CHAPTER 3 A STUDY ON BIODIESEL FEEDSTOCKS

Transcription

1 58 CHAPTER 3 A STUDY ON BIODIESEL FEEDSTOCKS 3.1 INTRODUCTION This chapter provides an overview of biodiesel feedstocks from different sources. A rapid increase in biodiesel production capacity and governmental mandates for alternative fuel usage around the world in the last several years has necessitated the urge for development of alternative biodiesel feedstocks. As the present day conditions does not appear possible to meet the increased production capacity and mandated demand with traditional sources of biodiesel (palm, and pre-heated oil and used cooking oils) (Vellguth, 1998; Sidibe et al. 2010). India imports over 70% of the petroleum products and therefore the nation as whole interests in reducing the costs and thereby experiences supplement growth with biofuel in the near future. However, because food security is given higher priority and so the government s biofuel program is being implemented cautiously so as not to displace food production. India is one of the world s largest importers of vegetable oils. The biofuel program will be used to help off-set petroleum imports to the extent that feedstock surpluses are available that will not undermine efforts toward self-reliance in food supply. Therefore, India (similar to China) plans to focus the future biofuel feedstock production on non-edible oils, animal fats and food processing byproducts that will not compete with food crops for agricultural land. Examples include molasses for ethanol and Jatropha and other treebased oils for biodiesel. The ethanol program has begun modestly,

2 59 coincidentally during good sugar cane harvest years. In contrast, the biodiesel program is yet to start off. Desirable characteristics of alternative oil seed feedstocks for biodiesel production include adaptability to local growing conditions (rainfall, soil type, latitude, etc.), regional availability, high oil content, favorable fatty acid composition, compatibility with existing farm infrastructure, low agricultural inputs (water, fertilizer, pesticides), definable growth season, uniform seed maturation rates, potential markets for agricultural byproducts, and the ability to grow in agriculturally undesirable lands and/or in the Off-season from conventional commodity crops. Biodiesel fuels prepared from feedstocks that meet at least a majority of the above criteria will hold the most promise as alternatives to petrol or diesel (Bhatt et al. 2004; Baiju et al. 2009). 3.2 BIODIESELS FEEDSTOCK FROM EDIBLE OIL Biodiesel is a diesel replacement fuel for use in CI engine. It is manufactured from plant oils (palm oil, cotton seed oil, corn oil), recycled cooking greases or oils (e.g., yellow grease), or animal fats (beef tallow, pork lard). It is an inevitable fact that plants produce oils from sunlight and air, and can do so year after year on croplands. Hence, these oils are called for as renewable. Animal fats are produced when the animal consumes plants or animals, and these too are renewable. Used cooking oils are mostly plant based, but may Also, contain animal fats. Used cooking oils are both recyclable and renewable (Radich 2006; Kemp 2006). Biodiesel has many advantages and are as follows: It is renewable. It is energy efficient.

3 60 It displaces petroleum-derived diesel fuel. It can be used as a 20% blend in most diesel equipment with no or only minor modifications. It can reduce global warming gas emissions. It can reduce tailpipe emissions, including air toxic. It is nontoxic, biodegradable, and suitable for sensitive environments. Rapeseed oil has 82% of the share of the world s biodiesel feedstock, followed by sunflower oil (10 per cent), soybean (5 percent) and palm oil (3 per cent). The choice of feed is country specific and depends on availability. The United States uses soybean, Europe rapeseed and sunflower, Canada canola, Japan animal fat and Malaysia palm oil. In India, non-edible oil is most suitable as biodiesel feedstock since the demand for edible oil exceeds the domestic supply. It is estimated that the potential availability of such oils in India amounts to about 1 million tons per year; the most abundant oil sources are sal oil (180,000 t), mahua (180,000 t), neem oil (100,000 t) and Pongamia Pinnata, also as karanja oil (55,000 t) (Sharma et al. 2008). However, based on extensive research carried out in IC engine research centers, it was decided to use pre-heated palm oil for a small percentage of diesel blended on a volume basis with palm oil and corn oil as the feedstock. Palm oil and corn oil were originally developed in Malaysia and USA and is a tree-borne oilseed which grows in dry, arid land. Table 3.1 shows the oil yields per kg of one hectare (Murugesan et al. 2009).

