounds other than methane reduces the calorific value. The elimination of those compounds is a research topic with scientific and technologic interest. There are two main approaches

The increase in the methane grade, known also as upgrading or enrichment, refers to the separation of the methane from the biogas in order to have a compound with higher energy potential. The idea is to recover methane in order to conserve the material representing the

tors should be in synchronization: government, farmers and academic sector.

relating biogas purification: biomethane upgrading and biogas cleaning [41].

highest calorific value in biogas. There are different methods for this effect:

• Adsorption is known as pressure swing adsorption (PSA).

*3.4.2. Biogas purification*

30 Biofuels - State of Development

• Absorption with water traps.

Concerning biogas cleaning, the issues are related with the elimination of corrosive compounds, which affect the equipment used in the energy generation stage. Among the harmful agents, most commonly found in biogas are sulfur and nitrogen compounds. Methods to remove these chemical compounds are studied. The compound that receives most attention is H<sup>2</sup> S due to its impact on the mechanical parts of the devices as well as on the environment:


Biogas cleaning and upgrading is few addressed in Mexico; however, it is an important issue which could diversify the use of biogas and even to promote the transformation of agriculture waste into biogas.

#### *3.4.3. Technology development*

Although there is some equipment designed for national entrepreneurs, most of the commercial technology associated to the biogas life cycle is foreign. At present time, commercial globalization and the international free trade agreements allow to get low prices for several products. However, since the biogas topic is not really spread at small and medium size, the importation of technology increases the initial investment for projects.

Then, the development of technology is a topic which should be addressed in Mexico, especially for small applications such as burners, furnaces, stoves, lamps, small engines for mechanical energy, and power plants for a generation less than 30 kW.

Due to the geographic characteristic of the country, the production of agriculture wastes is not uniformly distributed. This implies an additional issue on the collection stage for large size biogas facilities. Then, it is advisable to consider a distributed generation approach; that means, to implement small-scale facilities transforming small quantities of biomass and producing small quantities of energy, but near to the final users. This allows a better management of resources. Then, the distributed structures are designed to avoid logistic problems for transportation which demand energy, time and other resources. For this reason, the availability of technology for medium and small size is an important aspect to be considered.

#### *3.4.4. Energy crops*

Energy crops should be also a developing topic for biogas production, preferentially in biorefinery schemes.

Currently, there exist around 5 nopal (*Opuntia*) crops for electricity production; the selected plant is not edible specie which has been modified to eliminate thorns and make it easier to handle. Also, some studies have been carried out to evaluate the potential of the species *Opuntia* spp. for the production of biofuels. It has been reported that 1 ha of nopal can produce more than 100 t of biomass [42]. Experimental results show that a methane content of more than 70% can be achieved when a mixture of nopal and manure is used in a 3:1 ratio at a temperature of 30°C. Another study indicates a biogas production of 0.861 m<sup>3</sup> kg−1 of volatile solids with 58.2% of methane [43, 44].

**Author details**

**References**

Salvador Carlos Hernandez\* and Lourdes Diaz Jimenez

Revaloración de Residuos, Ramos Arizpe, Mexico

10.1016/j.rser.2015.02.032

\*Address all correspondence to: salvador.carlos@cinvestav.mx

Cinvestav Saltillo, Sustentabilidad de los Recursos Naturales y Energía, Laboratorio de

The Potential for Biogas Production from Agriculture Wastes in Mexico

http://dx.doi.org/10.5772/intechopen.75457

33

[1] Ch M, Feng Y, Wang X, Ren G. Review on research achievements of biogas from anaerobic digestion. Renewable and Sustainable Energy Reviews. 2015;**45**:540-555. DOI:

[2] Zhang Q, Hu J, Lee D-J. Biogas from anaerobic digestion processes: Research updates.

[3] Fagbohungbe MO, Herbert BMJ, Hurst L, Ibeto CN, Li H, Usmani SQ, Semple KT. The challenges of anaerobic digestion and the role of biochar in optimizing anaerobic diges-

[4] Sawatdeenarunat C, Surendra KC, Takara D, Oechsner H, Kumar-Khanal S. Anaerobic digestion of lignocellulosic biomass: Challenges and opportunities. Bioresources

[5] Paudel SR, Banjara SP, Choi OK, Park KY, Kim YM, Lee JW. Pretreatment of agricultural biomass for anaerobic digestion: Current state and challenges. Bioresources Technology.

[6] Hagos K, Zong J, Li D, Liu C, Lu X. Anaerobic co-digestion process for biogas production: Progress, challenges and perspectives. Renewable and Sustainable Energy Reviews.

[7] Gustavsson J, Cederberg C, Sonesson U. van Otterdijk R, Meybec A. Pérdidas y desperdicios de alimentos en el mundo. Alcance, causas y prevención. Rome, Italy: FAO; 2012.

[8] Dupuis I. Estimación de los residuosagrícolasgenerados en la isla de Tenerife. Tenerife: ServicioTécnico de Agricultura y Desarrollo Rural; 2006 20 p. DOI: www.agrocabildo.

[9] Smil V. Crop residues: Agriculture's largest harvest: Crop residues incorporate more than half of the world's agricultural phytomass. Bioscience. 1999;**94**(4):299-308. DOI:

[10] Barres Benlloch T. Producción y consumosostenibles y residuosagrarios. Madrid, Spain: Ministerio de Agricultura, Alimentación y MedioAmbiente; 2012. 93 p. DOI: www.mapama. gob.es/es/calidad-y-evaluacion-ambiental/publicaciones/residuos\_agrarios\_tcm7-

tion. Waste Management. 2017;**61**:236-249. DOI: 10.1016/j.wasman.2016.11.028

Renewable Energy. 2016;**98**:108-119. DOI: 10.1016/j.renene.2016.02.029

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org/publica/Publicaciones/sost\_28\_L\_estima\_residu\_agricola.pdf

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33 p. DOI: www.fao.org/3/a-i2697s.pdf

10.2307/1313613

232332

On the other side, algae have been also identified as feasible plants for energy crops [45]. In Mexico, this raw material is mainly studied for the production of hydrogen, biodiesel and bioethanol. The production of biogas from algae is little studied; however, the potential is important, especially in biorefinery schemes. Currently, different laboratory experiments have been carried out using substrates that include algae. Different aspects of the transformation are considered such as the sequestration of carbon dioxide (CO2 ) from different industrial emissions to use as a nutrient in the growth of algae, the selection of the site for the installation of biorefineries as well as transportation costs [46]. Other project is developed in order to evaluate the performance of a biorefinery at laboratory and pilot plant level producing biogas, biodiesel from microalgae and hydrogen from algae residues, using municipal wastewater.

There are different plants which could be produced in energy crops such as jatropha, moringa, savage castor oil plant and others. Even if these plants do not involve a direct food competition, they induce an indirect food competition due to the soil and resources requirements. For these reasons, more studies should be addressed in order to take appropriate decisions concerning the implementation of energy crops.

#### **4. Conclusions**

Among more than 300 species cultivated in Mexico, 39 were selected for this assessment due to its characteristics, production amount and availability for biogas production. It was deduced that around 12.7 Mt of wastes available for biogas are produced. From those wastes, a total of 450 GWh could be produced from these wastes.

Currently, the generation of energy from agricultural wastes is less than 10% of the estimated potential.

The main applications of biogas are thermal and electric energy generation. However, some other potential applications should be explored, such as light and heat for cooking at low size and the obtaining of added value products from biorefinery schemes at larger scales.

It is important to remark that a national strategy is required to take advantage of the potential of biogas. Some independent efforts have been done: government has promoted new legislations to motivate the development of biofuels; academic sector addressed from different perspectives the knowledge generation related to bioenergy; enterprises are searching for alternatives to implement bioenergy projects. However, an integrated strategy is necessary for more strong and efficient collaboration. The adequate transfer of technology and knowledge is essential, which requires a dynamic collaboration between academy, productive sector and government.

