9.1 Global production of Jatropha

Jatropha is a shrub, belonging to the Euphorbiaceae family, thriving in various environments and across a wide range of ecosystems. It is a plant that can survive several months with minimal water and can actually live up to 40 years or more. It is not edible to human beings or animals. The jatropha industry is in its very early stages, covering a global area estimated at some 900,000 ha. More than 85 percent of jatropha plantings are in Asia, chiefly Myanmar, India, China and Indonesia. Africa accounts for around 12 percent or approximately 120,000 ha, mostly in Madagascar and Zambia, but also in Tanzania and Mozambique. The West African nations of Mali, Ghana and Senegal have also established lofty production targets for Jatropha notably; to cultivate 320,000 ha of Jatropha curcas in Senegal by 2012 and 1 million ha in Ghana in the medium term (OECD, 2008). Latin America has approximately 20,000 ha of jatropha, mostly in Brazil. The area planted with jatropha was projected to grow to 4.72 million ha by 2010 and 12.8 million ha by 2015. By then, Indonesia is expected to be the largest producer in Asia with 5.2 million ha, Ghana and Madagascar together will have the largest area in Africa with 1.1 million ha, and Brazil is projected to be the largest producer in Latin America with 1.3 million ha. Total biogas generation potential from Jatropha curcas cakes in India has been estimated as 2,550 million m3 from 10.2 lakh metric ton of J. curcas oil seed cakes.

Jatropha curcas contains about 30% oil leaving behind presscake (75% including about 5% losses of oil in extraction process in the mechanical expeller) with residual oil. The oil is used for preparing bio-diesel (Achten et al., 2008) and in soap preparation. The press cake is rich in organic matter (Abreu, 2009). It can be used as manure, as feedstock for biogas production, animal feed and so forth. (Agarwal, 2007). Also, Jatropha oil cake is used for enriching the soil (Reyadh, 1997). Envis (2004) observed that Jatropha oil cake is an organic fertilizer that is superior to cattle manure and it is in great demand by farmers.

There is a great challenge for the management of waste, especially in generating clean energy that will decrease the burden of environmental pollution, with the fields of both science and technology working in unison to develop new ways of utilizing and extending it’s shelf-life by developing alternative uses. Until now, there have been a lot of publications dealing with solid waste management, but there are still very few documents that can provide information regarding the use of this waste as a raw material. In the last few years, research has been focused on the transformation of waste into a useful product has made considerable progress. In developing countries, due to imbalance of demand and supply of energy, mainly in rural areas, choosing a source that fulfills the requirements has become essential, and they can use waste as other raw materials. Biogas, which is mainly generated from organic waste, is useful for them. In this context, a book on "Biogas", in which the emphasis is made on the chemistry of each step involved in biogas generation along with engineering principles and practices, is introduced. Each chapter of the book carries valuable and updated information from basics to apex, helping readers to understand more precisely. Different concepts have been covered to expand the views of the readers about the subject.

This publication will be very helpful to academics, researchers, NGOs and others working in the field.

Dr. Sunil Kumar

National Environmental Engineering Research Institute (NEERI), Kolkata Zonal Laboratory I-8, Kolkata,

India

As mentioned above, the economic prosperity and quality of life of a country are closely linked to the level of its per capita energy consumption and the strategy adopted to use energy as a fundamental tool to achieve the same (Amigun et al. 2008; Singh & Sooch 2004). This is illustrated in Figure 1.

Renewable energy could provide the much desired sustainable rural revitalization in most developing countries. It is an ideal alternative because it could be a less expensive option for low income communities. An ideal renewable energy source is one which is locally available, affordable and can be easily used and managed by local communities. Anaerobic digestion is one of a number of technologies that offers the technical possibility of decentralized approaches to the provision of modern energy services using resources such as; cow dung, human waste and agricultural residues to produce energy. Anaerobic digestion of the large quantities of municipal, industrial and agricultural solid waste in Africa can provide biogas that can be used for heat and electricity production and the digester residue can be recycled to agriculture as a secondary fertilizer. Anaerobic digestion systems are relatively simple, economical, and can operate from small to large scales in urban and rural locations (Amigun & von Blottnitz, 2009). In this regard, many African governments have realised that renewable energies could play a very important role in supplementing other existing energy sources.