4 61 Table 3.1 Oil yields: kg/ha Corn: 145 Peanuts: 890 Cotton: 273 Poppy seed: 978 Soybean: 375 Rapeseed: 1000 Mustard: 481 Castor: 1188 Camelina: 490 Jojoba: 1528 Safflower: 655 Jatropha: 1590 Rice: 696 Macadam: 1887 Sunflower: 800 Avocado: 2217 Coconut: 2260 Oil palm: BIODIESEL FEEDSTOCK FROM NON EDIBLE OIL The use of non-edible vegetable oils as compared to edible oils is very significant in developing countries because of the tremendous demand for edible oils as food and they are far too expensive to be used as fuel at present. Many researchers are working on non-edible oils of jatropha curcus, pongamia pinnata and mesua ferrea seeds for the production of biodiesel. The disadvantages of vegetable oils as a diesel fuel substitute are: Higher viscosity; Lower volatility; The reactivity of unsaturated hydrocarbon chains. Biodiesel production efforts are focused on using non-edible oils from plants (palm, Jatropha curcas, Pongamia pinata and other tree borne oilseeds) and animal fats like fish oil. The focus is to encourage the use of wastelands and other unproductive land for the cultivation of these relatively

5 62 hardy new bio-fuel crops. The government of India (GOI) does not want bio-fuel feedstock crop cultivation to compete with food crops for scarce agricultural land and water. An estimated 55.3 million hectares are considered wasteland in India, which could be brought into productive use by raising biodiesel crops. The GOI s policy is also driven by the fact that bio-fuel crop cultivation in wastelands would provide additional employment to the vast rural population in India. There arises the question of the definition of wastelands as some grazing or less intensive dry land farming may be taking place on these wastelands. Nevertheless, biodiesel production from non-edible oilseeds, etc. is still in the research and development stage in India (Rao et al. 2008; Lin et al. 2011). 3.4 BIODIESEL FEEDSTOCK FROM WASTE COOKING OIL The feed stock of waste cooking oil as biodiesel in a diesel engine is an economical source and an effective strategy for reducing cost, and solves the problem of waste oil disposal. The used cooking oil (WCO) has properties different from the properties of refined / crude fresh cooking oils. During frying process, the presence of heat and water accelerates the hydrolysis of triglycerides and increases content of free fatty acids in the oil. Oxidation stability of the oil is disturbed because of the contact of hot oil with food, and peroxide value of oil increases. Viscosity of oil increases considerably, because of the formation of dimeric and polymeric acids and glycerides. Correspondingly, molecular mass and iodine value decreases and saponification value and density increases. The free fatty acid and moisture content are important process parameters for the biodiesel production i.e. transesterification process. They are the vital key for determining the viability of the vegetable oil transesterification process. Thus, the process of biodiesel production from WCO differs from that of fresh oil. The problem with processing WCO is

6 63 that they usually contain large amounts of free fatty acids that cannot be converted to biodiesel using an alkaline catalyst due to formation of salts (soap) and hence smaller is the conversion efficiency. The soaps prevent separations of biodiesel from glycerin fraction and are in agreement with literature (Canakci, 2007; Enweremadu and Rutto 2010) 3.5 SUMMARY pronged: In summary, India s strategy for promoting bio-fuels are one Promote the use of biodiesel derived from non-edible oils and oil waste for blending with diesel Diesel consumption in India is estimated at million tons in Given this figure, the biodiesel required for 20 per cent blending would be million tons. Obtaining biodiesel in this amount is quite a daunting task and involves about 14 million hectares of land under biodiesel feedstock cultivation. India may have to import biodiesel or vegetable oil feedstock or even oilseeds. The objective of this summary was to give an overview of potential sources of feedstock for biodiesel production, their merits and demerits, and the environmental incentives for promoting biofuel generations from such a source. The benefit analysis of the use of WCO as a fuel source was further discussed. The summary of our findings clearly indicated the many merits of the generations of biodiesel from WCO as a sustainable, most potential and yet to be fully exploited energy

7 64 source. The research findings further establish the need to harness WCO in biodiesel production. As per above literature analyses on cost, environmental benefits and feedstock availability, there is tremendous potentials for palm oil, corn oil, waste cooking cotton seed and rice bran oil as biodiesel blends. Hence, the choice of these fuels for current investigations.