#### **Author details**

Currently, there exist around 5 nopal (*Opuntia*) crops for electricity production; the selected plant is not edible specie which has been modified to eliminate thorns and make it easier to handle. Also, some studies have been carried out to evaluate the potential of the species *Opuntia* spp. for the production of biofuels. It has been reported that 1 ha of nopal can produce more than 100 t of biomass [42]. Experimental results show that a methane content of more than 70% can be achieved when a mixture of nopal and manure is used in a 3:1 ratio at a temperature of 30°C. Another study indicates a biogas production of 0.861 m<sup>3</sup> kg−1 of volatile

On the other side, algae have been also identified as feasible plants for energy crops [45]. In Mexico, this raw material is mainly studied for the production of hydrogen, biodiesel and bioethanol. The production of biogas from algae is little studied; however, the potential is important, especially in biorefinery schemes. Currently, different laboratory experiments have been carried out using substrates that include algae. Different aspects of the transforma-

emissions to use as a nutrient in the growth of algae, the selection of the site for the installation of biorefineries as well as transportation costs [46]. Other project is developed in order to evaluate the performance of a biorefinery at laboratory and pilot plant level producing biogas, biodiesel from microalgae and hydrogen from algae residues, using municipal wastewater. There are different plants which could be produced in energy crops such as jatropha, moringa, savage castor oil plant and others. Even if these plants do not involve a direct food competition, they induce an indirect food competition due to the soil and resources requirements. For these reasons, more studies should be addressed in order to take appropriate decisions

Among more than 300 species cultivated in Mexico, 39 were selected for this assessment due to its characteristics, production amount and availability for biogas production. It was deduced that around 12.7 Mt of wastes available for biogas are produced. From those wastes,

Currently, the generation of energy from agricultural wastes is less than 10% of the estimated

The main applications of biogas are thermal and electric energy generation. However, some other potential applications should be explored, such as light and heat for cooking at low size

It is important to remark that a national strategy is required to take advantage of the potential of biogas. Some independent efforts have been done: government has promoted new legislations to motivate the development of biofuels; academic sector addressed from different perspectives the knowledge generation related to bioenergy; enterprises are searching for alternatives to implement bioenergy projects. However, an integrated strategy is necessary for more strong and efficient collaboration. The adequate transfer of technology and knowledge is essential, which requires a dynamic collaboration between academy, productive sector and government.

and the obtaining of added value products from biorefinery schemes at larger scales.

) from different industrial

tion are considered such as the sequestration of carbon dioxide (CO2

solids with 58.2% of methane [43, 44].

32 Biofuels - State of Development

concerning the implementation of energy crops.

a total of 450 GWh could be produced from these wastes.

**4. Conclusions**

potential.

Salvador Carlos Hernandez\* and Lourdes Diaz Jimenez

\*Address all correspondence to: salvador.carlos@cinvestav.mx

Cinvestav Saltillo, Sustentabilidad de los Recursos Naturales y Energía, Laboratorio de Revaloración de Residuos, Ramos Arizpe, Mexico

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**Chapter 3**

**Provisional chapter**

**Biomethane as Transport Fuel**

**Biomethane as Transport Fuel**

Ewa Krasuska

**Abstract**

and use, e.g., Poland.

alternative fuels is a short-term solution.

Germany, Europe

**1. Introduction**

Ewa Krasuska

Magdalena Rogulska, Paweł Bukrejewski and

Magdalena Rogulska, Paweł Bukrejewski and

DOI: 10.5772/intechopen.75173

In the European Union (EU), the demand for energy in transport is growing, and at the same time, transport is almost entirely dependent on oil and is responsible for more than 30% of greenhouse gas (GHG) emissions in Europe. Biomethane is one of promising options for sustainable mobility. Technical requirements applied for biomethane in transport in both countries and at the EU level are presented as well as short overview of the main upgrading technologies. Sweden and Germany may serve as examples of effective implementation of biomethane in transport sector; however, it is done in different ways (Sweden (non-grid transport use) and Germany (mainly via injection to gas grid)). Their experience can be useful for countries starting development of biomethane production

**Keywords:** biomethane, transport, quality requirements, good practices, Sweden,

In the European Union (EU), the demand for energy in transport is growing, and at the same time transport is almost entirely dependent on oil and is responsible for more than 30% of greenhouse gas (GHG) emissions in Europe, and related emissions will double by 2050 [1]. In the medium and long term, significant changes are needed regarding transport means (sustainable mobility); the implementation of biofuels (including biomethane) and renewable

> © 2016 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution,

© 2018 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use,

distribution, and reproduction in any medium, provided the original work is properly cited.

and reproduction in any medium, provided the original work is properly cited.

Experts' reports prepared at the request of the European Commission (EC) clearly indicate natural gas and its renewable equivalent, biomethane, as a bridging fuel between conventional

Additional information is available at the end of the chapter

Additional information is available at the end of the chapter

http://dx.doi.org/10.5772/intechopen.75173


#### **Chapter 3 Provisional chapter**

#### **Biomethane as Transport Fuel Biomethane as Transport Fuel**

Magdalena Rogulska, Paweł Bukrejewski and Ewa Krasuska Magdalena Rogulska, Paweł Bukrejewski and Ewa Krasuska

Additional information is available at the end of the chapter Additional information is available at the end of the chapter

http://dx.doi.org/10.5772/intechopen.75173

#### **Abstract**

and agro-industrial wastes. Chemical Engineering Research and Design. 2016;**107**:195-

[36] Sanchez A, Valdez-Vazquez I, Soto A, Sánchez S, Tavarez D. Lignocellulosic n-butanol co-production in an advanced biorefinery using mixed cultures. Biomass and Bioenergy.

[37] Santos-Panqueva Y, Guerrero-Fajardo CA, Cuevas Rodríguez EO, Picos-Corrales LA, Silva CM, Contreras-Andrade I. Production of bio-ethylene from wastes of microalgae to biodiesel biorefinery. Waste Biomass Valor. 2017. DOI: 10.1007/s12649-017-0064-1 [38] Carrillo-Nievez D, Ruiz HA, Aguilar CN, Ilyina A, Parra-Saldívar R, Torres JA, Martínez Hernández JL. Process alternatives for bioethanol production from mango stem bark residues. Bioresource Technology. 2017;**239**:430-436. DOI: 10.1016/j.biortech.2017.04.131

[39] Marone A, Ayala-Campos OR, Trably E, Carmona-Martínez AA, Moscoviz R, Latrille E, Steyer J-P, Alcaráz-González V, Bernet N. Coupling dark fermentation and microbial electrolysis to enhance bio-hydrogen production from agro-industrial wastewaters and by-products in a bio-refinery framework. International. Journal of Hydrogen Energy.

[40] Sacramento-Rivero J, Navarro-Pineda F, Vilchiz-Bravo LE. Evaluating the sustainability of biorefineries at the conceptual design stage. Chemical Engineering Research and

[41] Miltner M, Makaruk A, Harasek M. Review on available biogas upgrading technologies and innovations towards advanced solutions. Journal of Cleaner Production.

[42] Varnero MT, García de Cortázar V. Producción de bioenergía y fertilizantes a partir de los nopales. In: Sáenz C, Rosell C, editors. Utilizaciónagroindustrialdelnopal. Boletín de ServiciosAgrícolas de la FAO 162. Rome, Italy: FAO; 2006. pp. 113-120. DOI: www.fao.

[43] Uribe JM, Varnero MT, Benavides C. Biomass of prickly pear (*Opuntia ficus-indica* L. mill)

[44] Obach J, Lemus MP. Bioenergy generation using *Opuntia ficus-indica* in arid and semiarid zones of developing countries. In: Proceedings of international symposium on energy from biomass and waste; November 2006; Venice, Italy. International waste

[45] Patiño R. Las Algas. In: La producción de biocombustibles y susimpactos: estudio de

[46] Rodríguez-Picos I, Rubio-Castro E, Ortiz-del-Castillo JR, Hernández-Calderón OM, Serna-González M, Ponce-Ortega PO. Diseñoóptimo de biorefineríasutilizandobiomasa de algas. In: Proceedings of the XXXIV EncuentroNacional y III CongresoInternacional de la AMIDIQ; 7-10 May 2013; Mazatlan, Mexico. Academia Mexicana de Investigación

as bovine manure anaerobic digestion accelerator. Simiente. 1992;**62**(1):1-14

117. DOI: 10.1016/j.cherd.2015.10.041

36 Biofuels - State of Development

2017;**102**:1-12. DOI: 10.1016/j.biombioe.2017.03.023

2017;**42**:1609-1621. DOI: 10.1016/j.ijhydene.2016.09.166

Design. 2016;**107**:167-180. DOI: 10-1016/j.cherd.2015.10.017

2017;**161**:1329-1337. DOI: 10.1016/j.jclepro.2017.06.045

org/docrep/009/a0534s/a0534s00.htm

casos. La Habana, Cuba: Cyted; 2011. pp. 78-86

y Docencia en IngenieríaQuímica; 2013. pp. 1278-1283

working Group; 2006

In the European Union (EU), the demand for energy in transport is growing, and at the same time, transport is almost entirely dependent on oil and is responsible for more than 30% of greenhouse gas (GHG) emissions in Europe. Biomethane is one of promising options for sustainable mobility. Technical requirements applied for biomethane in transport in both countries and at the EU level are presented as well as short overview of the main upgrading technologies. Sweden and Germany may serve as examples of effective implementation of biomethane in transport sector; however, it is done in different ways (Sweden (non-grid transport use) and Germany (mainly via injection to gas grid)). Their experience can be useful for countries starting development of biomethane production and use, e.g., Poland.

