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Liquid Fuel from Biomass: an Overview

Liquid Fuel from Biomass: an Overview

Journal of Scientific & Industrial Research Vol. 64, November 2005, pp. 822-831

Liquid from : An overview

Padma Vasudevan*, Satyawati Sharma and Ashwani Kumar Centre for Rural Development & Technology, Indian Institute of Technology, Hauz Khas, New Delhi 110 016

With depleting oil resources and negative environmental impacts associated with the use of petro , there is a renewed interest in biomass based fuels, which can still form the base for sustainable development in terms of techno- economics, environmental as well as socio-cultural considerations. As it is a locally available resource, energy equity can also be achieved at global levels and developing countries would stand to gain. However, to exploit the potential of biomass, more work is needed for converting it efficiently into modern energy carriers at competitive prices, supported by relevant policies. Currently, bioethanol and have already reached commercial markets, especially as blends with petro fuels. This paper gives an overview on biofuels covering the current and futuristic trends with respect to production and utilization of , vegetable oil based biodiesel and biocrude, emphasizing on the benefits to rural economy. Keywords: Biodiesel, Bioethanol, Biomass, Liquid fuel, Vegetable oil IPC Code: C10L1/02

Introduction Liquid Biofuels Energy content of the biomass annually produced The cultivation, processing and use of liquid globally exceeds today’s world energy consumption by biofuels emit less climate-relevant CO 2 than that of several factors 1. Biomass can be converted into solid, fuels from fossil sources. Biofuels are inherently more liquid or gaseous fuels through thermo-chemical and biodegradable than fossil fuels, and therefore repre- biological routes. Liquid fuels, which are biofuels in sent a lower threat for inland and coastal waters. This, the liquid form, are of special interest as petrol and and the fact that biofuels are mostly consumed where diesel substitutes, in running internal they are produced, means that the risk of danger engines, especially for transportation. The rising cost of resulting from transportation is greatly minimized. -based liquid fuels due to the depletion of oil Processing of biofuels and raw materials can pave sources, has brought biofuels back into focus. way for multi-functional farming, which would lead to a new source of income and jobs in the area. For Biofuel is a non-polluting, locally available, example, if European Union (EU) had a sustained accessible and reliable fuel obtained from renewable demand for 2 million tons of biofuel, an estimated sources. For propagating biofuels, in addition to 2,000 jobs could be created in plant cultivation itself developing relevant technologies, sustainable produc- and 7,000 jobs would be generated in processing 1. tion and availability of raw materials as well as Given the labour surplus in developing countries with marketing of final products have to be ensured. Raw lower level of mechanization, employment potential is material, technology to be adopted and the policy much higher 5. Use of green energy sources, inte- issues would vary from country to country 2. Hall 3 grating biomass production with agriculture, forestry analyzed the potential of biomass energy in the and wasteland regeneration would directly benefit context of “Industrialized Countries”. Country papers rural economy through employment generation and such as the “Potential of Liquid Biofuel in France” are 4 increase of land productivity, at the same time also available . A detailed report on Biofuel, by the 6 5 reducing the rate of CO 2 emission . Planning Commission, India and reports of various other ministries of Government of India have specifi- Types of Liquid Biofuels and Raw Material Sources cally emphasised the direct and indirect benefits of Liquid biofuels being considered world over fall into using biofuels. the following categories: i) Alcohols; ii) Plant seed oils; and iii) Biocrude and synthetic oils. Globally these ______are obtained from the following four broad categories *Author for correspondence of biomass sources: 1) Plantations specially raised for E-mail: [email protected] , [email protected] producing energy or energy and food such as energy VASUDEVAN et al : LIQUID FUEL FROM BIOMASS: AN OVERVIEW 823