Anaerobic digestion describes the natural breakdown of organic matter in the absence of oxygen into a methane rich gas (biogas) via the complex and synergistic interactions of various micro-organisms types including hydrolytic, fermentative, acidogenic, and methanogenic bacteria (Lusk et al. 1996, Parawira, 2004b). The first group of microorganism secretes enzymes, which hydrolyses polymeric materials such as proteins and polysaccharides to monomers such as glucose and amino acids. The fermentative bacteria convert these monomers to organic acids, primarily propionic and acetic acid. The acidogenic bacteria convert these acids to hydrogen, carbon dioxide, and acetate, which the methanogens utilize via two major pathways to produce methane and carbon dioxide (Lusk et al. 1996; Verma 2002). The potential for organic matter decomposition to generate a flammable gas has been recognized for more than 400 years. In 1808, it was determined that methane was present in the gases produced during the anaerobic digestion of cattle manure. In 1868, Bechamp, a student of Pasteur attempted to isolate the microorganism responsible for the anaerobic bioconversion of ethanol to methane.

The first practical application of anaerobic digestion for energy production took place in England in 1896 when biogas from sewage sludge digestion was used to fuel street lamps. As is the case for many other renewable technologies, interests in anaerobic digestion suffered with the rise of the dependence of petroleum. However some developing countries, mainly in Asia, embraced the technology for the small scale provision of energy and sanitation services (Monnet 2003). Since that time, anaerobic digestion has received considerable interest to harness its waste disposal and energy producing capabilities, with municipal sewage disposal attracting the widest application (Lusk et al. 1996).

The anaerobic digestion process will occur at most temperatures below 70°C, but in the commercial operation of digesters two main temperature ranges are typically employed; the mesophilic range (30-44°C ) and thermophilic range (45-60°C). In addition to sewage sludge, organic farm wastes, municipal solid waste, green botanical waste and organic industrial waste have also been used as feedstock in various small to large scale digesters across the world. Current commercial anaerobic digestion processes generally involve the following steps; pre-treatment (including size reduction and the separation of non-biodegradable substances), digestion, biogas cleaning and conditioning (to remove CO2, water vapour and other undesirables), and subsequently biogas utilization (via internal combustion engines, or the more efficient combined heat and power plant (CHP)). The solid residue from the digestion process (called digestate) can be used as compost.

Various types of small to medium scale biogas digesters have been developed including the floating drum, fixed dome, and plastic bag design (Amigun & Blottnitz 2007). The amount of biogas produced from a specific digester depends on factors such as the amount of material fed, the type of material, the carbon/nitrogen ratio, and digestion time and temperature (Omer & Fadalla 2003; Schwart et al. 2005; Chynoweth et al. 2001). Depending on the context, any type may be used. However, most of the small to medium scale biogas plants built so far are of the fixed dome type (Amigun & von Blottnitz 2009). The technology is gradually gaining popularity in developing countries, especially in Africa where the lack of clean and sustainable energy source represents damage to the environment and its people (Amigun & von Blottnitz 2009). In addition, Sub-Saharan Africa with its warm climates is well-suited for the biogas digester technology (Aboyade 2004).

In the subsequent sections of this chapter, the current state of status of biogas technology in sub-Saharan Africa will be presented, along with a discussion of opportunities and challenges faced. The socio-economic benefits of biogas digesters is also been investigated through the use of case studies of commercial and demonstration plants on the continent. The economics of biogas technology in terms of investment and maintenance in the rural African context is discussed.

