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CHAPTER 2

LITERATURE REVIEW

The whole world is facing the crises of depletion of fossil fuels as well as the

problem of environmental degradation. The rapid depletion of fossil fuel reserves

with increasing demand and uncertainty in their supply, as well as the rapid rise in

petroleum prices, has stimulated the search for other alternatives to fossil fuels. In

view of this, there is an urgent need to explore new alternatives, which are likely to

reduce our dependency on oil imports as well as can help in protecting the

environment for sustainable development. Many alternative fuels are being recently

explored as potential alternatives for the present high-pollutant diesel fuel derived

from diminishing commercial resources.

Biodiesel emerges as one of the most energy-efficient environmentally friendlyoptions in recent times to full fill the future energy needs. Biodiesel is a renewable

diesel substitute that can be obtained by combining chemically any natural oil or fat

with alcohol. During the last 15 years, biodiesel has progressed from the research

stage to a large scale production in many developing countries. In Indian context,

non-edible oils are emerging as a preferred feedstock and several field trials have

also been made for the production of biodiesel [41].

Vegetable oils either from seasonal plant crops or from perennial forest tree's origin,

after being formulated, have been found suitable for utilization in diesel engines.

Many traditional oil seeds like pongamia glabra, jatropha, mallous philippines,

garcinia indica, thumba, karanja and madhuca indica etc. are available in our

country in abundance, which can be exploited for biodiesel production purpose.

Many vegetable oils, animal fats and recycled cooking greases can also be

transformed into biodiesel. Biodiesel can be used neat or as a diesel additive in

compression ignition engines.

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In this chapter, a detailed survey of available literature is therefore undertaken to

review the different research achievements on vegetable oils and biodiesel as an

alternative fuel for a compression ignition engine, problems associated with purevegetable oils and their possible solutions with their structural details have been

looked into. In addition to this, physical and chemical properties of vegetable oils

as well as biodiesel, fuel formulation techniques, biodiesel production and

utilization, engine combustion, performance and emission characteristics have

also been collected. Efforts have also been made to assess the economic viability

of biodiesel.

2.1 HISTORICAL BACKGROUND OF BIODIESEL

Dr. Rudolf Diesel, who invented the first Diesel Engine in 1895, used only biofuel

in his engine. His visionary statement was The use of vegetable oils for engine fuel

may seem insignificant today, but such oils may become in course of time, as

important as petroleum and coal tar products of the present time. The above

prediction is becoming true today as more and more biodiesel is being used all over

the world. In 1900 at the world fair in Paris, a small version of a diesel engine ran

on plant oil. This was organized by the French society for the support of the Otto

engine. At that time, crude oil was available in abundance; hence, vegetable oils

could not attract as a source of fuel much. Despite the widespread use of fossil

petroleum-derived diesel fuels, interest in vegetable oils as fuel for internal

combustion engines was reported in several countries during the 1920s and 1930s.

While engineers and scientists have been experimenting with vegetable oils as fuel

for a diesel engine since 1900, it is only recently that the necessary fuel properties

and engine parameters for reliable operation have become apparent.

In recent times, due to realization that crude oil is limited and poses a threat to well

being of mankind from emissions of exhaust gases, vegetable oil has been revisited

for its scope as a fuel in compression ignition engines. Some operational problems

were reported due to the high viscosity of vegetable oils compared to petroleum

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diesel fuel, which results in poor atomization of the fuel in the fuel spray and often

leads to deposits and coking of the injectors and valves. To lower the viscosity of

vegetable oil, chemical and thermal processes were tried to make vegetable oil

compatible to compression ignition engines. Attempts to overcome these problemsincluded heating of the vegetable oil, blending it with petroleum-derived diesel fuel

or ethanol, pyrolysis, cracking of the oils, micro-emulsification and

transesterification, where triglycerides from vegetable oils react with a lower

alcohol to produce fatty acid alkyl esters possessing properties similar to mineral

diesel. Transesterification of a vegetable oil was conducted as early as 1853 by

scientists E. Duffy and J. Patrick, many years before the firstdiesel enginebecame

functional. On August 31, 1937, G. Chavanne of the University of Brussels(Belgium) was granted a patent for a procedure for the transformation of vegetable

oils for their uses as fuels. The use of biodiesel was recognized much later and

became technically relevant only after the energy crisis in the year 1973 and

afterwards. More recently, in 1977, Brazilian scientist Expedito Parente invented

and submitted first industrial process for the production of biodiesel for patent [42].

2.2 PROPERTIES OF VEGETABLE OILS AND BIODIESEL

Ideal diesel molecules are saturated non-branched hydrocarbon molecules with

carbon chain length ranging from 12 to 18 whereas vegetable oil molecules are

triglycerides generally with un-branched chains of different lengths and different

degrees of saturation. Vegetable oils mainly contain triglycerides (90 to 98%)

and small amounts of mono and diglycerides. Triglycerides are esters of threefatty acids and a glycerol molecule [43, 44].

http://en.wikipedia.org/wiki/Pyrolysishttp://en.wikipedia.org/wiki/Transesterificationhttp://en.wikipedia.org/wiki/Vegetable_oilhttp://en.wikipedia.org/wiki/Diesel_enginehttp://en.wikipedia.org/wiki/Diesel_enginehttp://en.wikipedia.org/wiki/Vegetable_oilhttp://en.wikipedia.org/wiki/Transesterificationhttp://en.wikipedia.org/wiki/Pyrolysis

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Vegetable oils can be used as alternative fuels because they are biodegradable, non-

toxic, and clean fuels. Vegetable oils and their derivatives as diesel engine fuels

lead to substantial reductions in sulfur, carbon monoxide, polycyclic aromatic

hydrocarbons, smoke and particulate emissions. Number of vegetable oils likekaranja oil, rapeseed oil, rice bran oil, cottonseed oil, sunflower oil and jatropha oil

has been tested as fuels in diesel engines. Studies indicate that, over short periods of

time, neat vegetable oil perform satisfactorily in unmodified diesel engines.

