*3.2.1 Production*

At present, Brazil and the United States (which holds 44% of world production and covered 1.2% of demand for automotive fuel producing 12 billion liters of ethanol) are the largest bioethanol producers of transport fuel worldwide (**Figure 2**), using cane and corn as feedstock, respectively. In Europe, bioethanol is mainly produced from sugar beet and wheat. Spain, Poland and France dominate the bioethanol sector in Europe with a total production of 500,000 tons in 2004. Sweden, Austria and Germany are also active in the production of bioethanol. Production in 2015, after continuing increases, amounted to 58 billion liters. The raw material for bioethanol production is common products from agricultural crops that grow using conventional cultivation techniques in different parts of Europe. Bioethanol production from agricultural crops can be a useful new market for regional economies and help regional development. Bioethanol is prepared by fermenting sugars, starch or cellulose using yeast [54]. The choice of feedstock depends on factors related to cost, technology and economics. Technologies for the production of bioethanol from agricultural products containing sugars and starch are commercially available [55].

Cellulosic materials such as agricultural and forest residues, as well as sorted household waste, are considered as future sources of raw material. However, these materials need to be hydrolyzed before fermentation, using a more complex process than the cereal equivalent. In the long run, cellulosic materials will be considered a potential source of sugars for ethanol production and their use can further reduce CO2 emissions.

Ethanol production is made from corn grain through two different processes: dry or wet milling. The main difference between the two is the grain processing method. In dry milling, which is the most common procedure, the dried grain is milled into a meal, which is then heated in water to liquefy the starch. Then introduce an enzyme to hydrolyze the starch into sugar, and then is added to ferment the sugar into ethanol and CO2 [56, 57]. The resulting CO2 can be used for the production of

**Figure 2***. Liquid bioethanol production in 2016 [45].*

carbonated beverages and dry ice and starch-off cereal residues can be marketed for animal feeding (DDGS). During wet milling, the plants, oil (germination) and protein content are separated from the starch (endosperm) in aqueous medium before starch hydrolysis and fermentation begin. With either dry or wet grinding, maize remains a low-cost source of starch that can easily be converted into sugar, fermented and distilled [58].

The choice of crops used as raw material for the production of bioethanol is closely linked to local climatological factors. About 60% of world bioethanol production is produced from sugar cane in the Central and South American countries, with Brazil on the leaf and the remaining 40% from other crops [59], with North America producing bioethanol almost exclusively from maize and the EU uses raw starch (cereals and maize) as well as crops such as sugar beet and sweets. The share of bioethanol in world biofuel production is over 94% with many countries replacing fossil fuels with biofuels [60, 61].

### *3.2.2 Environmental benefits*

The main advantage of bioethanol is that its use results in a significant reduction in greenhouse gas emissions. The use of 100% bioethanol results in a 50–60% reduction compared to conventional fuels. Benefits resulting from the use of blends are obviously smaller [47].

Regarding biodiesel, the benefits of climate change will depend on the raw material to be used to produce bioethanol. GHG (greenhouse gas) emission reductions of 50–60% arise if bioethanol is produced from sugar beet and wheat. If cellulosic materials are used, the net reduction may be greater – perhaps up to 75–80%. This is because less energy is needed for the cultivation of such plants, as well as the fact that during the production phase, energy efficient processes are also used, which also allow the use of renewable energy sources [47].

It is important to understand that bioethanol production is in itself an energyintensive process and requires significant amounts of energy produced from conventional fuels. However, it is clear that the use of bioethanol can help to achieve the objectives of legislation to prevent climate change. The use of bioethanol can also reduce emissions of other pollutants from vehicles, although this reduction depends on vehicle type and fuel specifications [55, 62].

#### *3.2.3 Disadvantages*

There are many concerns about energy crops and bioenergy due to the land and resources needed to produce biofuels. Bioethanol demand in the EU in 2010 amounted to 12.7 billion liters, with domestic production capacity of only 2 billion liters per year [63], so to meet demand it is estimated that it would be about 13% of the total arable land to be used for energy crops [64]. There are serious reactions to the increase in the price of maize and the change of use of limited resources such as cultivated land and water reserves. The use of lignocellulosic corn biomass is an alternative source of biofuels [65].