Table 1 Current and projected and diesel tuents of plant, which can be directly extracted from consumption (billion litres) 6 biomass. These are generally a complex mixture of Region Gasoline Diesel lipids, triglycerides, waxes, terpenoids, polysterol and 2000 2020 2000 2020 other modified isoprenoids that can be catalytically Africa 30 65 34 65 upgraded for use as liquid fuels. The possibility of Asea 30 63 60 111 producing liquid fuel from biocrude have been India 8 22 43 100 considered using different kinds of raw materials, Other Asia 186 397 253 469 such as wood 7,8 and laticiferous plant species 9 such as Brazil 24 50 3 61 Euphorbiaceae , Asclepiadaceae , Convolvulaceae and Other South America 30 56 34 56 Moraceae . Some of the methods used are pyrolysis, North and Central America 561 778 242 293 hydropyrolysis and catalytic cracking. Oceania 22 32 16 21 Europe (including Russia) 242 386 333 439 Applications of Liquid Biofuels World 1132 1829 1050 1614 The liquid fuels are used for: a) Pure heat produc- tion; b) Electricity generation and combined heat pro- Table 2 Properties of conventional and fuels 5 duction (CHP); and c) Vehicular transport. The first Characteristics Diesel Gasoline two come under stationary application in diesel Energy content, MJ/kg 42.5 44.0 26.9 2 pumps for irrigation and electricity generation. In this Kin Viscosity, mm /s 4.01 0.6 1.5 case, weight factor, which is always relevant to Boiling point, oC 140-360 37-205 79 , oC 55-65 -40 13 mobile applications, can be disregarded. In the latter, Auto ignition temperature, oC 230 300 366 as in vehicular fuels for light and heavy vehicles, Flammability limits, % gas in air 0.0-5.6 1.4-7.6 3.3-19.0 weight factor has to be considered. Automobile Motor Octane Number - 80-9- 89 engines may be divided into two groups: (a) Constant 45-55 0-5 5 volume cycle, spark ignition engines Fuel for this kind of engines is the gasoline fraction of crude oil plantations, petro crops, agro-forestry etc.; 2) Agricul- used for light vehicles (car, two wheeler, three tural residues and wastes including manure, straw, bag- wheelers); and (b) Constant pressure cycle engine, asse, and forest wastes; 3) Uncultivated biomass such alternately called compression ignition engine - Fuel as weeds; and 4) Organic urban or industrial wastes. for this kind of engine is diesel, used for heavy Alcohols vehicles, in railway transport, tractors etc. Biodiesel is Bioethanol is produced by of sugar best suited to replace petro diesel, whose consumption and starchy crops. Cellulosic biomass is also being is likely to go up substantially (Table 1). experimented for the production of bioethanol as this 5 technology will help in using biomass residues from Bioethanol as a Substitute to Gasoline Petroleum reserves are finite. Emissions from agricultural crops and forestry. Bio- can be engines using gasoline have NO , SO , CO and parti- obtained by thermo-chemical degradation of ligno- x 2 2 culate matter (PM), which cause pollution. Gasoline cellulosic material. has a knocking tendency. Tetra ethyl lead (TEL), as Biodiesel from Vegetable Seed Oils an additive, improves the anti-knocking rating of the Seed oils are combustible and have great potential to fuel dramatically. However, due to harmful effects of be used as biofuels. In principle, any vegetable or seed lead, it has been banned. or cyclic com- oil which essentially comprises triglycerides of long pounds also increase the . Benzene is, chain saturated and unsaturated fatty acids, can be however, a known carcinogenic material. Addition of burnt in a . It is interesting to note that oxygenated compounds helps in anti knocking. Rudolph Diesel in the preface of his patent of 1912 Ethanol as automotive fuel is advantageous as it wrote “use of vegetable oil for engine fuel may seem contains oxygen (35%) based on biomass which is a insignificant today but such oil may become in the renewable material. It reduces vehicular emissions of course of time, as important as petroleum”. Biodiesel is (HC) and carbon monoxide (CO) and vegetable oils modified by transesterification to replace eliminates the use of lead, benzene, butadiene etc. The the glycerol by methyl or ethyl groups. calorific value of ethanol is lower (by 40%) than that Biocrude of gasoline, but increased efficiency in its use partly They are low molecular weight non-polar consti- compensates for this (Table 2). 824 J SCI IND RES VOL. 64, NOVEMBER 2005

Blends (<10%) of ethanol do not present any non-ferrous). Standards for ethanol use as fuel problems. Infact, as compared to gasoline, in this case blending have been prescribed world over, Govt of emission is decreased (HC 18%, CO 18%, NO x 10%). India has initiated 5% ethanol-blended petrol with There is a further decrease in increasing the ethanol effect from 1 st Jan 2003 and 10% ethanol blended content. However, higher blends (> 20%) pose certain petrol is also being envisaged 10 . Ethanol-diesel difficulties: (i) Higher aldehyde emissions; (ii) Corro- (15:85) emulsions can also give beneficial results in siveness, affecting metallic parts; (iii) Higher latent terms of emission reduction in diesel engines 11,12 heat of vaporisation causing startability problem; (iv) (41% PM, 5% NO x). The supply and demand in 2020 Higher evaporation losses due to higher vapour of cane ethanol blending has projected Brazil on top pressure; and (v) Requiring large fuel tank due to followed by India (Table 3). lower calorific value. Ethanol is corrosive, absorbs moisture readily and can affect metallic parts (ferrous/ Biodiesel as Substitute to Petro Diesel 5

Biodiesel has higher flash point temperature Table 3 Cane ethanol blending: Supply and demand in 2020 (billion litres) 6 (>100°C), higher cetane number, lower sulphur content and lower aromatics than that of conventional Region Demand Supply Balance . It could also be expected to reduce 10% gasoline (E4 13 +3% diesel scenario) exhaust emissions due to fuel containing oxygen . Africa 9 22 13 Presently, it is well established that significant Asean 10 29 19 reductions in emissions can be achieved by use of 14,15 India 6 49 43 biodiesel . Like other fossil fuels, High Speed Other Asia 56 23 -33 Diesel (HSD) also makes net addition of carbon to the Brazil 7 62 55 atmosphere. Further, petro diesel emits PM, especially Other South America 8 17 9 below micron 2.5, which gets lodged in lungs causing North and Central America 88 31 -57 reduction in its capacity. PM may carry un-burnt oil, Oceania 4 7 3 which is carcinogenic. Also CO, HC, S and polycyclic Europe (including Russia) 52 0 -52 aromatic (PAH) emissions could be World 239 239 0 high. A 15% ethanol-diesel blend reduces PM Table 4 Properties of different methyl esters compared to emission. However, ethanol diesel blending requires 5 diesel fuel emulsifier and there are certain storage and technical Fuel Property Rapeseed Soybean No. 2 problems. Biodiesel is fatty acid ethyl or methyl ester methyl methyl Diesel and has properties similar to petroleum diesel (Table ester ester fuel 4). Studies conducted with biodiesel on engines Formula C18-C19 C18-C19 C8-C25 (Table 5) have shown reduction in PM (25-50%), HC, Specific gravity 0.88 0.87 0.81 CO and PAH. However, a marginal increase in NO Pour point, °C -15 -3 -23 x (1-6%) is reported. This can be taken care of either by Viscosity mPa at 20°C 3.6 3.6 2.6-4.1 5,16 Lower Heating Value, kJ/l 37 32 35-37 optimization of engine parts or by using a catalyst . Flash Point, °C 179 -- 74 In conventional diesel fuels, additives for lubricity Cetane Number 62 52 40-55 of fuel injection pump (FIP) are needed. Biodiesel is