DOI: 10.5772/intechopen.75173

**Keywords:** biomethane, transport, quality requirements, good practices, Sweden, Germany, Europe

#### **1. Introduction**

In the European Union (EU), the demand for energy in transport is growing, and at the same time transport is almost entirely dependent on oil and is responsible for more than 30% of greenhouse gas (GHG) emissions in Europe, and related emissions will double by 2050 [1]. In the medium and long term, significant changes are needed regarding transport means (sustainable mobility); the implementation of biofuels (including biomethane) and renewable alternative fuels is a short-term solution.

Experts' reports prepared at the request of the European Commission (EC) clearly indicate natural gas and its renewable equivalent, biomethane, as a bridging fuel between conventional

fuels and advanced biofuels of the next generations [2]. Methane fuels are perceived as an important supplement to the fuel market, especially during the transition period between the first generation of liquid biofuels and the commercial implementation of advanced biofuels.

Option 2 is feeding biomethane into the grid of natural gas; then, a mixture of biomethane and natural gas is supplied to filling stations. This technical solution is very common, for example, in Germany, where the grid of natural gas is well developed and a significant number of CNG filing stations are established. In option 3 biomethane is transported by a local infrastructure to a filling station—a dedicated biomethane pipeline is constructed. In option 4 compressed biomethane is transported in containers via road vehicles to the filling station. Options 3 and

In many European countries, the production and use of biomethane have increased within the last 10 years. In the end of 2016, biomethane was produced in nearly 500 plants in 16 countries [7, 8]. Germany is still the biggest European biomethane producer, the United Kingdom (UK) with 80 running plants has become the second largest biomethane producer, and Sweden is in third position. In the UK nearly all the plants have been created in the last 5 years due to extensive support policies, such as the introduction of an attractive Renewable Heat Incentive (RHI) providing a bonus paid on top of the market value of the

In the following subsections, more details will be provided on biomethane markets in Germany (as the European leader in biomethane production) and Sweden (as the European leader in the

Germany has a strong biogas industry with more than 10,000 biogas plants and is the EU leading country in terms of biomethane production. In 2016 there were 193 biomethane plants

German gas grid. This contributes to about 12.3% of the natural gas production or 1% of natu-

Biomethane fed into the gas grid is primarily used in CHP systems for combined heat and power production, i.e., more than 90% of total biomethane volumes, about 4% is used for transport sector and 3.5% for heat production. In Germany there are currently (September 2017) about 900 CNG filling stations which sell a mixture of natural gas and biomethane with different mixture ratios [11]. The current total number of NGV amounts at some 100,000.

One interesting example of promoting biomethane as a transport fuel is in Berlin. Biogas production from 60,000 tons of selectively collected biowaste from households is upgraded into

Biomethane has higher production costs than natural gas. The support for biomethane market in Germany is realized particularly in the electricity sector which was the key driver for development of biogas installations in recent years [5]. Currently, feed-in tariff is offered for

of raw

of biomethane fed into the

Biomethane as Transport Fuel

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connected to the natural gas grid with a total estimated capacity of 1.71 billion m3

biogas processed [10]. It is an equivalent to about 940 million m3

biomethane, which is used to fuel 150 waste collection tracks [11].

**2. Examples of biomethane markets in selected EU countries**

4 are common in Sweden.

gas injected [9].

transport use of biomethane).

**2.1. Biomethane in Germany**

ral gas consumption in Germany.

Biogas upgraded to the quality of natural gas—**biomethane**—has the same advantages as natural gas but is more friendly for the environment from sustainable point of view (higher reduction of GHG emissions, use of local substrates, positive link with waste management). Several European projects (GasHighWay [3], Biogasmax [4], Biomaster, etc.) have shown that biomethane produced and used locally has a positive impact on local sustainable development (reduction of negative impacts connected with transport sector such as smog, creation of new markets, generation of news jobs, etc.). Biomethane and natural gas are recommended as fuels in urban traffic; the advantages of methane fuels related to noise reduction and emissions of harmful substances predispose them to be used in such fleets of vehicles as buses, municipal and delivery vehicles, and taxis. Moreover, biomethane is currently the only biofuel with the same chemical composition as the fossil fuel it replaces. It can therefore be mixed with natural gas in any ratio, without negative consequences for the engine.

In the EU about 11% of energy of the produced biogas is used for transport sector [5]. In 2015 in Sweden, the use of biomethane for vehicles amounted to 1124 GWh and in Germany 580 GWh, respectively. Globally, the leading position belongs to the United States with the use of biomethane for vehicles twice more compared to Sweden [6].

#### **1.1. Technical options for natural gas vehicle (NGV) filling with biomethane**

Biomethane for transport can be used in several different technical options, as presented in **Figure 1**. Option 1 is a biomethane filling station established directly at the biomethane plant.

**Figure 1.** Technical options of filling biomethane for vehicles.

Option 2 is feeding biomethane into the grid of natural gas; then, a mixture of biomethane and natural gas is supplied to filling stations. This technical solution is very common, for example, in Germany, where the grid of natural gas is well developed and a significant number of CNG filing stations are established. In option 3 biomethane is transported by a local infrastructure to a filling station—a dedicated biomethane pipeline is constructed. In option 4 compressed biomethane is transported in containers via road vehicles to the filling station. Options 3 and 4 are common in Sweden.

#### **2. Examples of biomethane markets in selected EU countries**

In many European countries, the production and use of biomethane have increased within the last 10 years. In the end of 2016, biomethane was produced in nearly 500 plants in 16 countries [7, 8]. Germany is still the biggest European biomethane producer, the United Kingdom (UK) with 80 running plants has become the second largest biomethane producer, and Sweden is in third position. In the UK nearly all the plants have been created in the last 5 years due to extensive support policies, such as the introduction of an attractive Renewable Heat Incentive (RHI) providing a bonus paid on top of the market value of the gas injected [9].

In the following subsections, more details will be provided on biomethane markets in Germany (as the European leader in biomethane production) and Sweden (as the European leader in the transport use of biomethane).

#### **2.1. Biomethane in Germany**

fuels and advanced biofuels of the next generations [2]. Methane fuels are perceived as an important supplement to the fuel market, especially during the transition period between the first generation of liquid biofuels and the commercial implementation of advanced biofuels. Biogas upgraded to the quality of natural gas—**biomethane**—has the same advantages as natural gas but is more friendly for the environment from sustainable point of view (higher reduction of GHG emissions, use of local substrates, positive link with waste management). Several European projects (GasHighWay [3], Biogasmax [4], Biomaster, etc.) have shown that biomethane produced and used locally has a positive impact on local sustainable development (reduction of negative impacts connected with transport sector such as smog, creation of new markets, generation of news jobs, etc.). Biomethane and natural gas are recommended as fuels in urban traffic; the advantages of methane fuels related to noise reduction and emissions of harmful substances predispose them to be used in such fleets of vehicles as buses, municipal and delivery vehicles, and taxis. Moreover, biomethane is currently the only biofuel with the same chemical composition as the fossil fuel it replaces. It can therefore be mixed

with natural gas in any ratio, without negative consequences for the engine.

**1.1. Technical options for natural gas vehicle (NGV) filling with biomethane**

use of biomethane for vehicles twice more compared to Sweden [6].

38 Biofuels - State of Development

**Figure 1.** Technical options of filling biomethane for vehicles.

In the EU about 11% of energy of the produced biogas is used for transport sector [5]. In 2015 in Sweden, the use of biomethane for vehicles amounted to 1124 GWh and in Germany 580 GWh, respectively. Globally, the leading position belongs to the United States with the

Biomethane for transport can be used in several different technical options, as presented in **Figure 1**. Option 1 is a biomethane filling station established directly at the biomethane plant.