A major problem in biofuels is the high cost of energy you need to make biomass actively converted [49]. This problem can be solved by research in order to improve the biomass conversion technologies and how it is produced. An important step in the technological field in this direction is the development of second-generation bioethanol production technology from lignocellulosic raw materials, allowing even greater flexibility in the choice of raw materials, releasing much of the arable land from energy production [66].

**11**

*Maize as Energy Crop*

*DOI: http://dx.doi.org/10.5772/intechopen.88969*

initial estimate of 0.045%) [67, 68].

properties of the soil [69, 70].

removed from the domain.

by crop productivity [75].

**3.3 Biogas**

Finally, a great deal of concern is also given to the biofuels' performance ratio and more specifically to maize from the surveys that have been done to show that the energy efficiency index is positive and can reach 1.5 with more realistic consensus values is 1.25. The net solar conversion efficiency is very low 0.01% (below our

Although second generation bioethanol production technologies from lignocellulosic biomass are still growing, the contribution of maize biomass to bioenergy production is important. The advantage of maize biomass over other energy plants, such as *Miscanthus* x *giganteus*, *switchgrass* (*Panicum virgatum* L.) and others, is the fact that biomass occurs after harvesting the seed and does not require the use of a different area for its development. The main drawback of the use of maize biomass is the negative effects of removing crop residues on fertility and the physical

Corn ethanol is the third most efficient biofuel that yields 1350 l ethanol per hectare. The average US yield in maize is 8.6 mg grains/hectare. Assuming that 25 kilograms of corn grains produce about 10.6 liters of ethanol (a metric equivalent of 1 pounds yields US \$ 2.8), the average grain yield translates to 3650 liters/hectare. According to some estimates, the use of ethanol produced from corn cereals offers a 10–20% reduction in GHG emissions compared to petroleum fuels. Maize seed (stem, bark and pellet residues) has the potential to contribute substantially to the biofuel tank when appropriate conversion technologies are developed to convert cellulosic biomass to biofuels. Residues account for about 50% of the cultivation

Several issues need to be resolved before large-scale maize is used to produce biofuels, for example, biodegradation should be at a relatively close distance (about 80 km). From areas where the site will be harvested, transport costs are reduced. The "window" for harvesting the stover will be rather narrow in most places if not

However, in order for maize to have a sustainable outlook as an energy plant, it is important that the Net Energy Balance (NEB), in the overall production of biofuels from maize growing, be larger than the unit. The term NEB is defined as the fraction between outflows and inputs of the system. The input is considered to be the sum of the fossil fuels required throughout the biofuel production process and includes inputs during the installation and completion of the crop in the field (fertilizers, use of agricultural machinery, agrochemicals, etc.), transportation and the process of converting the seed or biomass into biofuels and as the output of the total energy of the biofuels produced that eventually end up outside the production system. The energy balance in the production of biofuels from maize is reported in the literature in many larger unit studies [72, 73] but also smaller. These differences in the results of the research are identified in the different biofuel production processes but mainly in environmental factors such as climatic and soil conditions, as well as in the cultivation practices followed and influenced the growth and production of maize cultivation [74] since NEB is mainly determined

Biogas production from energy crops is of increasing importance, as it offers

significant environmental benefits such as reducing CO2 emissions. In addition, it can contribute to raising farmers' incomes. Maize has great potential for biogas production. Biogas has the advantage that it can be used in many sectors, such as car fuel, but also as a source of energy in fixed units. Biogas has greater

biomass and are readily available in the maize production areas [71].

#### *Maize as Energy Crop DOI: http://dx.doi.org/10.5772/intechopen.88969*

*Maize - Production and Use*

fermented and distilled [58].

ing fossil fuels with biofuels [60, 61].

also allow the use of renewable energy sources [47].

depends on vehicle type and fuel specifications [55, 62].

*3.2.2 Environmental benefits*

are obviously smaller [47].

