**Use of Soybean Oil in Energy Generation**

Roberto Guimarães Pereira1, Oscar Edwin Piamba Tulcan2, Valdir de Jesus Lameira3, Dalni Malta do Espirito Santo Filho4 and Ednilton Tavares de Andrade5

*1Fluminense Federal University/TEM/PGMEC/MSG, Niterói, RJ 2National University of Colombia, Bogota 3INESC, Coimbra 4LAFLU/DIMEC/INMETRO, RJ 5Fluminense Federal University/TER/PGMEC 1,4,5Brazil 2Colombia 3Portugal* 

### **1. Introduction**

300 Recent Trends for Enhancing the Diversity and Quality of Soybean Products

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This chapter deals with the possibility of using soybean oil in energy generation. The environmental, energetic and social-economic aspects are discussed. The steps for obtaining biodiesel from soybean oil are presented as well as the characterization of soybean oil and soybean biodiesel. Results for performance and emissions of using soybean oil and soybean biodiesel in a stationary engine are also presented.

Vegetable oils are obtained predominantly from grains of different plant species. The oil extraction can be made by physical process (pressing) or chemical (solvent). The solvent extraction produces better results, but the more traditional way is physical extraction, which uses mechanical and hydraulic presses to crush the grains. A mixed extraction (mechanical/solvent) can also be done. Selecting the type of extraction depends on two factors: the productive capacity and oil content.

Soybean (*Glycine max* (L.) Merrill) is a very versatile grain that gives rise to products widely used by agro-chemical industry and food industry. Besides is a raw material for extraction of oil for biofuel production. Soybean has about 25% of oil content in grain.

In the agribusiness world, soybean production is, among the economic activities in recent decades, the most prominent. This can be attributed to several factors, such as structuring of a large international market related to trade in products of soybean, oilseed consolidation as an important source of vegetable protein and increased development and delivery of technologies that made possible the expansion of soy exploration for various regions of the world. The largest producers of soybeans are: United States, Brazil, Argentina, China and India.

One possible use of vegetable oil is in the power generation engines. The vegetable oil can be used directly in diesel engines, preferably mixed with diesel. It may also undergo a chemical reaction (transesterification), yielding biodiesel and glycerol. In literature, several works are related to the use of vegetable oil and biodiesel for power generation, as evidenced below.

Use of Soybean Oil in Energy Generation 303

Inedible vegetable oils and their derivatives can, also, be used as alternative diesel fuels in

The advantages of using vegetable oil as fuel are evidenced in the literature (Alonso et al.

One of the main advantages of vegetable oils is its life cycle, as it is a closed cycle. Crops take CO2 via photosynthesis from the atmosphere. Oil is extracted from these crops which can be used directly as fuel or, after the pertinent transformations, a fuel can be obtained

Environmental advantages of vegetable oils are: minor influence on the greenhouse effect when used instead of fossil fuels; biodegradability; lower sulfur and aromatic content; at lower percentages of vegetable oil blends with diesel have shown better results than the

Energetic advantages of vegetable oils are: renewable energy source; reduction of the dependence on fossil fuels; positive energy balance; the fuel production technology is simple and proven; heating values of various vegetable oils are nearly 90% to those of diesel fuel; higher flash point allows it to be stored at high temperatures without any fire hazard;

Social-economic advantages of vegetable oils are: use of marginal land for energy purposes; maintains employment and income levels in rural areas; avoids population migrations; encourages job creation in various agro-industries; contributes to the creation of new jobs; straight vegetable oils are available normally in rural area where its usage is advantageous especially in smaller engines in agricultural sector; improve the living conditions of the rural people and offer greater income opportunities through enhanced rural employment; plant leafs and cake can be used as organic manure which can be source of additional income farmers; selected crops can be grown on arid and semi-arid lands which are presently not

The main disadvantages of vegetable oils, compared to diesel fuel, are higher viscosity, lower volatility, and the reactivity of unsaturated hydrocarbon chains. The problems meet in long term engine use (Misra & Murthy, 2010). The land required for commercial production

Many countries have potential to produce biodiesel from vegetable oil. The top 10 countries in terms of absolute potential are: Malaysia, Indonesia, Argentina, USA, Brazil, Netherlands,

Some reasons for sufficiently strengthen the program for the use of biofuels are: the variation in prices for oil, which in recent years has fluctuated between \$ 40 and 150 per barrel, the political and social pressure in order to reduce the emission of gases that cause global warming, the development of the market for carbon credits, the need to strengthen the agriculture industry and the possibility of strengthening the energy matrix, reducing dependence on foreign energy sources and giving relief to the trade balance with clear

The possibility to produce hydrocarbons from different raw material to replace the diesel makes the definition of biodiesel a complex and legal nature. Many documents of an academic nature define biodiesel as a monoalkyl ester of vegetable oil or animal fat, but official documents and international standards are more specific, defining the process by which one can obtain the ester and the characteristics that it must have to be considered

additional oxygen molecule in its chemical structure helps in combustion process.

which, when burned, generates CO2 that can be absorbed by the plants.

fossil diesel in terms of engine performance and exhaust emissions.

cultivable; having carbon credit value (Kyoto protocol).

effects on the macroeconomics of the country.