Table 5 Emission results of biodiesel and blends tests on IDI diesel engine 5

Specifications PM CO HC NO X HC+NO X g/km g/km g/km g/km g/km BS-II limit 0.17 1.5 1.2 Base line 0.129 0.77 0.37 0.79 1.16 With 10 % blend 0.093 0.65 0.22 0.83 1.04 With 15 % blend 0.080 0.62 0.16 0.89 1.05 % Improvement with respect to the base line 10 % blend 28 15 41 -4 10 15 % blend 38 20 50 -12 10

Test Cycle: EEC+EUDC 90 kmph Cold Start (Mahindra & Mahindra)

VASUDEVAN et al : LIQUID FUEL FROM BIOMASS: AN OVERVIEW 825

reported to have superior lubricity. Its blending with A) Sugar to Ethanol Production petro diesel to increase flash point of the blend is In producing ethanol from sugar rich crops, sugar useful, particularly in India, where petro diesel flash is fermented to alcohol using yeasts and other point is 35 oC (well below the world average of 55 oC). microbes. The fermentation process consists of This is important for safety. The viscosity of biodiesel breaking of starchy and sugary material into is higher and may lead to gum formation in injector, individual sugar molecules and then fermenting the cylinder liner etc. Biodiesel can be blended in any sugar into ethanol and CO 2. The fermentation of ratio with petroleum diesel. The existing engines can glucose/sugar to ethanol is energy efficient (93% of use 20% biodiesel blend without any modification and the feed energy is converted as ethanol and only a reduction in torque output. Biodiesel is already in the small amount is taken by yeast). commercial markets. USA uses B20 (20% blend) and [C 6H10 O5]n + nH 2O → nC 6H12 O6 B100 biodiesel. France uses B5 (5% blend) as mandatory in all diesel fuel. In EU, 5-15% blends are C6H12 O6 → 2C 2H5OH + 2CO 2 in use. The medium scale production of biodiesel on commercial basis has been developed in France, A final step purifies ethanol to desired concen- Germany, Italy, Austria and the USA 17 . They tration and usually removes all water to produce produced 1.5 million tons of biodiesel. In Philippines, ‘anhydrous ethanol’ that can be blended with diesel is mixed with coconut oil and the blend is used gasoline. By fermentation alone, not more than 10 in tractors, buses and trucks, but it is not feasible in percent ethanol can be achieved. Distilling fermented cooler countries where viscosity of oil increases and liquor can provide a pure (95%) ethanol. Water in can cause damage to fuel pumps. ethanol is undesirable in its use in gasoline blend and anhydrous alcohol (>99%) is required. Ethanol Biomethanol (95.6%) forms constant boiling mixture with water It is produced from synthetic gas or biogas and that does not allow simple to meet the evaluated as a fuel for internal combustion engines 18 . purpose. As a solution, azeotrophic distillation Methanol can be used in blend with conventional through solvent benzene or cyclohexane is used. fuels (without engine modification) or pure as a fuel. Azeotrophic distillation, however, increases produc- It can be used in traditional combustion engines and tion cost of ethanol considerably. A cost effective in direct cells, but it can also be used as solution is to use molecular sieve to eliminate water a base product for making biodiesel from vegetable [Pressure Swing Adsorption-Molecular Sieve Dehy- oils. The production of methanol is a cost intensive dration Technology (MSDH)]. A synthetic adsorbent chemical process. Therefore, in current conditions, is used to dehydrate alcohol and to a high level of only waste biomass such as old wood or biowaste is dryness with low energy inputs. Use of vapour phase used to produce methanol. adsorption has resulted into further energy saving in 5 the process . Liquid Fuel Production Processes Today, bioethanol is the most widely used liquid fuel; the world ethanol production (60%) is from 1. Bioethanol Production 5 sugar crops. USA and Brazil are large-scale producers Ethanol can be produced from any biological (65%)10 . India is the largest producer of sugar in the material that has sugar, starch or cellulose. The world and has high potential for ethanol production 19 following are basic steps in converting biomass to (Table 6). bioethanol: 1) Converting biomass to a useable fermentation feedstock (typically some form of sugar) The major source of ethanol produc- can be achieved using a variety of different process tion in Brazil, India and other sugarcane-raising technologies; 2) Fermenting the biomass inter- countries is sugar-molasses route. This provides better mediates using biocatalysts (microorganisms inclu- economy by sale of sugar; molasses becomes the ding yeast and ) to produce ethanol; and byproduct of sugar. 3) Processing the fermentation product to yield Sugarbeet In EU, sugarbeet is preferred. fuel-grade ethanol and byproducts that can be Sugarbeet has certain advantages 5 over sugarcane used to produce other fuels, chemicals, heat and/or (Table 7) as follows: i) Lower cycle (5-6 months) of electricity. crop production; ii) Higher yield (35-40 tons/acre); 826 J SCI IND RES VOL. 64, NOVEMBER 2005