*3.2.3 Disadvantages*

alternative source of biofuels [65].

from energy production [66].

carbonated beverages and dry ice and starch-off cereal residues can be marketed for animal feeding (DDGS). During wet milling, the plants, oil (germination) and protein content are separated from the starch (endosperm) in aqueous medium before starch hydrolysis and fermentation begin. With either dry or wet grinding, maize remains a low-cost source of starch that can easily be converted into sugar,

The choice of crops used as raw material for the production of bioethanol is closely linked to local climatological factors. About 60% of world bioethanol production is produced from sugar cane in the Central and South American countries, with Brazil on the leaf and the remaining 40% from other crops [59], with North America producing bioethanol almost exclusively from maize and the EU uses raw starch (cereals and maize) as well as crops such as sugar beet and sweets. The share of bioethanol in world biofuel production is over 94% with many countries replac-

The main advantage of bioethanol is that its use results in a significant reduction in greenhouse gas emissions. The use of 100% bioethanol results in a 50–60% reduction compared to conventional fuels. Benefits resulting from the use of blends

Regarding biodiesel, the benefits of climate change will depend on the raw material to be used to produce bioethanol. GHG (greenhouse gas) emission reductions of 50–60% arise if bioethanol is produced from sugar beet and wheat. If cellulosic materials are used, the net reduction may be greater – perhaps up to 75–80%. This is because less energy is needed for the cultivation of such plants, as well as the fact that during the production phase, energy efficient processes are also used, which

It is important to understand that bioethanol production is in itself an energy-

conventional fuels. However, it is clear that the use of bioethanol can help to achieve the objectives of legislation to prevent climate change. The use of bioethanol can also reduce emissions of other pollutants from vehicles, although this reduction

There are many concerns about energy crops and bioenergy due to the land and resources needed to produce biofuels. Bioethanol demand in the EU in 2010 amounted to 12.7 billion liters, with domestic production capacity of only 2 billion liters per year [63], so to meet demand it is estimated that it would be about 13% of the total arable land to be used for energy crops [64]. There are serious reactions to the increase in the price of maize and the change of use of limited resources such as cultivated land and water reserves. The use of lignocellulosic corn biomass is an

A major problem in biofuels is the high cost of energy you need to make biomass actively converted [49]. This problem can be solved by research in order to improve the biomass conversion technologies and how it is produced. An important step in the technological field in this direction is the development of second-generation bioethanol production technology from lignocellulosic raw materials, allowing even greater flexibility in the choice of raw materials, releasing much of the arable land

intensive process and requires significant amounts of energy produced from

**10**

Finally, a great deal of concern is also given to the biofuels' performance ratio and more specifically to maize from the surveys that have been done to show that the energy efficiency index is positive and can reach 1.5 with more realistic consensus values is 1.25. The net solar conversion efficiency is very low 0.01% (below our initial estimate of 0.045%) [67, 68].

Although second generation bioethanol production technologies from lignocellulosic biomass are still growing, the contribution of maize biomass to bioenergy production is important. The advantage of maize biomass over other energy plants, such as *Miscanthus* x *giganteus*, *switchgrass* (*Panicum virgatum* L.) and others, is the fact that biomass occurs after harvesting the seed and does not require the use of a different area for its development. The main drawback of the use of maize biomass is the negative effects of removing crop residues on fertility and the physical properties of the soil [69, 70].

Corn ethanol is the third most efficient biofuel that yields 1350 l ethanol per hectare. The average US yield in maize is 8.6 mg grains/hectare. Assuming that 25 kilograms of corn grains produce about 10.6 liters of ethanol (a metric equivalent of 1 pounds yields US \$ 2.8), the average grain yield translates to 3650 liters/hectare. According to some estimates, the use of ethanol produced from corn cereals offers a 10–20% reduction in GHG emissions compared to petroleum fuels. Maize seed (stem, bark and pellet residues) has the potential to contribute substantially to the biofuel tank when appropriate conversion technologies are developed to convert cellulosic biomass to biofuels. Residues account for about 50% of the cultivation biomass and are readily available in the maize production areas [71].