> Germany has a strong biogas industry with more than 10,000 biogas plants and is the EU leading country in terms of biomethane production. In 2016 there were 193 biomethane plants connected to the natural gas grid with a total estimated capacity of 1.71 billion m3 of raw biogas processed [10]. It is an equivalent to about 940 million m3 of biomethane fed into the German gas grid. This contributes to about 12.3% of the natural gas production or 1% of natural gas consumption in Germany.

> Biomethane fed into the gas grid is primarily used in CHP systems for combined heat and power production, i.e., more than 90% of total biomethane volumes, about 4% is used for transport sector and 3.5% for heat production. In Germany there are currently (September 2017) about 900 CNG filling stations which sell a mixture of natural gas and biomethane with different mixture ratios [11]. The current total number of NGV amounts at some 100,000.

> One interesting example of promoting biomethane as a transport fuel is in Berlin. Biogas production from 60,000 tons of selectively collected biowaste from households is upgraded into biomethane, which is used to fuel 150 waste collection tracks [11].

> Biomethane has higher production costs than natural gas. The support for biomethane market in Germany is realized particularly in the electricity sector which was the key driver for development of biogas installations in recent years [5]. Currently, feed-in tariff is offered for

systems with a capacity of up to 100 kW and a market premium for systems with a capacity up to 20 MW. The change in the past feed-in tariff system of 2011 resulted in a strong fall in the development of new installations.

Biomethane is the very interesting option with a lot of opportunities for municipalities, because local governments are responsible, among others, for waste management (biowastes—the potential source of biogas) and municipal services such as transport (potential user of biomethane as a fuel). Therefore, they have possibilities to create local supply and demand. Municipalities can use locally produced fuel in their own vehicles, municipal buses, and waste trucks. Swedish experience showed that municipalities were creating local markets with a lot

Biomethane as Transport Fuel

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Besides using their existing companies, municipalities were active in establishment of new ones for this sector, e.g., gas enterprises Svensk Biogas and Fordonsgas. Local governments implemented effectively public purchasing policy not only for procurements of vehicle purchases (e.g., city buses and waste trucks) but also for municipal services. New expertise has arisen for local enterprises—production of equipment for upgrading systems (e.g., Malmberg,

In the regions of Västra Götaland (Western Sweden) and Skåne (Southern Sweden), the impressive development of the biogas sector resulted from a unique interaction between research, local governments, and industrial partners [19, 20]. Their experience may be used as an example of good practices in developing local biogas and biomethane deployment strate-

In Kristianstad (capital of Skåne), digestion of organic matter into biogas has become the most important way to reduce the negative environmental impacts of waste and instead use it as an energy resource. The biogas plant, as well as the units for upgrading gas, is owned by the municipal company, Kristianstad Biogas, which is a part of the municipal energy company. In **Figure 2** biomethane filling station for buses located nearby Kristianstad biogas plant is presented. The municipality is aiming to have a fossil fuel free fleet by 2020, mainly running on

Purac) and production of gas engines and vehicles (e.g., Scania and Volvo).

of benefits for their communities [17, 18].

gies in other regions and countries, e.g., in Poland.

**Figure 2.** Biomethane filling station for buses in Kristianstad (photo by M. Rogulska).

biogas [21].

In transport sector a tax reduction is offered till 2018 for the use of natural gas; however, for biomethane used as a transport fuel, no tax benefits are granted since January 2016 [12]. There is also no incentive to feed-in biomethane into the natural gas grid anymore. The main instrument in the transport sector in Germany is currently the GHG quota, which in 2015 replaced the biofuel quota obligation [11]. The GHG quota is an annual target for GHG emission reduction as a "decarbonization strategy" for transport sector. The use of biomethane offers a mean to achieve this. Biomethane and other biofuels have to fulfill the national regulations established by the Biofuel Sustainability Ordinance.

With regard to a relatively slow rate of the GHG emission reduction in the transportation sector, the German government gave more attention to the increased use of natural gas and biomethane for transport. The Round Table for Natural Gas Mobility set a goal to reach 4% share of natural gas in transport by 2020 and 20% share of biomethane in the natural gas used for transport [12].

#### **2.2. Biomethane in Sweden**

Biomethane has quickly found a place in Sweden because Sweden's natural gas prices have always been higher than in Europe and Sweden does not have an extensive gas network.

Sweden has well developed non-grid-based transportation of biomethane. The biomethane is transported mainly not only in compressed form in mobile storage units but also in liquefied form or by local gas grids [13].

In Sweden the most of the biogas is produced from sewage treatment plants, and the amount of landfill gas decreases due to EU regulations (since 2005, the ban on landfill for organic waste has been in force in Sweden). The growing sector is centralized biogas plants that process organic waste, including food waste separated at the source [14]. Food waste collection is growing: in 2016 already 212 municipalities from 290 introduced such systems.

In Sweden natural gas and biomethane are complementary fuels; in 2016 almost 70% of the produced biogas was upgraded and used as transport fuel. In the end of 2016, there were in the operation 62 biogas upgrading plants: 43 water scrubbers, 6 PSA, 11 amine scrubbers, and 2 membrane units [15].

At the end of 2016, Swedish natural gas vehicle (NGV) fleet had 54,439 light duty vehicles, 2331 buses (18% of national market), and 821 HD trucks (in that 50 LNG trucks) [15].

Sweden as the first country in Europe has reported to the European Commission the consumption of biomethane in transport in the annual reports on the implementation of the biofuel directive (2003/30/EC) to the European Commission [16].

Biomethane is the very interesting option with a lot of opportunities for municipalities, because local governments are responsible, among others, for waste management (biowastes—the potential source of biogas) and municipal services such as transport (potential user of biomethane as a fuel). Therefore, they have possibilities to create local supply and demand. Municipalities can use locally produced fuel in their own vehicles, municipal buses, and waste trucks. Swedish experience showed that municipalities were creating local markets with a lot of benefits for their communities [17, 18].

systems with a capacity of up to 100 kW and a market premium for systems with a capacity up to 20 MW. The change in the past feed-in tariff system of 2011 resulted in a strong fall in

In transport sector a tax reduction is offered till 2018 for the use of natural gas; however, for biomethane used as a transport fuel, no tax benefits are granted since January 2016 [12]. There is also no incentive to feed-in biomethane into the natural gas grid anymore. The main instrument in the transport sector in Germany is currently the GHG quota, which in 2015 replaced the biofuel quota obligation [11]. The GHG quota is an annual target for GHG emission reduction as a "decarbonization strategy" for transport sector. The use of biomethane offers a mean to achieve this. Biomethane and other biofuels have to fulfill the national regulations estab-

With regard to a relatively slow rate of the GHG emission reduction in the transportation sector, the German government gave more attention to the increased use of natural gas and biomethane for transport. The Round Table for Natural Gas Mobility set a goal to reach 4% share of natural gas in transport by 2020 and 20% share of biomethane in the natural gas used

Biomethane has quickly found a place in Sweden because Sweden's natural gas prices have always been higher than in Europe and Sweden does not have an extensive gas network.

Sweden has well developed non-grid-based transportation of biomethane. The biomethane is transported mainly not only in compressed form in mobile storage units but also in liquefied

In Sweden the most of the biogas is produced from sewage treatment plants, and the amount of landfill gas decreases due to EU regulations (since 2005, the ban on landfill for organic waste has been in force in Sweden). The growing sector is centralized biogas plants that process organic waste, including food waste separated at the source [14]. Food waste collection is

In Sweden natural gas and biomethane are complementary fuels; in 2016 almost 70% of the produced biogas was upgraded and used as transport fuel. In the end of 2016, there were in the operation 62 biogas upgrading plants: 43 water scrubbers, 6 PSA, 11 amine scrubbers, and

At the end of 2016, Swedish natural gas vehicle (NGV) fleet had 54,439 light duty vehicles,

Sweden as the first country in Europe has reported to the European Commission the consumption of biomethane in transport in the annual reports on the implementation of the bio-

2331 buses (18% of national market), and 821 HD trucks (in that 50 LNG trucks) [15].

fuel directive (2003/30/EC) to the European Commission [16].

growing: in 2016 already 212 municipalities from 290 introduced such systems.

the development of new installations.

40 Biofuels - State of Development

lished by the Biofuel Sustainability Ordinance.

for transport [12].

**2.2. Biomethane in Sweden**

form or by local gas grids [13].

2 membrane units [15].