Table 6 Ethanol availability based on production from molasses and its uses in India 19 Year Molasses production Production of alcohol Industrial use Potable use Other uses Surplus availability Ml Gl Ml Ml Ml of alcohol Ml 1998-99 7.00 1.41 534.4 584.0 55.2 238.2 1999-00 8.02 1.65 518.9 622.7 57.6 454.8 2000-01 8.33 1.69 529.3 635.1 58.8 462.7 2001-02 8.77 1.77 539.8 647.8 59.9 527.7 2002-03 9.23 1.87 550.5 660.7 61.0 597.5 2003-04 9.73 1.97 578.0 693.7 70.0 627.5 2004-05 10.24 2.07 606.9 728.3 73.5 665.8 2005-06 10.79 2.19 619.0 746.5 77.2 744.3 2006-07 11.36 2.30 631.4 765.2 81.0 822.8

Table 7 Comparison of cane and sugarbeet 5 Properties Cane Sugarbeet Yield per acre, tons 25-30 35-40 Cycle of crop, months 10-11 5-6 Sugar content on weight, % 12-16 14-18 Sugar yield, tons/acre/y 3.0-4.8 4.9-7.2 Ethanol yield (100%), l/acre/y 1,700-2,700 2,800-4,100 (with one cycle/y) iii) High tolerance to wide range of climatic variation; (monosaccharides), which are enzymatically hydro- and iv) Low water and fertilizer requirement lyzed to yield ethanol under following processes: (compared to sugarcane, sugarbeet requires 35-40% Dilute Acid Hydrolysis Hydrolysis occurs in two water and fertilizers). Ethanol yield from sugarcane is stages to maximize sugar yields from the hemicellulose ~1,700-2,000 l/acre/y while for sugarbeet 2,800-4,100 and cellulose fractions of biomass. The first stage is l/acre/y per unit of land even taking only one crop (no operated under milder conditions to hydrolyze credit for other crops). Harvesting of sugarbeet is also hemicellulose, while the second stage is optimized to easier and it requires lower energy for juice hydrolyze the more resistant cellulose fraction. Liquid extraction. hydrolyzates are recovered from each stage, Sweet sorghum Sweet sorghum can be cultivated neutralized, and fermented to ethanol. There is quite a in temperate and tropical regions, increasing its bit of industrial experience with the dilute acid process. potential benefits. Other crops that can yield oligo- Germany, Japan, and Russia have operated dilute acid saccharides (potatoes, cereals, grapes, etc.) are hydrolysis percolation plants off and on over the past generally not much utilized for bioethanol production 50 years. However, these percolation designs would (with the exception of corn in the USA). However, not survive in a competitive market situation. Today, particular varieties of sweet sorghum recently companies are beginning to look at commercial developed in China, the USA, and the EU have very opportunities for this technology, which combine attractive and economically promising characteristics. recent improvements and niche opportunities to solve India is also producing sweet sorghum. The environmental problems. Dilute acid hydrolysis can be Nimbalkar Agriculture Institute, India has claimed to used to recover sugar from sugarcane bagasse. have developed a variety of sweet sorghum with Concentrated Acid Hydrolysis This process is potential to produce 2-4kl/ha/y of ethanol 20,21 . Sweet based on concentrated acid decrystallization of sorghum produces a very high yield in terms of cellulose followed by dilute acid hydrolysis to sugars. grains, sugar and lignocellulosic biomass (average, 30 Separation of acid from sugars, acid recovery, and dry tons/ha/y). acid re-concentration are critical unit operations.

5 Attempts are being made to commercially convert rice B) Cellulose Biomass to Ethanol Production straw into ethanol and lignocellulosic components of In this, cellulose is converted to simple sugars municipal solid waste to ethanol. VASUDEVAN et al : LIQUID FUEL FROM BIOMASS: AN OVERVIEW 827

Table 8 Properties of biodiesel from different oils 26-29 Vegetable oil Kinematic Cetane Lower heating Cloud point Pour point Flash point Density methyl esters viscosity no. value °C °C °C kg/l (biodiesel) mm 2/s °C MJ/kg

Peanut 4.9 54 33.6 5 - 176 0.883 Soyabean 4.5 45 33.5 1 −7 178 0.885 Babassu 3.6 63 31.8 4 - 127 0.875 Palm 5.7 62 33.5 13 - 164 0.880 Sunflower 4.6 49 33.5 1 - 183 0.860 Tallow - - - 12 9 96 - Diesel 3.06 50 43.8 - −16 76 0.855 20% biodiesel blend 3.2 51 43.2 - −16 128 0.859

Table 9 Properties of vegetable oils 30 Vegetable oil Kinematic Cetane no. Heating value Cloud point Pour point Flash point Density viscosity °C MJ/kg °C °C °C kg/l at 38°C, mm 2/s

Corn 34.9 37.6 39.5 −1.1 −40.0 277 0.9095 Cottonseed 33.5 41.8 39.5 1.7 −15.0 234 0.9148 Linseed 27.2 34.6 39.3 1.7 −15.0 241 0.9236 Rapeseed 37.0 37.6 39.7 −3.9 −31.7 246 0.9115 Safflower 31.3 41.3 39.5 18.3 −6.7 260 0.9144 Sesame 35.5 40.2 39.3 −3.9 −9.4 260 0.9133 Soyabean 32.6 37.9 39.6 −3.9 −12.2 254 0.9138 Sunflower 33.9 37.1 39.6 7.2 −15.0 274 0.9161 Palm 39.6 42.0 - 31.0 - 267 0.9180 Babassu 30.3 38.0 - 20.0 - 150 0.9460 Diesel 3.06 50 43.8 - −16 76 0.855