Several issues need to be resolved before large-scale maize is used to produce biofuels, for example, biodegradation should be at a relatively close distance (about 80 km). From areas where the site will be harvested, transport costs are reduced. The "window" for harvesting the stover will be rather narrow in most places if not removed from the domain.

However, in order for maize to have a sustainable outlook as an energy plant, it is important that the Net Energy Balance (NEB), in the overall production of biofuels from maize growing, be larger than the unit. The term NEB is defined as the fraction between outflows and inputs of the system. The input is considered to be the sum of the fossil fuels required throughout the biofuel production process and includes inputs during the installation and completion of the crop in the field (fertilizers, use of agricultural machinery, agrochemicals, etc.), transportation and the process of converting the seed or biomass into biofuels and as the output of the total energy of the biofuels produced that eventually end up outside the production system. The energy balance in the production of biofuels from maize is reported in the literature in many larger unit studies [72, 73] but also smaller. These differences in the results of the research are identified in the different biofuel production processes but mainly in environmental factors such as climatic and soil conditions, as well as in the cultivation practices followed and influenced the growth and production of maize cultivation [74] since NEB is mainly determined by crop productivity [75].

#### **3.3 Biogas**

Biogas production from energy crops is of increasing importance, as it offers significant environmental benefits such as reducing CO2 emissions. In addition, it can contribute to raising farmers' incomes. Maize has great potential for biogas production. Biogas has the advantage that it can be used in many sectors, such as car fuel, but also as a source of energy in fixed units. Biogas has greater

#### *Maize - Production and Use*


#### **Table 3.**

*Biogas production globally from 2000 to 2016 [45].*

**Figure 3.** *Biogas production in continents in 2016 [45].*

advantages over other biofuels, such as bioethanol for the greater energy that produces, for example, a hectare of corn when converted to bioethanol, giving 20 Gj (Giga Joules). Biogas in the same area gives us nearly three times as much as 55 Gj. Maize, energy beet, rye and grass are crops grown commonly in the central, south-eastern Europe and United Kingdom for energy purposes and mainly for biogas production [74].

Silage maize is digested anaerobically, a conversion process where organic matter of biomass is converted into methane in four phases by bacteria in the absence of oxygen. The end products of the digestion process are biogas and digestate [76, 77].

A major problem we face with maize is its lignocellulos structure which prevents the process of fermenting. Several technologies have begun solving this problem, making maize commercially viable [78, 79]. To help increase the fermentation rate, we cut maize much shorter than a standard loader to increase the surface, which means it will be more accessible to microbes [80].

Recently, lignocellulosic materials have gained more interest as potential candidates for biogas production, but a large-scale implementation has not been widely adopted, mainly because of the complicated structure of the cell walls of lignocellulosic plants, which makes them resistant to hydrolysis by microbial attack. Therefore, the pretreatment of lignocellulosic material is essential step to achieve high process yields [81] (**Table 3**) (**Figure 3**).

### **4. Conclusions**

The rapid development of technology and the constant increase in the number of the world's population combined with the pollution of the environment lead to

**13**

*Maize as Energy Crop*

economical ways.

**Author details**

Elpiniki Skoufogianni1

and Nicholaos Danalatos1†

\* †

University of Thessaly, Volos, Greece

† These authors contributed equally.

provided the original work is properly cited.

Organization "DEMETER", Athens, Greece

\*Address all correspondence to: eskoufog@uth.gr

, Alexandra Solomou2†

1 Department of Agriculture, Crop Production and Rural Environment,

2 Institute of Mediterranean and Forest Ecosystems, Hellenic Agricultural

© 2019 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,

, Georgios Charvalas1†

**Conflict of interest**

*DOI: http://dx.doi.org/10.5772/intechopen.88969*

The authors declare no conflict of interest.

the need to find new energy resources more friendly and efficient. Energy crops can provide a large amount of energy by exploiting unused agricultural pieces of land or degraded land without burdening environments compared to fossil fuels. Maize is one of the best representatives of energy crops and presents great prospects in the bioethanol sector. Despite the great prospects of energy crops, and in particular maize, we still need research into more efficient use of biomass in cheaper and more