Besides using their existing companies, municipalities were active in establishment of new ones for this sector, e.g., gas enterprises Svensk Biogas and Fordonsgas. Local governments implemented effectively public purchasing policy not only for procurements of vehicle purchases (e.g., city buses and waste trucks) but also for municipal services. New expertise has arisen for local enterprises—production of equipment for upgrading systems (e.g., Malmberg, Purac) and production of gas engines and vehicles (e.g., Scania and Volvo).

In the regions of Västra Götaland (Western Sweden) and Skåne (Southern Sweden), the impressive development of the biogas sector resulted from a unique interaction between research, local governments, and industrial partners [19, 20]. Their experience may be used as an example of good practices in developing local biogas and biomethane deployment strategies in other regions and countries, e.g., in Poland.

In Kristianstad (capital of Skåne), digestion of organic matter into biogas has become the most important way to reduce the negative environmental impacts of waste and instead use it as an energy resource. The biogas plant, as well as the units for upgrading gas, is owned by the municipal company, Kristianstad Biogas, which is a part of the municipal energy company. In **Figure 2** biomethane filling station for buses located nearby Kristianstad biogas plant is presented. The municipality is aiming to have a fossil fuel free fleet by 2020, mainly running on biogas [21].

**Figure 2.** Biomethane filling station for buses in Kristianstad (photo by M. Rogulska).

## **3. Technical requirements for biomethane use in transport**

Development of **technical standards** is important for market introduction of advanced biofuels, in that biomethane. Standards for biomethane need to meet not only requirements of automotive industry and vehicle users but also requirements of the natural gas sector.

corrosive components and variable pressure caused by fuel consumption and subsequent refilling of the fuel tank can cause metal cracks leading to damage and failure. Liquid water

• The content of *oil* in supplied gas should not have an adverse effect on the safe operation of the vehicle. If necessary, filters and separators can be used. A small amount of oil can have

• *Oxygen* together with hydrogen sulfide can react, in particular with copper, which is detri-

Minimizing the content of pollutants to the limit values given in the standards is important

Sweden has developed a standard for biomethane as a fuel; it has included biomethane in its legal regulations on transport fuels. The Swedish standard SS 155438 "Motor fuels – Biogas as fuel for high-speed Otto engines" developed in 1999 was the first standard regulating the use

The guidelines contained therein are presented in **Table 1**. Values for type A biometric relate to fuel for engines without regulation of the lambda mixture composition ratio used in heavy vehicles, such as trucks and buses. Values for type B biomethane relate to fuel for engines with controlled mixture composition, used for stoichiometric combustion, e.g., passenger cars [23].

**A)**

4.0 1.0

% vol. % vol.

)

0°C t-5 t-5

mg/m3 20 20

**Biomethane (type** 

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**B)**

5.0 1.0

can also be harmful, creating liquid or permanent blockages in the fuel system.

a beneficial effect on tank protection and lubrication of the injectors.

due to their unfavorable effect on the combustion process in car engines.

of biomethane as a fuel for vehicles in European countries [16, 23].

**Parameter Unit Biomethane (type** 

The Wobbe index MJ/m<sup>3</sup> 44.7–46.4 43.9–47.3 Methane content % vol. 97 ± 1 97 ± 2

The maximum water content mg/m3 32 32

Maximum total sulfur content mg/m3 23 23

The maximum particle size μm 1 1

• The supplied gas fuel should be technically *dust*-free.

mental to the installation.

**3.1. Swedish technical regulations**

Dew point at the highest storage pressure (t—the lowest

content

Total maximum content of nitrogen compounds (excluding N<sup>2</sup>

**Table 1.** Swedish requirements for biomethane use in transport [23].

average daily temperature over the month)

The maximum CO2 + O2 + N<sup>2</sup>

with oxygen maximum

calculated as NH3

For the use of natural gas and biomethane in transport especially, following issues are important [22]:


corrosive components and variable pressure caused by fuel consumption and subsequent refilling of the fuel tank can cause metal cracks leading to damage and failure. Liquid water can also be harmful, creating liquid or permanent blockages in the fuel system.


Minimizing the content of pollutants to the limit values given in the standards is important due to their unfavorable effect on the combustion process in car engines.

#### **3.1. Swedish technical regulations**

**3. Technical requirements for biomethane use in transport**

[22]:

42 Biofuels - State of Development

environmentally troublesome.

vehicles used will operate.

Development of **technical standards** is important for market introduction of advanced biofuels, in that biomethane. Standards for biomethane need to meet not only requirements of

For the use of natural gas and biomethane in transport especially, following issues are important

• *Hydrogen sulfide* as a toxic gas has high corrosive properties. The sulfur contained in it is converted to sulfur oxides, which have a negative impact on the natural environment.

• *Sulfur* has a huge impact on the size and type of exhaust emissions from the car and the corrosive properties of the fuel. Failure to meet the required sulfur content limit shortens the lifetime of the catalyst and consequently, in many modern engines, disruption of the fuel dose control system and problems with proper engine operation. There is also the danger of engine corrosion. Sulfur compounds are among the most technologically and

• *Mercury* has been recognized as a metal that poses a significant threat to the natural environment and human health, and its specific behavior in various ecosystems makes it difficult to fully anticipate the ecological and health effects of contamination with this metal. Mercury in natural gas usually occurs in elemental form, and it can also exist in the form of HgCl2, CH3HgCH3, C2H5HgC2H5, and ClHgCH3. Mercury from aluminum creates

• *Smell*. Natural gas is lighter than air, is colorless, and does not have an odor, so it is odorized with a special chemical that gives it a characteristic smell, to detect even very low concentrations of gas from leaks (before the gas reaches a dangerous concentration in the air). Gas in combination with air can form an explosive mixture. The explosion limit is 5–15%. • *Heat of combustion* is the amount of energy that is released during the combustion of a given substance. If the product of combustion is water vapor, the heat of combustion also includes the heat of condensation of water vapor. Of course, we assume that all fuel will be burned (total combustion) and that combustion is complete (i.e., no combustible substances in the exhaust). When *the heating value* is considered, we are dealing with the same amount of energy, but we do not take into account the condensation of water vapor. As they are similar in terms of definition, but quite different numerically, it is important to pay atten-

• *Water*. The most important safety requirement for BioCNG/CNG is the very low value of the water dew point, excluding the formation of liquid water. For this reason, the water dew point temperature in the gas fuel at the exit from the refueling station should be adequately lower than the lowest ambient temperature at which the refueling station and

• *Liquid water* is a precursor to the formation of corrosive compounds because it combines with natural gas components such as carbon dioxide and hydrogen sulfide. The combination of

amalgams which can cause damage to the materials it comes in contact with.

tion to all tables or statements on which quantity is given.

automotive industry and vehicle users but also requirements of the natural gas sector.

Sweden has developed a standard for biomethane as a fuel; it has included biomethane in its legal regulations on transport fuels. The Swedish standard SS 155438 "Motor fuels – Biogas as fuel for high-speed Otto engines" developed in 1999 was the first standard regulating the use of biomethane as a fuel for vehicles in European countries [16, 23].

The guidelines contained therein are presented in **Table 1**. Values for type A biometric relate to fuel for engines without regulation of the lambda mixture composition ratio used in heavy vehicles, such as trucks and buses. Values for type B biomethane relate to fuel for engines with controlled mixture composition, used for stoichiometric combustion, e.g., passenger cars [23].


**Table 1.** Swedish requirements for biomethane use in transport [23].

#### **3.2. German technical regulations**

In Germany the successful biomethane injection to grid was possible thanks to the fact that clear regulations have been included in the Gas Network Access Ordinance (Gas NZV) [24].