Germany, Philippines, Belgium and Span (Sharma & Singh, 2009).

is vast.

biodiesel.

compression ignition engines (No, 2011).

2008; Misra & Murthy, 2010) as described below.

A review of the use of vegetable oils as fuel in compression ignition (CI) engines is presented (Hossain & Davies, 2010). The review shows that a number of plant oils can be used satisfactorily in CI engines, without transesterification, by preheating the oil and/or modifying the engine parameters. As regards life-cycle energy and greenhouse gas emission analyses, these reveal considerable advantages of raw plant oils over fossil diesel and biodiesel.

It is pointed out (Grau et al., 2010) that straight vegetable oil can be used directly in diesel engines with minor modifications. It is proposed a small-scale production system for selfsupply in agricultural machinery.

It is emphasized (Misra & Murthy, 2010) that the ever increasing fossil fuel usage and cost, environmental concern has forced the world to look for alternatives. Straight vegetable oils in compression ignition engine are a ready solution available, however, with certain limitations and with some advantages.

It is presented (Sidibé et al., 2010) a literature review on the use of crude filtered vegetable oil as a fuel in diesel engines. It is emphasized the potential and merits of this renewable fuel. Typically, straight vegetable oils produced locally on a small scale, have proven to be easy to produce with very little environmental impact. However, as their physico-chemical characteristics differ from those of diesel oil, their use in diesel engines can lead to a certain number of technical problems over time.

A review on the utilization of used cooking oil biodiesel is presented (Enweremadu & Rutto, 2010). There were no noticeable differences between used cooking oil biodiesel and fresh oil biodiesel as their engine performances, combustion and emissions characteristics bear a close resemblance.

A review on biodiesel production, combustion, emissions and performance is shown (Basha et al., 2009). A vast majority of the scientists reported that short-term engine tests using vegetable oils as fuels were very promising, but the long-term test results showed higher carbon built up, and lubricating oil contamination, resulting in engine failure. It was reported that the combustion characteristics of biodiesel are similar as diesel. The engine power output was found to be equivalent to that of diesel fuel.

An overview of political, economic and environmental impacts of biofuels is presented (Demirbas, 2009a). Biofuels provide the prospect of new economic opportunities for people in rural areas in oil importer and developing countries. Renewable energy sources that use indigenous resources have the potential to provide energy services with zero or almost zero emissions of both air pollutants and greenhouse gases. Biofuels are expected to reduce dependence on imported petroleum with associated political and economic vulnerability, reduce greenhouse gas emissions and other pollutants, and revitalize the economy by increasing demand and prices for agricultural products.

It is emphasized (Sharma & Singh, 2009) that Biodiesel, a renewable source of energy seems to be an ideal solution for global energy demands.

The soy, which cultivation is widespread in the world, can be used to produce vegetable oil in order to be used as fuel, according some following examples.

It is pointed out (Liu et al., 2008) that Soybean (*Glycine max* (L.) Merrill), one of the most important crops in China, has been known to man for over 5000 years. The largest production areas in China are in the Northeast China's three provinces, where soybean is spring seeded and grown as a full-season crop.

A study about large-scale bioenergy production from soybeans in Argentina is presented (van Dam et al., 2009), showing the potential and economic feasibility for national and international markets.

A review of the use of vegetable oils as fuel in compression ignition (CI) engines is presented (Hossain & Davies, 2010). The review shows that a number of plant oils can be used satisfactorily in CI engines, without transesterification, by preheating the oil and/or modifying the engine parameters. As regards life-cycle energy and greenhouse gas emission analyses, these reveal considerable advantages of raw plant oils over fossil diesel and

It is pointed out (Grau et al., 2010) that straight vegetable oil can be used directly in diesel engines with minor modifications. It is proposed a small-scale production system for self-

It is emphasized (Misra & Murthy, 2010) that the ever increasing fossil fuel usage and cost, environmental concern has forced the world to look for alternatives. Straight vegetable oils in compression ignition engine are a ready solution available, however, with certain

It is presented (Sidibé et al., 2010) a literature review on the use of crude filtered vegetable oil as a fuel in diesel engines. It is emphasized the potential and merits of this renewable fuel. Typically, straight vegetable oils produced locally on a small scale, have proven to be easy to produce with very little environmental impact. However, as their physico-chemical characteristics differ from those of diesel oil, their use in diesel engines can lead to a certain