Enzyme Hydrolysis The goal is to reduce cost of (adhB ) and pyruvate decarboxylase ( pdc )24,25 were cellulase enzymes in bioethanol process by employing encoded in bacteria. cutting-edge and efficient biochemical technologies. Therefore, research is being focused on development 2. Biodiesel Production of biological enzymes that can breakdown cellulose Biodiesel generally refers to fatty acid methyl and hemicellulose. An important process modification esters made by transesterification. This is a chemical is the introduction of simultaneous saccharification process in which feedstock oil or fat reacts with and fermentation (SSF), which is another novel methanol and KOH or other type of catalysts used. process for converting cellulose to ethanol 22 . This has The feedstock can be vegetable oil, such as that recently been improved to include the co-fermentation derived from oil seed crops (soyabean, sunflower, of multiple sugar substrates. In SSF process, rapeseed etc.), waste vegetable oil or animal fat. For cellulose, enzymes and fermenting microbes are com- biodiesel, oil extracted from crushed oil seeds is used, bined, reducing the number of vessels and improving either directly or as heating oil. In seeds, oil energy efficiency. As sugars are produced, fermentive content is around 40 Gj/ton, which is similar to that of organisms convert them to ethanol. Thus, all required diesel at 38-45 GJ/ton 18 . enzymes are produced within the reactor vessel, using The most commonly used oils for the production of same microbial community to produce both the biodiesel 26-30 (Tables 8 & 9) are soybean 31,32 , sun- enzymes that help break down cellulose to sugars and flower 33,34 , palm 35 , rapeseed 36 , canola 37 , cotton seed 38 , 23 to ethanol . Recent studies have employed geneti- Jatropha 39 and pongamia 40 . In India, the high cost of cally engineered Gram-negative bacteria to produce edible oils prevents their use in biodiesel preparation ethanol from sugars with high efficiency for example, but nonedible oils are affordable for biodiesel produc- Zymomonas mobilis genes alcohol dehydrogenase tion. India has more than 100 million ha of waste- 828 J SCI IND RES VOL. 64, NOVEMBER 2005

lands, which can be utilized for the production of two phases 18 . In the first phase, there is easy removal Jatropha (ratanjyot). However, in utilizing Jatropha of glycerol, a valuable industrial by-product. In the seeds on a large scale, due care must be taken with second phase, remaining alcohol/ester mixture is regard to some toxic components 41-50 present in the separated and excess alcohol is recycled. Then the seeds as well as the oil cake. esters are sent to the purification process, which Other tree based oils with significant production consists of water washing, vacuum drying and potentials are sal ( Shorea robusta ), neem filtration. A catalyst is usually used to improve the (Azadirachta indica ), mahua ( Mahua indica )51 , reaction rate and yield. 52 besides karanj ( Pongamia pinnata ) and ratanjyot Transesterification works well when the starting oil (Jatropha curcas ). These oils have great potential to is of high quality. However, quite often low quality make biodiesel for supplementing other conventional oils are used as raw materials for bio-diesel sources. Waste vegetable oils are virtually inexhaus- preparation. In cases, where free fatty acids (FFA) tible source of energy, which might also prove an content of the oil is above 1 percent, difficulties arise additional line of production. These oils contain some due to soap formation, which promotes emulsification degradation products of vegetable oils and foreign during the water washing stage and at an FFA content material. However, analyses of used vegetable oils above 2 percent, process becomes unworkable. The indicate that differences between used and unused fats process variables that influence transesterification are not much and in most cases simple heating and reaction time and conversion are reaction temperature, removal by filtration of solid particles suffices for oil temperature, and ratio of alcohol to oil, mixing 5 subsequent transesterification . intensity, purity of reactants, catalyst type and Transesterification This process is the displace- concentration. Technical details on these have been ment of alcohol from an ester by another alcohol in a the subject of some recent reviews 53 . process similar to hydrolysis and has been widely Catalysts are classified as alkali, acid, or enzyme. used to reduce the viscosity of triglycerides. Most Alkali-catalyzed transesterification is faster than acid- natural triglyceride oils are a mixture of 2-10 fatty catalyzed 54 . Alkalis include sodium hydroxide, acids. The chemical make up of fatty acid moiety in sodium methoxide, potassium hydroxide, potassium the triglyceride depends on which oil is used methoxide, sodium amide, sodium hydride, potassium as the original feedstock and what type of fatty acid it amide and potassium hydride 55 . If glycerides have contains. The transesterification reaction is represen- higher FFA and more water, acid-catalyzed trans- ted by the general equation: esterification is suitable. The acids could be H 2SO 4, RCOOR’ + R” →RCOOR” + R’OH H3PO 4, HCl or organic sulfonic acid. Besides chemical catalysts, enzyme catalysts and If methanol is used in the above reaction, it is termed supercritical alcohol treatment are of interest, given methanolysis. The reaction of triglyceride with the increasing environmental concerns. The use of methanol is represented by the general equation: lipase producing microbial cells immobilized within

CH 2 − O − COR 1 porous biomass support particles (BSPs) in whole cell  Heat biocatalysis is reported to be effective in improving − − + cost efficiency since the immobilization can be CH O COR 2 3CH 3OH →  Catalyst achieved spontaneously during batch cultivation and no purification of lipase is necessary. For example, CH 2 − O − COR 3 Triglyceride Methanol immobilized Rhizopus delemar and Rhizomucor miehei lipases efficiently catalyzed alcoholysis with − R1 COOCH 3 CH 2OH long-chain fatty alcohols even in the presence of 20 +  percent water 56-58 . Lipases catalyze not only R − COOCH + 2 3 CHOH hydrolysis but also esterification and transesteri- +  fication in nonaqueous medium. Methanolysis of R − COOCH CH OH 3 3 2 triacylglycerols (TAGs) with a lipase thus is Fatty acid methyl ester Glycerol considered one of the effective reactions for 59 where, R1, R 2 and R3 are specific fatty acids depending production of biodiesel fuel from waste edible oil . on the triglyceride used. Product recovery is done into An immobilized lipase 60 was employed to catalyze the VASUDEVAN et al : LIQUID FUEL FROM BIOMASS: AN OVERVIEW 829

methanolysis of corn oil in flowing supercritical CO 2 experimental phase. Its use has only been tested in a with high ester conversion (>98%). Use of immo- few diesel vehicles. If diesel vehicles were designed bilizer Rhizopus oryzae for methanolysis of soyabean and produced to run on DME, they would become oil has been reported 61 . inherently very low pollutant emitting vehicles.