The amount of gas produced depends on the slurry in the digester volume (Fulford, 1988). The digester volume is also related to the retention time measured in days and the loading rate, in terms of manure solids per unit liquid volume (San Thy et al., 2003). According to experiences in China, 97% of the total yield of gas from fermenting cattle manure will be produced in a period of 50 days at 350C. The hydraulic retention time (HTR) in anaerobic digesters is determined by calculating the number of days required for displacement of the fluid volume of the culture. At a given organic loading rate, the HTR is lower when using high water — content feeds than when using those containing less water (Fannin and Biljetina, 1987). The detention time is dependent on all the factors discussed above. Generally a retention time of between 30 and 45 days and in some cases 60 days is enough for substantial gas production (Clanton et al., 1985; Carcelon and Clark, 2002). A study by Hill (1982) found that detention times for digesters designed to produce maximum daily methane volume varied from 7.9 days for dairy waste to 14.8 days for poultry, and similar wide variations in loading rates existed between the two wastes.

Ali et al., (2010), studied the use of Jatropha curcas defatted waste as an alternative feed in biogas plant for its bio-methanisation. The paper observed that as it remains as defatted cake after the extraction of non-edible oil from Jatropha seeds, it cannot be used directly for any purpose due to presence of toxic substance called ‘curcin’. This toxin renders it unsafe for the animal feed and other purposes. It contains 5.73% nitrogen, 1.5% phosphorus and about 1% potassium. On the basis of its chemical composition, its application as substrate to the biogas plant can be a sustainable alternative as compared to the other applications of Jatropha press cake. The study was conducted on a floating drum type biogas plant. The study observed that the biogas plant, initially charged with pure cattle dung, when gradually replaced with Jatropha oil cake (0 — 100%), increased the biogas production up to approximately 25% in reasonable time duration. A significant increase in the percentage of nitrogen, phosphorus and potassium during the biofermentation process invokes the use of the effluent slurry as organic manure. Simultaneous reduction in the amount of the oil (5.67 to 3.95%) sustains the possibility of degradation of oil during methanisation. The plant has showed higher biogas yields at low temperatures also. Therefore, Jatropha defatted waste can successfully be used as an addition as well as substrate in already running cattle dung based biogas plant to get higher yield of biogas in comparison to cattle dung feed.

A laboratory experiment was conducted to find out the biogas production potential of dried, powdered Jatropha cake mixed with buffalo dung at 6% total solids (Prateek, 2009). The experiment was run on daily feeding basis in 5-litre capacity glass digesters for 180 days, while biogas production was recorded at 24 hr interval. Quality of biogas and nutritive value of effluent slurry was also determined. Results show significantly higher (139.20%) biogas production in test (Jatropha cake + Buffalo dung) over control (Buffalo dung only) digesters with methane content of 71.74%. Nutritive value of effluent slurry of test digester was significantly higher in terms of available nitrogen and potassium; calcium; magnesium and carbonate contents than that of control digesters. This co-digestion resulted in 92.94% decrease in chemical oxygen demand.

Dhanya et al., (2009) researched the biogas production potential of Jatropha (Jatropha curcas, L) Fruit Coat (JFC) alone and in combination with cattle dung (CD) in various proportions at 15 per cent total solids by batch phase anaerobic digestion for a period of ten weeks HRT (Hydraulic Retention Time) under a temperature of 350C+10C. The maximum biogas production was noticed in cattle dung and Jatropha Fruit Coat in 2:1 ratio with 403.84 L/kg dry matter followed by 3:1,1:2, 1:1 and 1:3 having 329.66, 219.77, 217.79, 203.64 L/kg dry matter respectively as compared to 178.49 L/kg dry matter in CD alone. The JFC alone was found to produce 91% of total biogas of that obtained from cattle dung. The per cent methane content of the biogas in all the treatments was found on par with cattle dung.