A review on the utilization of used cooking oil biodiesel is presented (Enweremadu & Rutto, 2010). There were no noticeable differences between used cooking oil biodiesel and fresh oil biodiesel as their engine performances, combustion and emissions characteristics bear a

A review on biodiesel production, combustion, emissions and performance is shown (Basha et al., 2009). A vast majority of the scientists reported that short-term engine tests using vegetable oils as fuels were very promising, but the long-term test results showed higher carbon built up, and lubricating oil contamination, resulting in engine failure. It was reported that the combustion characteristics of biodiesel are similar as diesel. The engine

An overview of political, economic and environmental impacts of biofuels is presented (Demirbas, 2009a). Biofuels provide the prospect of new economic opportunities for people in rural areas in oil importer and developing countries. Renewable energy sources that use indigenous resources have the potential to provide energy services with zero or almost zero emissions of both air pollutants and greenhouse gases. Biofuels are expected to reduce dependence on imported petroleum with associated political and economic vulnerability, reduce greenhouse gas emissions and other pollutants, and revitalize the economy by

It is emphasized (Sharma & Singh, 2009) that Biodiesel, a renewable source of energy seems

The soy, which cultivation is widespread in the world, can be used to produce vegetable oil

It is pointed out (Liu et al., 2008) that Soybean (*Glycine max* (L.) Merrill), one of the most important crops in China, has been known to man for over 5000 years. The largest production areas in China are in the Northeast China's three provinces, where soybean is

A study about large-scale bioenergy production from soybeans in Argentina is presented (van Dam et al., 2009), showing the potential and economic feasibility for national and

biodiesel.

supply in agricultural machinery.

limitations and with some advantages.

number of technical problems over time.

power output was found to be equivalent to that of diesel fuel.

increasing demand and prices for agricultural products.

in order to be used as fuel, according some following examples.

to be an ideal solution for global energy demands.

spring seeded and grown as a full-season crop.

international markets.

close resemblance.

Inedible vegetable oils and their derivatives can, also, be used as alternative diesel fuels in compression ignition engines (No, 2011).

The advantages of using vegetable oil as fuel are evidenced in the literature (Alonso et al. 2008; Misra & Murthy, 2010) as described below.

One of the main advantages of vegetable oils is its life cycle, as it is a closed cycle. Crops take CO2 via photosynthesis from the atmosphere. Oil is extracted from these crops which can be used directly as fuel or, after the pertinent transformations, a fuel can be obtained which, when burned, generates CO2 that can be absorbed by the plants.

Environmental advantages of vegetable oils are: minor influence on the greenhouse effect when used instead of fossil fuels; biodegradability; lower sulfur and aromatic content; at lower percentages of vegetable oil blends with diesel have shown better results than the fossil diesel in terms of engine performance and exhaust emissions.

Energetic advantages of vegetable oils are: renewable energy source; reduction of the dependence on fossil fuels; positive energy balance; the fuel production technology is simple and proven; heating values of various vegetable oils are nearly 90% to those of diesel fuel; higher flash point allows it to be stored at high temperatures without any fire hazard; additional oxygen molecule in its chemical structure helps in combustion process.

Social-economic advantages of vegetable oils are: use of marginal land for energy purposes; maintains employment and income levels in rural areas; avoids population migrations; encourages job creation in various agro-industries; contributes to the creation of new jobs; straight vegetable oils are available normally in rural area where its usage is advantageous especially in smaller engines in agricultural sector; improve the living conditions of the rural people and offer greater income opportunities through enhanced rural employment; plant leafs and cake can be used as organic manure which can be source of additional income farmers; selected crops can be grown on arid and semi-arid lands which are presently not cultivable; having carbon credit value (Kyoto protocol).

The main disadvantages of vegetable oils, compared to diesel fuel, are higher viscosity, lower volatility, and the reactivity of unsaturated hydrocarbon chains. The problems meet in long term engine use (Misra & Murthy, 2010). The land required for commercial production is vast.

Many countries have potential to produce biodiesel from vegetable oil. The top 10 countries in terms of absolute potential are: Malaysia, Indonesia, Argentina, USA, Brazil, Netherlands, Germany, Philippines, Belgium and Span (Sharma & Singh, 2009).

Some reasons for sufficiently strengthen the program for the use of biofuels are: the variation in prices for oil, which in recent years has fluctuated between \$ 40 and 150 per barrel, the political and social pressure in order to reduce the emission of gases that cause global warming, the development of the market for carbon credits, the need to strengthen the agriculture industry and the possibility of strengthening the energy matrix, reducing dependence on foreign energy sources and giving relief to the trade balance with clear effects on the macroeconomics of the country.