3. Biomass Gasification 62 Bio-oil Another approach to convert biomass into liquid or When organic materials are subjected to fast gaseous fuels is direct gasification, which is based on pyrolysis by rapidly heating (450-600 °C) in absence the partial combustion of material in a restricted of air, organic vapour, pyrolysis gases and charcoal supply of air or oxygen to give producer gas 18 , which are produced. Vapours are condensing to liquid fuel consists mainly of CO, H 2 and CH 4. Other possible termed as bio-oil; typically 70-75 percent of feedstock target fuels include methanol, synthetic diesel and can be converted into bio-oil depending upon gasoline (latter two produced using the “Fischer- condition 64 . Bio-oil can be used as liquid fuel in Tropsch” process to build carbon chain molecules), boilers, kilns, turbines and diesel engines. dimethyl ether (DME, a potential alternative fuel for diesel engines with good combustion properties and Conclusions low emissions), and gaseous fuels such as CH 4 and Liquid fuels from biomass have already entered H2. DME and the gaseous fuels are not compatible commercial markets in many countries especially as with today’s gasoline or diesel vehicles and would blends (up to 20-25 %) with gasoline and diesel. need both new types of vehicles (compressed natural Bioethanol production is now well established and the gas or vehicles) and new refueling issue is of making cheap alcohol through the use of infrastructure. waste feed stock such as cellulosic materials by enzyme fermentation techniques. Use of vegetable Fischer-Tropsch (F-T) Fuels oils directly and as micro emulsions and processing F-T process converts “syngas” (CO and H 2) into through pyrolysis etc. for generating diesel substitute diesel fuel and naphtha (basic gasoline) by building have been tried 65 . However, direct use of vegetable polymer chains out of these basic building blocks. oils still faces many technical problems and Typically, a variety of co-products (various transesterification has become the well-established chemicals) are also produced. F-T process is quite route. Here again use of enzymes and immobilized expensive if only gasoline and diesel products are 63 whole cells are being tried for reducing cost of the considered . product. Engine modifications for higher level of biodiesel and other products and new ways of getting Methanol Syngas can also be converted into methanol power, such as the use of fuel cell technology are in through dehydration or other techniques and in fact consideration. Raw materials range from edible to methanol is an intermediate product of F-T process nonedible oils must be selected carefully considering (and is therefore cheaper to produce than F-T gasoline the toxicity and other aspects. Depending on the and diesel). Methanol is somewhat out of favour as a availability in a country, one or the other raw material transportation fuel due to its relatively low energy seems economically viable for production of content and high toxicity, but might be a preferred biomethanol and biodiesel. Every country has scope fuel if fuel cell vehicles are developed with on board for developing biofuels for their energy security, with reforming of hydrogen (since methanol is an excellent con-commitment economic and environmental hydrogen carrier and relatively easily reformed to benefits. However, more R&D is needed on impro- remove the hydrogen). ving production process with better catalysts and increasing yields. With suitable policy support, Dimethyl Ether (DME) infrastructure has to be established ultimately aiming DME also can be produced from syngas, in a at using pure (100%) biofuels. Both the developed manner similar to methanol. It is a promising fuel for and developing countries which have the potential to diesel engines, due to its good combustion and grow biomass, can stand to gain by immediately emissions properties. However, like LPG, it requires adopting currently available technologies and special fuel handling and storage equipment and some participating in R&D for further development with modifications of diesel engines, and is still at an regard to biofuels best suited to their conditions. 830 J SCI IND RES VOL. 64, NOVEMBER 2005