Babajide A. Adelekan

Federal College of Agriculture Ibadan, Institute of Agricultural Research & Training, Ibadan,

Nigeria

1. Introduction

The chapter presents comprehensive and up-to-date knowledge on the themes of biogas, bioethanol, biodiesel as obtained from cassava, cocoyam, jatropha, grasses and manure. The author’s research findings as well as those reported by other researchers are used for the discussion. Recommendations as regards how to benefit much more from these biofuels derived from selected tropical crops are presented. It is anticipated that these recommendations will be of immense help to academics and industry specialists working in such areas.

None of the biological activities of anaerobic microorganisms, including their development, breeding and metabolism, requires oxygen. In fact, they are very sensitive to the presence of oxygen. The breakdown of organic materials in the presence of oxygen will produce carbon dioxide; in airless conditions, it produces methane (Buren, 1983; Voermans, 1985). Ferguson and Mah (1987) pointed out that methane-producing bacteria carry out the terminal step in the formation of biogas from the anaerobic decomposition of biomass. Methane is the final product of mineralizing the organic material in digesters and most anaerobic freshwater habitats. Most of the chemical energy in the starting materials (substrates) actually ends up in the methane released by these anaerobic bacteria. Ferguson and Mah (1987) noted further that in direct contrast, aerobic bacterial metabolism releases most of the chemical energy in the starting substrates by oxidizing them to carbon dioxide and water. Buren (1983) noted that if the digester is not sealed to ensure the absence of air. The action of the microorganisms and the production of biogas will be inhibited and some will escape. It is therefore crucial that the biogas digester be airtight and watertight.

Ways and means have been sought for many years to be able to produce oil-substitute fuel. Biodiesel extracted from fresh or used vegetable oil whether edible or not, is one such renewable alternative under consideration. Merits of biodiesel are that it can be directly used in engines with little or no modifications; contains little or no sulphur; no aromatics; has a higher cetane number and contains about 10% built-in oxygen and these properties help it burn fully with the result of having less carbon monoxide production, less unburnt carbon and less particulate matter residues. The production of biodiesel would be cheap as it could preferably be extracted from non edible oil sources. Jatropha curcas (Linaeus), a non­edible oil-bearing and drought-hardy shrub with ecological advantages, belonging to the Euphorbiaceae family, has been found to be the most appropriate renewable alternative source of biodiesel. Presently, the procedure for biodiesel production from jatropha seeds starts with harvesting whole ripe fruits. These fruits are then opened to remove the typically 3 or 4 seeds contained in each fruit. (A matured plant produces about 20kg of seeds in a year). These seeds are then sundried and afterwards stones, sticks, mouldy or damaged seeds and other foreign materials are handpicked from the batch of dried seeds. Next, this cleaned batch of seeds is crushed in an oil extraction machine to free the oil. This extracted oil is then filtered to remove impediments and the oil is poured in air-tight containers for storage. The extracted and filtered vegetable oil can be used directly as a fuel in suitable diesel engines without undergoing the trans-esterification process (Achten et al., 2008). However, to make it more useful in many engines, this Jatropha oil has to undergo a trans­esterification process of the triglyceride molecules in fats and oils with light weight alcohols like ethanol and methanol in a reactor in order to convert it to biodiesel. After being put into the reactor, the Jatropha oil settles; it is washed and purified by evaporation, and the liquid produced is biodiesel. Under optimal conditions, Jatropha curcas produces a higher oil yield per hectare compared to peanuts (Arachis hypogea), sunflower (Helianthus annus), soyabean (Glycine max), maize (Zea mays) and cotton (Gossypium species) (Kaushik et al., 2007). Biodiesel is a promising alternative because it is a renewable liquid fuel source that can be used alone and alternatively blended with petroleum-based diesel.