The biomethane supplier is responsible for the warranty of the gas compositions stated in the

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Standardization is important for market access as it brings legal and technical security. Countries producing biomethane have introduced standards, respectively, for injection (e.g., Germany) or vehicle fuel use (e.g., Sweden), but they were very different. To solve this problem, the European Commission (EC) has given to the European Committee for Standardization (CEN) the mandate M/475 for elaboration of European biomethane standards for grid injection and vehicle fuel use. Technical Committee CEN TC 408 formed on this basis started to work in 2011, and final result of their work was published in 2016 (Part 1) and 2017 (Part 2)

Due to the differences in the legal acts and standards regarding the quality of biomethane for transport applications and for injection into the gas grid as well as the expectations of both the gas and automotive industries, it was decided to prepare a standard subdivided into two parts. Developed norms are not looking on the biomethane production pathways (e.g., bio-

In 2016, Part 1 of the European standard EN 16723–2 *Natural gas and biomethane used in transport as well as biomethane injected into the natural gas network* was published. This part concerns

Part 2 published in 2017 refers to the specification for fuels for motor vehicles. This standard specifies the requirements and test methods for natural gas (group L and H), biomethane and blends of both at the point of use as vehicle fuels and applies to these fuels irrespective of the storage state (compressed or liquefied). In **Table 3** requirements, limit values and related test

The technical requirements and safety conditions for the use of biomethane-powered vehicles are identical as those for CNG vehicles, so also their use must be in compliance with regulations and standards such as EN ISO 15403–1:2010: Natural gas—Natural gas for use as a

The standard provides manufacturers, vehicle users, service station operators, and other entities associated with the natural gas vehicle (NGV) industry with information on the quality of fuel for NGV vehicles necessary for the efficient development and operation of gas-fueled

It is recommended that fuels meeting the requirements of this part of ISO 14503 enable:

• To protect the fuel system against corrosion, poisoning, and secretion of sediments or

• To ensure the safe operation of vehicle and equipment used to refuel and service

• To achieve satisfactory operation of the vehicle in all climatic and road conditions

mass fermentation process or gasification process) nor origin of the substrates.

methods for natural gas and biomethane use as vehicle fuel are presented [28].

compressed fuel for vehicles—Part 1: Designation of the quality [22].

the requirements of biomethane injected into the network [27].

worksheets.

[26].

equipment.

liquids

**3.3. European technical regulations**

Technical regulations concerning the quality properties of biomethane and natural gas are provided in worksheets G 260 and G 262 published by the German Technical and Scientific Association for Gas and Water (DVGW)—a standardization body for the gas and water industry [11, 25]. The basic requirements for the quality of gas from renewable sources are given in the worksheet G 262. If the gas is to be fed into the public gas grid, it needs to meet the regulations of DVGW worksheet G 260.

**Table 2** presents the quality requirements for the biogas injection to the gas grid according to DVGW G 260 [25].

Technical requirements for design, construction, and operation of biogas and biogas upgrading installations specify worksheet DVGW G 265. Technical requirements are defined separately for:



**Table 2.** Quality requirements for biomethane injection to grid in Germany [11].

The biomethane supplier is responsible for the warranty of the gas compositions stated in the worksheets.

#### **3.3. European technical regulations**

**3.2. German technical regulations**

44 Biofuels - State of Development

tions of DVGW worksheet G 260.

DVGW G 260 [25].

and drying.

for:

CO2

In Germany the successful biomethane injection to grid was possible thanks to the fact that clear regulations have been included in the Gas Network Access Ordinance (Gas NZV) [24]. Technical regulations concerning the quality properties of biomethane and natural gas are provided in worksheets G 260 and G 262 published by the German Technical and Scientific Association for Gas and Water (DVGW)—a standardization body for the gas and water industry [11, 25]. The basic requirements for the quality of gas from renewable sources are given in the worksheet G 262. If the gas is to be fed into the public gas grid, it needs to meet the regula-

**Table 2** presents the quality requirements for the biogas injection to the gas grid according to

Technical requirements for design, construction, and operation of biogas and biogas upgrading installations specify worksheet DVGW G 265. Technical requirements are defined separately

• Biogas plant: production of biogas from organic raw materials through methane fermentation. • Biogas treatment plant: removal of hydrogen sulfide, carbon dioxide, and other trace gases

• Installations injecting biomethane to the gas grid: calibrated measurement of quality and quantity for billing purposes, if necessary, increases the pressure to the network pressure,

• Recovery systems: an increase in gas pressure in order to transfer to a higher-level network.

< 200 in grid ≤10 bar

In gas grids H < 5

<0.5 injection to wet network

conditioning with liquefied hydrocarbon gas and odorization.

Total sulfur content mg/m3 <8 (short term to <30)

Water content mg/m3 < 50 in grid> 10 bar

content %(v/v) In gas grids L < 10

**Table 2.** Quality requirements for biomethane injection to grid in Germany [11].

Hydrogen content %(v/v) < 2 in exceptional cases to <10

Oxygen content %(v/v) <3 injection to a dry network

**Parameter Unit Value** The Wobbe index MJ/m<sup>3</sup> 48.96–56.52 Heating value MJ/m<sup>3</sup> 30.24–47.16 Relative density 0.55–0.75

Hydrogen sulfide content mg/m3 <5

Standardization is important for market access as it brings legal and technical security. Countries producing biomethane have introduced standards, respectively, for injection (e.g., Germany) or vehicle fuel use (e.g., Sweden), but they were very different. To solve this problem, the European Commission (EC) has given to the European Committee for Standardization (CEN) the mandate M/475 for elaboration of European biomethane standards for grid injection and vehicle fuel use. Technical Committee CEN TC 408 formed on this basis started to work in 2011, and final result of their work was published in 2016 (Part 1) and 2017 (Part 2) [26].

Due to the differences in the legal acts and standards regarding the quality of biomethane for transport applications and for injection into the gas grid as well as the expectations of both the gas and automotive industries, it was decided to prepare a standard subdivided into two parts. Developed norms are not looking on the biomethane production pathways (e.g., biomass fermentation process or gasification process) nor origin of the substrates.

In 2016, Part 1 of the European standard EN 16723–2 *Natural gas and biomethane used in transport as well as biomethane injected into the natural gas network* was published. This part concerns the requirements of biomethane injected into the network [27].

Part 2 published in 2017 refers to the specification for fuels for motor vehicles. This standard specifies the requirements and test methods for natural gas (group L and H), biomethane and blends of both at the point of use as vehicle fuels and applies to these fuels irrespective of the storage state (compressed or liquefied). In **Table 3** requirements, limit values and related test methods for natural gas and biomethane use as vehicle fuel are presented [28].

The technical requirements and safety conditions for the use of biomethane-powered vehicles are identical as those for CNG vehicles, so also their use must be in compliance with regulations and standards such as EN ISO 15403–1:2010: Natural gas—Natural gas for use as a compressed fuel for vehicles—Part 1: Designation of the quality [22].

The standard provides manufacturers, vehicle users, service station operators, and other entities associated with the natural gas vehicle (NGV) industry with information on the quality of fuel for NGV vehicles necessary for the efficient development and operation of gas-fueled equipment.

It is recommended that fuels meeting the requirements of this part of ISO 14503 enable:



water, and other trace constituents. The treatment allows to adjust the quality parameters of

Biomethane as Transport Fuel

47

http://dx.doi.org/10.5772/intechopen.75173

The selection of an effective and economically attractive method for the purification of biogas from compounds that are toxic to the environment and damaging the engines, combined with the adjustment to natural gas parameters, is a key element for the successful introduction of

There are four main types of commercially available biogas upgrading technologies: (i) absorption methods (scrubbing), (ii) membrane separation, (iii) pressure swing adsorption (PSA), and (iv) cryogenic separation. Upgrading should take place with the lowest possible

The share of different biogas upgrading technologies in Europe in the end of 2016 is presented in **Figure 3** [7, 29]. The most popular method of biogas upgrading is water scrubbing, which belongs to absorption methods [8]. Membrane separation is the second most commonly applied technology. Then, chemical scrubbing and PSA come, and the next is physical scrubbing. The cryogenic treatment has so far the lowest market contribution [29]. In Germany, in 2016 taken as a separate year, 11 new upgrading plants were established, of which 6 were different scrubbing methods, 3 membrane separation method, 1 PSA, and 1 biological methanation [30].

The most popular biogas upgrading method is water scrubbing, which is based on the difference of the solubility of CO2 and CH4 in water in lower temperatures. In the water scrubbing column, CO2 dissolves in water, while the concentration of methane in the gas phase increases. In the absorption column, there is also the process of H2S removal. Commonly, raw biogas is compressed to the absorption pressure of 4 to 10 bar and then cooled to increase the efficiency of the gas mixture separation process. Biogas is introduced in the lower part of the column, in which the flowing water absorbs carbon dioxide and hydrogen sulfide. Water is a harmless, low-cost solvent that is easy to handle. In physical scrubbing technologies, organic

biogas to natural gas parameters.

biomethane into the gas grid and/or transport sector.

biomethane losses and low energy input.

**4.1. Water scrubbing and physical scrubbing**

solutions are used (e.g., polyglycol) instead of water.