References 22 Sreenath H K, Ethanol production from alfalfa fiber fractions 1 DGS, Ecofys, Planning and Installing Bioenergy Systems by saccharification and fermentation, Process Biochem , 36 (James and James/Earthscan Publishers, London) 2005, 1-3. (2001) 1199-1204. 2 Cadenas A & Cabezudu S, Biofuels as sustainable 23 Hamelinck C, Prospects for ethanol from lignocellulosic technologies: Perspective for less developed countries, in biomass: Techno-economic performance as development Technological Forecasting and Social Change (Elsevier progresses, Utrecht University, Report NWS-E_2003-55. Science Inc., New York) 1998, 83-103. 24 Doran J B, Aldrich, H C & Ingram L O, Saccharification and 3 Hall D O, Biomass energy in industrialized countries- A fermentation of sugar cane bagasse by Klebsiella oxytoca P2 view of the future, Forest ecology & Mgmt , 91 (1997) 17-45. containing chromosomally integrated genes encoding the Zymomonas mobilis ethanol pathway, Biotechnol Bioeng , 44 4 Department of Agriculture and Bioenergy, The potential of (1994) 240–247. liquid biofuels in France, Renewable Energy , 16 (1999) 1084-1089. 25 Ingram L O, Conway T & Alterthum F, Ethanol production by Escherichia coli strains co-expressing Zymomonas pdc 5 Report of The Committee on Development Of Biofuel and adh genes, US Pat 352062 , 1991. (Planning Commission, Govt of India, New Delhi) 2003. 26 Rao P S & Gopalakrishnan KV, Vegetable oils and their 6 Johnson F X, Bioenergy from Sugar Cane for Sustainable methylesters as fuels for diesel engines, Indian J Technol , 29 Development and Climate Mitigation: Options, Impacts and (1991) 292–297. Strategies for International Co-operation (Stockholm 27 Feuge R O & Gros A T, Modification of vegetable oils, VII Environment institute, Sweden) 2002. Alkali catalyzed interesterification of pea-nut oil with 7 Sharma D K, Tiwari M, & Behera B K, Review of integrated ethanol, J Am Oil Chem Soc, 26 (1949) 97. processes to get value-added chemicals and fuels from 28 Dunn R O & Bagby M O, Low-temperature properties of petrocrops, Biores Technol, 49 (1994) 1-6. triglyceride-based diesel fuels: Transesterified methyl esters 8 Gregoire Catherine E & Bain Richard L, Technoeconomic and petroleum middle distillate/ester blends, J Am Oil Chem analysis of the production of biocrude from wood, Biomass Soc , 72 (1995) 895–904. & Bioenergy, 7 (1994) 275-283. 29 Chang D Y Z, Van Gerpen J H, Lee I, Johnson L A, 9 Bhatia V K, Biomass as a non- source- An Hammond E G & Marley S J, Fuel properties and emissions overview, Res & Ind , 33 (1988) 154-161. of soybean oil esters as diesel fuel, J Am Oil Chem Soc , 73 10 The Gazette of India. Part-II, Section-3 (Ministry of (1996) 1549. Petroleum & , Govt of India, N Delhi) Sept 4, 30 Goering C E, Schwab A W, Daugherty M J, Pryde E H & 2002. Heakin A J, Fuel properties of eleven vegetable oils, Trans 11 Ahmed I, Oxygenated diesel: Emissions and performance ASAE, 85 (1982) 1472-1483. characteristics of ethanol-diesel blends in CI engines , SAE 31 Freedman B, Butterfield R O & Pryde E H, (2001) No. 2001-01-2475. Transesterification kinetics of soybean oil, J Am Oil Chem 12 Ali Y, Hanna M A & Borg J E, Optimization of diesel, Soc , 63 (1986) 1357-1380. methyl tallowaste and ethanol blend for reducing emissions 32 Noureddini H & Zhu D, Kinetics of transesterification of from diesel engine, Biores Technol, 52 (1995) 237-243. soybean oil, J Am Oil Chem Soc , 74 (1997) 1457-1463. 13 Subramanian K A, Singal S K, Saxena M & Singhal S, 33 Antolin G F, Tinaut V, Briceno Y, Castano V, Perez C. & Utilization of liquid biofuels in automotive diesel engines: Ramirez A I, Optimization of biodiesel production by An Indian perspective, Biomass & Bioenergy , 29 (2005) 65- sunflower oil transesterification, Biores Technol, 83 (2002) 72. 111-114. 14 Korbitz W, Biodiesel production in Europe and North 34 Mohamed M S & Bornscheuer U T, Improvement in lipase- America, an encouraging prospect, Renewable Energy , 16 catalyzed synthesis of fatty acid methyl esters from (1999) 1078-1083. sunflower oil, Enzyme Microb. Technol, 33 (2003) 97-103. 15 Graboski M S & McCormick R L, Combustion of fat and 35 Darnoko D, & Cheryan M, Continuous production of palm vegetable oil derived fuels in diesel engines, Progr Energy & methyl esters, J Am Oil Chem Soc , 77 (2000) 1269-1272. Combust Sci , 24 (1998) 125-164. 36 Kusdiana D & Saka S, Kinetics of transesterification in 16 Lapuerta Magin, Armas Octavio, Ballesteros Rosario & rapeseed oil to biodiesel fuel as treated in supercritical Fernandez Jesus, Diesel emissions from biofuels derived methanol, Fuel , 80 (2001) 693-698. from Spanish potential vegetable oils, Fuel , 84 (2005) 773- 37 Zhou W, Konar S K & Boocock D G B, Ethyl esters from the 780. single-phase base-catalyzed ethanolysis of vegetable oils, J 17 Biodiesel Development Status Worldwide (Austrian Biofuel Am Oil Chem Soc , 80 (2003) 367-371. Institute, Vienna) 1997. 38 Kose O, Tuter M & Aksoy H A , Immobilized Candida 18 Ralph E H Sinis, The Brilliance of Bioenergy (James & antarctica lipase-catalyzed alcoholysis of cotton seed oil in a James, Science Publishers Ltd) 2002, 220-221. solvent-free medium, Biores Technol, 83 (2002) 125-129. 19 Goel A K, A sugar industry perspective, in Ethanol (Winrock 39 Foidl N, Foidl G, Sanchez M & Mittelbach M, Jatropha International India, New Delhi) 2002, 5. curcas L. as a source for the production of biofuel in 20 Rajvanshi A K, Ethanol from alternative sources, in Ethanol Nicaragua, Biores Technol, 58 (1996) 77-82. (Winrock International India, New Delhi) 2001, 2. 40 Karmee S K, Mahesh P, Ravi R & Chadha A, Kinetics study 21 Joshi H C, Potential of alcohol as bio-fuel in India, of the base catalyzed transesterification of monoglycerides Bioenergy News , 6(4) (2002) 4-5. from Pongamia oil, J Am Oil Chem Soc , 81 (2004) 425-430. VASUDEVAN et al : LIQUID FUEL FROM BIOMASS: AN OVERVIEW 831