Jatropha’s potential as a new energy source comes at time when interest in biofuel production is at an all-time high. As observed by Parwira (2010), biofuel production could potentially position developing nations to become net exporters of fuel which could greatly advance their objectives of economic independence. The paper noted further that many

international corporations in Scandinavia, China, and Europe are purchasing tracts of land in developing countries (especially African countries) in an attempt to capitalize on this growth industry. New uses are being found for biofuel continually and this creates an impetus to strengthen efforts to produce them. In fact, several wireless communication companies have constructed cellular network base stations that are powered by Jatropha — based biofuel (Katembo and Gray, 2007). Presently, corn ethanol has a yield of 3100-4000 L/ha. This is still much higher than Jatropha curcas which is approximately 460-680 L/Ha of oil (Dar 2007). However, the production of Jatropha biodiesel is still very attractive largely due to its excellent fuel properties.

Kywe and Oo (2009) obtained a biodiesel yield of 30 gallons/day from a pilot plant which produced oil from Jatropha. The biodiesel demonstrated excellent fuel properties and it was found to be of very good quality. Tomomatsu and Swallow (2007) studied the economics and potential value of Jatropha curcas biodiesel production in Kenya and noted that in recent years, the production of Jatropha curcas has been widely promoted by private enterprises, non-governmental organizations and development agencies as one of the most viable candidates for biodiesel feedstock in Africa. While multiple benefits of jatropha production such as a petroleum product substitute, greenhouse gas mitigation and rural development are emphasized, the viability of production at farm level is questioned. The study revealed that the profitability of jatropha production for smallholder farmers is expected to be minimal unless farm-level production is accompanied by significant investments and policies targeted at enhancing production of the crop. However another economic study which took place in Mali showed that when all uses of Jatropha were taken into consideration, a rate of return of 135% could be achieved (Dinh et al., 2009).

Veljkovic et al., (2006) noted that biodiesel, which is made from renewable sources, consists of the simple alkyl esters of fatty acids. As a future prospective fuel, biodiesel has to compete economically with petroleum diesel fuels. The use of the less expensive feedstock containing fatty acids such as inedible oils, animal fats, waste food oil and byproducts of the refining vegetables oils reduces the costs of producing biodiesel. Therefore the availability and sustainability of supplies of less expensive feedstock will be a crucial determinant in competitively delivering biodiesel to commercial fuel filling stations. Such less expensive feedstock can come from inedible vegetable oils, mostly produced by seed-bearing trees and shrubs such as Jatropha curcas, a plant which has no competing food uses and which grows widely in tropical and subtropical climates across the world (Openshaw, 2000). Berchmans and Hirata (2008) developed a technique to produce biodiesel from crude Jatropha curcas seed oil having high free fatty acids (15% FFA). The high FFA level of the oil was reduced to less than 1% by a two-step pretreatment process. The first step was carried out with 0.60 w/w methanol-to-oil ratio in the presence of 1% w/w H2SO4 as an acid catalyst in 1-hr reaction at 500C. After the reaction, the mixture was allowed to settle for 2 hr and the methanol-water mixture which separated at the top layer was removed. The second step involved trans esterification using 0.24 w/w methanol to oil and 1.4% w/w NaOH to oil as alkaline catalyst to produce biodiesel at 650C. The final yield for methyl esters of fatty acids was achieved for 90% in 2 hr.

experiments. Experimental results revealed that a 12:1 molar ratio of methanol to oil, addition of 1.5% (w/v) CaO catalyst, 70°C reaction temperature, 2% water content in the oil produced more than 95% biodiesel yield after 3 hours reaction time. Calcium oxide activated with ammonium carbonate was an efficient super base catalyst for a high yield transesterification reaction and the base strength of CaO was more than 26.5 after dipping in ammonium carbonate solution followed by calcinations. Transesterification of Jatropha oil using supercritical methanol was also studied under the range of temperature from 120°C to 250°C, and range of pressure from 5 — 37 bars using superbase catalyst CaO and acid catalyst. The reaction products were analyzed for their content of glycerol by high performance liquid chromatography (HPLC) and this revealed that the process of supercritical transesterification achieved a yield of more than 95% after 1 hour.