**Figure 3.** Biogas upgrading technologies in Europe, data for 2016 [7, 29].

a Limit values are absolute, and the number of the decimal places shall not imply the accuracy of the test method.

b A silicon content of <0.1 or 0.5 mg/m3 is considered as a safe level. Further research is needed for a decision whether a higher limit value is acceptable.

c Currently, there is a difference between the automotive industry needs for sulfur content (10 mgS/m<sup>3</sup> including odorization) and the values, and the gas industry can provide (30 mg/m3 including odorization) (see Annex B). It is possible to cover this parameter in a national foreword.

dThe methane number depends on the composition of the distributed natural gas.

e The fuel shall be free from impurities other than "de minimis" levels of compressor oil and dust impurities. In the context of this European standard, "de minimis" means an amount that does not render the fuel unacceptable for use in end-user applications.

**Table 3.** Requirements, limit values, and related test methods for natural gas and biomethane use as vehicle fuel [28].

The operator of the refueling station for vehicles is responsible for any changes in the composition of natural gas supplied to refueling stations to meet these requirements and complements ISO 15403-1.

#### **4. Biogas upgrading technologies**

Biogas upgrading is a process of removing carbon dioxide (CO2 ) from the initial mixture, which increases the methane content (CH4 ) in the gas obtained, and purifying it from hydrogen sulfide, water, and other trace constituents. The treatment allows to adjust the quality parameters of biogas to natural gas parameters.

The selection of an effective and economically attractive method for the purification of biogas from compounds that are toxic to the environment and damaging the engines, combined with the adjustment to natural gas parameters, is a key element for the successful introduction of biomethane into the gas grid and/or transport sector.

There are four main types of commercially available biogas upgrading technologies: (i) absorption methods (scrubbing), (ii) membrane separation, (iii) pressure swing adsorption (PSA), and (iv) cryogenic separation. Upgrading should take place with the lowest possible biomethane losses and low energy input.

The share of different biogas upgrading technologies in Europe in the end of 2016 is presented in **Figure 3** [7, 29]. The most popular method of biogas upgrading is water scrubbing, which belongs to absorption methods [8]. Membrane separation is the second most commonly applied technology. Then, chemical scrubbing and PSA come, and the next is physical scrubbing. The cryogenic treatment has so far the lowest market contribution [29]. In Germany, in 2016 taken as a separate year, 11 new upgrading plants were established, of which 6 were different scrubbing methods, 3 membrane separation method, 1 PSA, and 1 biological methanation [30].

#### **4.1. Water scrubbing and physical scrubbing**

The operator of the refueling station for vehicles is responsible for any changes in the composition of natural gas supplied to refueling stations to meet these requirements and comple-

**Table 3.** Requirements, limit values, and related test methods for natural gas and biomethane use as vehicle fuel [28].

The fuel shall be free from impurities other than "de minimis" levels of compressor oil and dust impurities. In the context of this European standard, "de minimis" means an amount that does not render the fuel unacceptable for use

**Parameter Unit Limit valuesa Test method**

Hydrogen % mol/mol — 2 EN ISO 6974-3

Oxygen % mol/mol — 1 EN ISO 6974 series

S total mgS/m3 <sup>c</sup> EN ISO 6326-5

Compressor oil <sup>e</sup> ISO 8573–2 Amine 10 VDI 2467

Limit values are absolute, and the number of the decimal places shall not imply the accuracy of the test method.

Currently, there is a difference between the automotive industry needs for sulfur content (10 mgS/m<sup>3</sup>

Methane number Index 65d (as in EN

odorization) and the values, and the gas industry can provide (30 mg/m3

dThe methane number depends on the composition of the distributed natural gas.

Total volatile silicon (as Si) mgSi/m3 0.1 or 0.5b EN ISO 16017-1:2000

**Min Max**

°C — −2 (as in EN

mg/m3 — 5 (as in EN

16726)

16726)

16726)

is considered as a safe level. Further research is needed for a decision whether a

TDS-GC-MS

EN ISO 6974-6 EN ISO 6975

ISO 23874 ISO/TR 11150 ISO/TR 12148

EN ISO 6975

EN ISO 6326-1 EN ISO 6326-3 EN ISO 19739

EN ISO 19739

Blatt 2:1991-2008

including odorization) (see Annex B). It is

including

Annex A of EN 16726

) from the initial mixture, which

) in the gas obtained, and purifying it from hydrogen sulfide,

ments ISO 15403-1.

in end-user applications.

Hydrocarbon dew point temperature (from 0.1 to 7 MPa absolute pressure)

46 Biofuels - State of Development

Hydrogen sulfide + carbonyl sulfide

A silicon content of <0.1 or 0.5 mg/m3

higher limit value is acceptable.

(as sulfur)

a

b

c

e

**4. Biogas upgrading technologies**

possible to cover this parameter in a national foreword.

increases the methane content (CH4

Biogas upgrading is a process of removing carbon dioxide (CO2

The most popular biogas upgrading method is water scrubbing, which is based on the difference of the solubility of CO2 and CH4 in water in lower temperatures. In the water scrubbing column, CO2 dissolves in water, while the concentration of methane in the gas phase increases. In the absorption column, there is also the process of H2S removal. Commonly, raw biogas is compressed to the absorption pressure of 4 to 10 bar and then cooled to increase the efficiency of the gas mixture separation process. Biogas is introduced in the lower part of the column, in which the flowing water absorbs carbon dioxide and hydrogen sulfide. Water is a harmless, low-cost solvent that is easy to handle. In physical scrubbing technologies, organic solutions are used (e.g., polyglycol) instead of water.

**Figure 3.** Biogas upgrading technologies in Europe, data for 2016 [7, 29].

The scrubbing technologies assume the regeneration of an aqueous solution (or organic) in the desorption column by depressurizing or passing the stream of air in a countercurrent (stripping). Passing the air stream is not recommended at higher levels of H2 S, because the precipitating elemental sulfur causes operational problems of the installation. The scrubbing technologies in general do not require the supply of heat to the process and the use of chemicals, while they assume heat recovery and minimization of water consumption. Depending on the design of the column, the efficiency of upgrading with water scrubbing method is at the level of 90–99% of pure biomethane in the output gas [11].

gas phase. Adsorption is higher in higher pressures and in low temperatures. Biogas is cooled down to about 70°C and fed into the adsorption column. The biogas must be pre-purified in order to remove hydrogen sulfide and water vapor, which could, however, result in the deactivation of the active bed. The adsorption is a batch process and takes place in several columns.

Biomethane as Transport Fuel

49

http://dx.doi.org/10.5772/intechopen.75173

Cryogenic separation is a new biogas upgrading technology. The process takes place under conditions of very low temperatures (up to −100°C) and high pressures (40 bar). Carbon dioxide condenses or sublimes and can be separated from biogas in the liquid or solid form, while methane remains in the gas phase. There are many options for the adjustment of temperature and pressure in order to perform the separation. Cryogenic separation can also be combined with other gas treatment methods. The advantage of the cryogenic separation is high methane purity with low losses. A disadvantage of cryogenic treatment is the energy required for refrigeration.

Biomethane is an attractive fuel, available now for support of the transition from the conventional fuels to sustainable low-emission mobility (advanced biofuels, e-fuels, hydrogen, etc.). The use of biomethane is connected with very low GHG emissions if produced through biomass gasification or even with negative GHG emissions when produced from substrates such as organic municipal wastes or manure (otherwise emitting methane during its decomposition process).

The potential for development is huge when looking only on biogas sector: in Germany less than 2% of biogas units (around 190 units) are biomethane production plants; in France it is less than 3% (around 30 units), while in other EU countries, this rate varies between 4% and

In Sweden and Germany, biomethane markets are well established so they can serve as good examples for analyzing pros and cons of solutions and models implemented by them. Automotive Industry Institute (PIMOT) together with national stakeholders and international partners (e.g., Swedish-Polish Sustainable Energy Platform) is involved in promotion and

*The Wobbe index* (W) used as an indicator for the assessment of gas utilization properties—

is a determinant of gas "calorific value"; it is the quotient of the Qc gas

The change in Wobbe's number may affect the power and operation

and square root of the relative density d.

12%. Only in Sweden 21% of biogas plants produce biomethane (62 units) [7].

*Biomethane* biogas upgraded to the quality of natural gas.

of the engine.

combustion heat in MJ/m<sup>3</sup>

The methane loss is between 1.5 and 2.5% [11].

development of biomethane market in Poland.