41 Siegel, A, Uber die Giftstoffe zweierEuphorbiaceen , Ph D 52 Karmee S K & Chadha A, Preparation of biodiesel from Dissertation, Medicinal Faculty, Imperial Univ, Dorpat.39, crude oil of Pongomia pinnata , Biores Technol , 96 (2005) Felke J, 1913. Uber die Giftstooffe der Samen von Jatropha 1425-1429. curcas, Landw Vers Stat, 82 , 1893427-467. 53 Meher L C, Vidya Sagar D & Naik S N, Technical aspects of 42 Stirpe F, Pession Brizzi A, Lorenzoni E, Strochi P, biodiesel production by transesterification - A review, Montanaro L. & Sperti S, Studies on the proteins from the Renewable & Sust Energy Reviews , (2004) 1–21. seeds of Croton tigilium and Jatropha curcas, Biochem J , 54 Freedman B, Butterfield R O & Pryde E H, 156 (1976) 1-6. Transesterification kinetics of soybean oil, J Am Oil Chem 43 Mourque M, Delphant Beret R & Kassab R, Etude de la Soc , 63 (1986) 1375-1380. toxicité et localisation de latoxalbumine (curcine) des graines 55 Sprules F J & Price D, Production of fatty esters. US Pat de Jatropha curcas Linn., Bull Soc Chim Biol, 41 (1961) 2494366, Jan 10 ( Nopco chemical company) 2 (1950) 366- 517-531. 494. 56 Shimada Y, Sugihara A, Yodono S, Nagao T, Maruyama K, 44 Adolf W, Opferkuch H J & Hecker E, Irritant phorbol Nakano H, Komemushi S. & Tominaga Y. "Enrichment of derivatives from four Jatropha species, Phytochem , 23 ethyl docosahexaenoate by selective alcoholysis with (1984) 129-132. immobilized Rhizopus delemar lipase", J Ferment Bioeng , 84 45 Cano-Asseleih L M, Plumbly R A & Hylands P J, (1997) 138–143. Purification and partial characterization of the 57 Shimada Y, Maruyama K, Sugihara A, Baba T, Komemushi hemagglutination from seeds of Jatropha curcas , J Food S, Moriyama S & Tominaga Y, Purification of ethyl Biochem , 13 (1989) 1-20. docosahexanoate by selective alcoholysis of fatty acid ethyl 46 Aregheore E M, Makkar H P S & Becker K, Assessment of esters with immobilized Rhizomucor miehei lipase, J Am Oil lectin activity in a toxic and a non-toxic variety of Jatropha Chem Soc , 75 (1998) 1565–1571. curcas using latex agglutination and haemagglutination 58 Maruyama K, Shimada Y, Baba T, Ooguri T, Sugihara A, methods and inactivation of lectin by heat treatments, J Sci Tominaga T & Moriyama S, Purification of ethyl Food Agric , 77 (1998) 349-352. docosahexaenoate through selective alcoholysis with 47 Aderibigbe, A O, Johnson C O L E, Makkar H P S & Becker immobilized Rhizomucor miehei lipase J Jpn Oil Chem Soc, K, Chemical composition and effect of heat on organic 49 (2000) 793. matter and nitrogen degradability and some anti-nutritional 59 Shimada Y, Watanabe Y, Sugihara A & Tominaga Y, components of Jatropha meal, Anim Feed Sci Technol , 67 Enzymatic alcoholysis for biodiesel fuel production and (1997) 223-243. application of the reaction to oil processing, J Mole catalysis 48 Makkar H P S & Becker K. Jatropha curcas toxicity: B: Enzymatic , 17 (2002) 133-142. identification of toxic principle(s), in 5th Int Symp on 60 Jackson M A & King J W, Methanolysis of seed oil in Poisonous Plants, San Angelo, Texas, USA, May 19-23, flowing supercritical carbon dioxide, J Am Oil Chem Soc , 73 1997a. (1996) 353-356. 61 Odaa M, Kaiedab M, Hamab S, Yamajia H, Kondoa A, 49 Makkar H P S & Becker K, Potential of J atropha seed cake Izumotoc E & Fukudab H, Facilitatory effect of immobilized as protein supplement in livestock feed and constraints to its lipase-producing Rhizopus oryzae cells on acyl migration in utilization, in Int Symp on Biofuel and Ind Products from biodiesel-fuel production, Biochem Engg J , 23 (2005) 45–51. Jatropha curcas and other Tropical Oil Seed Plants, 23-27 62 IEA, Biofuels for Transport, International Energy Agency , Feb, 1997b. An International Perspective, 2004. 50 Aregheore E M, Becker K & Makkar H P S, Detoxification 63 Novem, BIO-H2: Application of biomass related hydrogen of a toxic variety of Jatropha curcas using heat and chemical production technologies to the Dutch Energy infrastructure, treatments, and preliminary nutritional evaluation with rats, S Report, 2020-2050, (2003). Pac J Nat Sci , 21 (2003) 50-56. 64 Bridgwater A V, Meier D & Radlein D, An overview of fast 51 Ghadge S V & Raheman H, Biodiesel Production of Mahua pyrolysis of biomass, Org Chem, 30 (1999) 1479-1493. (Madhuca indica ) oil having high free fatty acids, Biomass & 65 Jon Van Gerpen, Biodiesel processing and production, Fuel Bioenergy , 28 (2005) 601-605. Proc Technol, 86 (2005) 1097–1107.

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