The typical fuel properties of Jatropha curcas L, oil are as shown in Table 4 below. These properties show that jatropha biodiesel is a good quality biofuel.

In contemporary times, a great deal of interest has been generated worldwide regarding the use of biofuels namely biogas, bioethanol and biodiesel for energy supply. The most ambitious goal thus far in respect of the development and exploitation of renewable energy sources appear to be that articulated by the European Renewable Energy Council. According to European Renewable Energy Council EREC (2010) in March 2007, the Heads of States and Governments of the 27 EU Member States adopted a binding target of 20% renewable energy in final energy consumption by 2020 and 100% by 2050. Combined with the commitment to improve energy efficiency by 20% until 2020 and to reduce greenhouse gas emissions by 20% (or respectively 30% in case of a new international climate agreement) against the 1990 level, Europe’s political leaders paved the way for a more sustainable energy future for the European Union and for the next generations. In order to reach the binding overall target of at least 20% renewable energy by 2020, the development of all existing renewable energy sources as well as a balanced deployment in the heating and cooling, electricity and transport sectors is needed. According to estimates of the European renewable energy industry around 40% of electricity demand will be generated with renewable energy sources by 2020 (EREC, 2010). Furthermore, the new Renewable Energy Directive (RED) will undoubtedly stimulate the renewable energy heating and cooling market, and according to EREC’s projections, up to 25% of heating and cooling consumption can come from renewable energy by 2020. Similar kind of awareness is evident in other

regions of the world and cogent efforts are being made to increase the renewable energy share of the energy profile and reduce overdependence on fossil fuels.

For about 3 decades, Brazil has been in the forefront of using renewable energy in the form of bioethanol derived mainly from sugarcane to power fuel-flex vehicles or as oxygenate to gasoline and has made a remarkable success of it. Likewise, the USA has also to some extent used bioethanol to power vehicles. Bioethanol is the biofuel most widely used for transportation worldwide. The global annual production of fuel ethanol is around 40 to 50 billion litres, of which 90 percent is produced by the USA and Brazil from maize and sugarcane respectively (World Bank, 2008). Global ethanol production has seen steady growth since the search for alternatives to petroleum was prompted by the oil crisis of 1973/1974. The USA is now the largest consumer of bioethanol, followed by Brazil. Together they consume 30 billion litres, or three quarters of global production (Licht, 2005). The Economist (2005) reported that as at that time Germany was raising its output of biodiesel by 50% per year; USA was boosting its ethanol production by 30% per year; France aimed to triple its output of biodiesel and ethanol by 2007; China had just built the largest ethanol plant in the world; and also that Brazil was producing around 4 billion litres of ethanol per year, and hoped to export 8 billion litres per year by 2010. China’s Ministry of Science and Technology plans that the country would attain 12 million tonnes of biodiesel production by the year 2020 (GTZ, 2006).

According to OECD (2008), the global ethanol and biodiesel production in 2007 is given in Table 1. Certainly, successes recorded as regards exploitation and use of other biomass for energy supply, will further enhance global energy security. Some of the themes involved in this are discussed in this chapter.

Source: OECD (2008)

Table 1. Global Ethanol and Biodiesel Production for 2007 (in million litres)

There must be suitable moisture content of the feedstock as the microorganisms’ excretive and other metabolic processes require water. The moisture content should normally be around 90% of the mass of the total contents (Buren 1983). Both too much and too little water are harmful, with too much water the rate of production per unit volume in the digester will fall, preventing optimum use of the digester. If the moisture content is too low, acetic acids will accumulate inhibiting the digestion process and hence production. Furthermore, a rather thick scum will form on the surface of the substrate. This scum may prevent effective mixing of the charge in the digester.