The possibility to produce hydrocarbons from different raw material to replace the diesel makes the definition of biodiesel a complex and legal nature. Many documents of an academic nature define biodiesel as a monoalkyl ester of vegetable oil or animal fat, but official documents and international standards are more specific, defining the process by which one can obtain the ester and the characteristics that it must have to be considered biodiesel.

Use of Soybean Oil in Energy Generation 305

Biodiesel is known as monoalkyl, such as methyl and ethyl, esters of fatty acids. Biodiesel can be produced from a number of sources, including recycled waste vegetable oil, oil crops and algae oil. Biodiesels play an important role in meeting future fuel requirements in view of their nature (less toxic), and have an edge over conventional diesel as they are obtained

The transesterification process is used to transform triglycerides into esters, or biodiesel. In the process of transesterification, the triglycerides found in different kinds of oils and fats react with alcohol, usually methanol or ethanol to produce esters and glycerin. For the reaction to occur it is necessary to use a catalyst. Processes performed the supercritical conditions of methanol transesterification can be conducted without the catalyst. (Demirbas,

In the transesterification process, a triglyceride molecule reacts with an alcohol molecule causing the separation of one of the fatty acids of the triglyceride, producing a diglyceride and an ester. This diglyceride reacts with a second molecule of alcohol that takes another fatty acid, forming a second ester and a monoglyceride. Finally a third molecule of alcohol reacts with the monoglyceride, forming the third ester and a molecule of glycerin. The reactions occurring are reversible, and the stoichiometric ratio is three moles of alcohol for each mole of oil being processed. The reaction can be carried out with concentrations of alcohol in excess, as this reduces time and increases the conversion efficiency of the process.

The transesterification process using methanol and base catalyst is the most commonly used to produce biodiesel. The catalysts commonly used are sodium hydroxide (NaOH) or potassium hydroxide (KOH). The catalyst is diluted in alcohol and then added the oil. The product is the ester (biodiesel) and crude glycerin. The glycerin is separated from the ester

Repeated washing processes are performed by adding acidified water in the reaction products. This mixture is stirred lightly and serves to remove residual glycerine soap, catalyst and serves as a neutralizing agent of the fuel. The washing process is repeated until the biodiesel becomes clear. The main drawbacks of the process are the presence of water on some of the reagents and the high level of free fatty acids in the raw material. In both cases,

The transesterification process can also be developed using acid catalysts and no homogeneous catalysts. In the case of acid catalysts, the process times are longer, but do not have drawbacks with the water content and free fatty acids. In the case of no homogeneous catalysts, these bring benefits in: reducing the washing process; product separation and

Methanol and ethanol are produced on an industrial scale and their use in transesterification

The biodiesel used in several countries of Europe and in the United States is a mixture of methyl esters. Methanol is usually obtained from non-renewable fossil fuels, but can also be obtained by distillation of wood; this route, however, produces smaller quantities. The technology of biodiesel production using methanol is fully understood, however, this route

The transesterification using ethanol is more difficult because the use of alcohol, even if anhydrous, involves problems in the separation of glycerin from the reaction medium. However, the use of ethanol is advantageous, since it is produced on a large scale in

the transesterification reaction is replaced by a saponification reaction.

has the disadvantage that methanol is extremely toxic.

from renewable sources (Demirbas, 2009b).

2003; Saka & Kusdiana, 2001)

by decanting or centrifuging.

(Lang et al., 2001)

reuse of catalysts.

reactions has been reported.

The regulations for biodiesel have been developed in different countries where its use is permitted. In the U.S. the standard for biodiesel is set by the technical standard ASTM D 6751, the European Union is related with the standard EN 14214 and in Brazil is set in the ANP (National Petroleum Agency) No. 07 from 19.03.2008.

Biodiesel can be produced from different oilseeds, according to the design of the plant, market conditions and availability of raw material in the region. Each oilseed production has a different culture method and a different destination. The disposal of oils for biodiesel production must take into account beyond the capacity of oil production, market competitiveness in relation to the cost of oil and the price of a barrel of fuel. Biodiesel can be obtained, too, from used cooking oil, animal fats and algae.

Just as vegetable oil, the use of biodiesel as fuel in partial or total replacement to diesel has many advantages that have been highlighted in the literature (Demirbas, 2009b; Pereira et al., 2007).

Environmental advantages of biodiesel are: greenhouse gas reductions; biodegradability; higher combustion efficiency; improved land and water use; carbon sequestration; lower sulfur content; lower aromatic content; less toxicity.

Energetic advantages of biodiesel are: supply reliability; higher flash point; reducing use of fossil fuels; ready availability; renewability.

Social-economic advantages of biodiesel are: sustainability; fuel diversity; increased number of rural manufacturing jobs; increased income taxes; increased investments in plant and equipment; agricultural development; international competitiveness; reducing the dependency on imported petroleum.