**4.5. Cryogenic separation**

**5. Conclusions**

**Nomenclature**

#### **4.2. Chemical absorption**

This technology is purifying biogas by absorption and chemical binding of carbon dioxide in aqueous solutions of amines (most often monoethanolamine (MEA) or dimethylethanolamine (DMEA)). Due to the high selectivity of the reaction of CO2 with amines, the process is more efficient than physical absorption. The gas obtained contains methane in an amount above 99% (even 99.4%), and methane losses can be limited to <0.1%. Raw biogas is pretreated with activated carbon to reduce the sulfur content (up to 0.5 ppm). In the case of increased H2 S content, an additional pretreatment plant is needed.

The process requires the use of heat, but does not require elevated pressure, so only the gas leaving the installation is compressed, which allows for a significant saving of energy. The amine solutions are regenerated by heating (110–160°C), and some of the heat is recovered.

#### **4.3. Membrane separation**

Biogas can be purified from both carbon dioxide and hydrogen sulfide with the application of a membrane technique. Membranes are typically combined in a tube bundle to provide maximum surface area. Typical operating pressures are 7 to 20 bar. The membrane acts selectively, i.e., only one component of the mixture passes through the filter freely, while the others are retained due to their size or affinity. Transport through membranes, as in the case of osmosis, occurs on the principle of difference of the potentials on both sides of the membrane. The difference of potentials stimulates the speed at which the particles pass through the membrane in order to compensate the concentration, pressure, or temperature.

Membrane separation is a relatively new technology for biogas purification and, within the last 10 years, has been significantly developed. The efficiency of one membrane is too low for biogas to achieve natural gas quality properties, so more than one membrane or additional purification technology should be used to achieve higher methane concentration. Moreover, in order to increase the separation efficiency, it is possible to recirculate the gas to be purified.

#### **4.4. Pressure swing adsorption (PSA)**

Pressure swing adsorption has been for years used in a gas industry, and recently it has been adapted for biogas upgrading. In this technology carbon dioxide is removed from biogas by adsorption on the surface-activated carbon, or on zeolite molecular sieves or carbon molecular sieves. CO2 molecules are smaller than methane molecules and thus CO2 accumulate on the surfaces or in the pores to a much greater degree than CH4 . The latter remains primarily in the gas phase. Adsorption is higher in higher pressures and in low temperatures. Biogas is cooled down to about 70°C and fed into the adsorption column. The biogas must be pre-purified in order to remove hydrogen sulfide and water vapor, which could, however, result in the deactivation of the active bed. The adsorption is a batch process and takes place in several columns. The methane loss is between 1.5 and 2.5% [11].

#### **4.5. Cryogenic separation**

The scrubbing technologies assume the regeneration of an aqueous solution (or organic) in the desorption column by depressurizing or passing the stream of air in a countercurrent

precipitating elemental sulfur causes operational problems of the installation. The scrubbing technologies in general do not require the supply of heat to the process and the use of chemicals, while they assume heat recovery and minimization of water consumption. Depending on the design of the column, the efficiency of upgrading with water scrubbing method is at

This technology is purifying biogas by absorption and chemical binding of carbon dioxide in aqueous solutions of amines (most often monoethanolamine (MEA) or dimethylethanolamine

efficient than physical absorption. The gas obtained contains methane in an amount above 99% (even 99.4%), and methane losses can be limited to <0.1%. Raw biogas is pretreated with activated carbon to reduce the sulfur content (up to 0.5 ppm). In the case of increased H2

The process requires the use of heat, but does not require elevated pressure, so only the gas leaving the installation is compressed, which allows for a significant saving of energy. The amine solutions are regenerated by heating (110–160°C), and some of the heat is recovered.

Biogas can be purified from both carbon dioxide and hydrogen sulfide with the application of a membrane technique. Membranes are typically combined in a tube bundle to provide maximum surface area. Typical operating pressures are 7 to 20 bar. The membrane acts selectively, i.e., only one component of the mixture passes through the filter freely, while the others are retained due to their size or affinity. Transport through membranes, as in the case of osmosis, occurs on the principle of difference of the potentials on both sides of the membrane. The difference of potentials stimulates the speed at which the particles pass through the membrane

Membrane separation is a relatively new technology for biogas purification and, within the last 10 years, has been significantly developed. The efficiency of one membrane is too low for biogas to achieve natural gas quality properties, so more than one membrane or additional purification technology should be used to achieve higher methane concentration. Moreover, in order to increase the separation efficiency, it is possible to recirculate the gas to be purified.

Pressure swing adsorption has been for years used in a gas industry, and recently it has been adapted for biogas upgrading. In this technology carbon dioxide is removed from biogas by adsorption on the surface-activated carbon, or on zeolite molecular sieves or carbon molecular

molecules are smaller than methane molecules and thus CO2

S, because the

S

with amines, the process is more

accumulate on the

. The latter remains primarily in the

(stripping). Passing the air stream is not recommended at higher levels of H2

the level of 90–99% of pure biomethane in the output gas [11].

(DMEA)). Due to the high selectivity of the reaction of CO2

in order to compensate the concentration, pressure, or temperature.

surfaces or in the pores to a much greater degree than CH4

content, an additional pretreatment plant is needed.

**4.2. Chemical absorption**

48 Biofuels - State of Development

**4.3. Membrane separation**

**4.4. Pressure swing adsorption (PSA)**

sieves. CO2

Cryogenic separation is a new biogas upgrading technology. The process takes place under conditions of very low temperatures (up to −100°C) and high pressures (40 bar). Carbon dioxide condenses or sublimes and can be separated from biogas in the liquid or solid form, while methane remains in the gas phase. There are many options for the adjustment of temperature and pressure in order to perform the separation. Cryogenic separation can also be combined with other gas treatment methods. The advantage of the cryogenic separation is high methane purity with low losses. A disadvantage of cryogenic treatment is the energy required for refrigeration.

#### **5. Conclusions**

Biomethane is an attractive fuel, available now for support of the transition from the conventional fuels to sustainable low-emission mobility (advanced biofuels, e-fuels, hydrogen, etc.).

The use of biomethane is connected with very low GHG emissions if produced through biomass gasification or even with negative GHG emissions when produced from substrates such as organic municipal wastes or manure (otherwise emitting methane during its decomposition process).

The potential for development is huge when looking only on biogas sector: in Germany less than 2% of biogas units (around 190 units) are biomethane production plants; in France it is less than 3% (around 30 units), while in other EU countries, this rate varies between 4% and 12%. Only in Sweden 21% of biogas plants produce biomethane (62 units) [7].

In Sweden and Germany, biomethane markets are well established so they can serve as good examples for analyzing pros and cons of solutions and models implemented by them. Automotive Industry Institute (PIMOT) together with national stakeholders and international partners (e.g., Swedish-Polish Sustainable Energy Platform) is involved in promotion and development of biomethane market in Poland.

#### **Nomenclature**

*Biomethane* biogas upgraded to the quality of natural gas.

*The Wobbe index* (W) used as an indicator for the assessment of gas utilization properties is a determinant of gas "calorific value"; it is the quotient of the Qc gas combustion heat in MJ/m<sup>3</sup> and square root of the relative density d. The change in Wobbe's number may affect the power and operation of the engine.

#### **Author details**

Magdalena Rogulska\*, Paweł Bukrejewski and Ewa Krasuska \*Address all correspondence to: m.rogulska@pimot.eu Automotive Industry Institute PIMOT, Warsaw, Poland

#### **References**

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**Author details**

50 Biofuels - State of Development

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Magdalena Rogulska\*, Paweł Bukrejewski and Ewa Krasuska

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[10] Bensmann M. Still growth in biomethane feed-in plants in 2016. Biogas Journal. English

[11] Biogas to Biomethane. German Biogas Association. Fachverband Biogas e. V. September

September 2014. http://www.iea-biogas.net/ [Accessed: 2018-01-20]

2017. http://www.biogas-to-biomethane.com [Accessed: 2018-01-15]

Issue. German Biogas Association. Autumn 2017. pp. 6-7

[4] Biogasmax 2006/2010 the synthesis. www.biogasmax.eu [Accessed: 2018-01-20]

\*Address all correspondence to: m.rogulska@pimot.eu Automotive Industry Institute PIMOT, Warsaw, Poland


[28] PN-EN 16723-2:2017. Natural gas and biomethane for use in transport and biomethane for injection in the natural gas network—Part 2: Automotive fuel specifications

**Section 3**

**Bioethanol**


**Section 3**