Vegetable oils have high viscosity due to large molecular weight and bulky

molecular structure. The viscosity of liquid fuels affects the flow properties as well

as spray atomization, vaporization, and air/fuel mixture formation. Higher viscosity

also has an adverse effect on the combustion of vegetable oils in existing dieselengines, fuel pumps and injectors. Temperature greatly affects the viscosity of

vegetable oils. It has been reported that the viscosity of oils and fats decreases

almost linearly with temperature. The significant fuel properties of vegetable oils as

listed in Table [2.1], indicates that the kinematic viscosity of vegetable oils varies in

the range from 2767 cSt at 40C. The high viscosity of these oils is due to their

large molecular mass in the range of 600900, which is an order of magnitude

almost 4 times higher than that of diesel. The flash point of vegetable oils is very

high (above 180 C) and the heating values are in the range of 3640 MJ/kg, as

compared to diesel fuels which is about 42-45 MJ/kg. The presence of chemically

bound oxygen in vegetable oils lowers their heating values by about 10%. The

cetane numbers are in the range of 3045. Vegetable oils have comparable energy

density, cetane number, heat of vaporization, and stoichiometric air/fuel ratio to that

of mineral diesel [5, 35, 44]. Vegetable oils can be mixed with conventional diesel

in any proportion and blends can be used successfully in engines [45-48].

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Oils KinematicViscosity

(cSt 40 C)

Density

(kg/m3)

Heating

Value

(MJ/kg)

Cloud

Point

( C)

Pour

Point

( C)

Flash

Point

( C)

Cetane

Number

Carbon

Residue

(w/w)

Diesel 2.75 835 42.25 -15 -20 66 47 0.001Jatropha 49.9 921 39.7 16 8 240 40-45 0.64

Karanja 46.5 929 38.8 13.2 6 248 40 0.64Rapeseed 37 911 39.7 -3.9 -31.7 246 37.5 0.30

Neem 57 938 39.4 8 2 295 47 0.96Sunflower 33.9 916 39.6 7.2 -15 274 37.1 0.23Soybean 32.6 914 39.6 -3.9 -12 254 38 0.27Coconut 27.7 915 37.1 - - 281 52 0.13CottonSeed

33.5 914 39.4 1.7 -15 234 42 -

Rice Bran 28.7 937 38.9 13 1 200 30 0.24Peanut 39.6 902 39.7 12.8 -6.7 271 42 -

Linseed 27.2 923 39.3 1.7 -15 241 34.6 -Palm 39.6 918 36.5 27 -15 271 42 0.043Corn 34.9 909 39.5 -1.1 -40 277 37.6 0.24Thumba 31.52 905 39.78 - - 201 45 -Babassu 30.3 946 - 20 - 150 38 -Tallow - - 40 - - 201 - 6.1

Table [2.1] Properties of Different Vegetable Oils [4, 5, 35, 43, 44, 45, 47, 48]

Due to the molecular similarities of biodiesel to diesel fuel compounds, this

alternative fuel has a chance of fulfilling the requirements of diesel engine [49].

Biodiesel fueled engine emits lower polluting species without the need for

additional emission control equipment. The characteristics of biodiesel are close to

diesel fuels and therefore biodiesel becomes a strong alternative to replace the

diesel fuels [50]. The conversion of triglycerides into methyl or ethyl esters through

the transesterification process reduces the molecular weight to one-third that of the

triglyceride reduces the viscosity by a factor of about eight and increases the

volatility marginally. Biodiesel has viscosity close to diesel fuels. These esters

contain 10 to 11% oxygen by weight, which may encourage more combustion than

hydrocarbon based diesel fuels in an engine [51]. Biodiesel has lower volumetric

heating values (about 12%) than diesel fuels but has a high cetane number and flash

point [52-55]. Some of the enviable fuel properties of biodiesel derived from

different vegetable oils are presented in Table [2.2].

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Biodiesel KinematicViscosity

(cSt 40 C)

Density

(kg/m3)

Heating

Value

(MJ/kg)

Cloud

Point

( C)

Pour

Point

( C)

Flash

Point( C)

Cetane

Number

Carbon

Residue

(w/w)

Jatropha 5.65 879 38.5 13 - 175 50 -Karanja 6.87 897 37.9 - -1 187 49 0.05

Rapeseed 7.2 883 37.37 - -12 - 51 -Neem 15 882 38.5 - - 180 47 -Sunflower 4.6 868 40.58 1 - 183 45-52 -Soybean 4.5 872 39.76 1 -7 178 37-45 1.7Coconut 3.36 866 36.1 - -4 122 56 0.03Peanut 4.9 883 - 5 - 176 54 -Palm 5.7 880 - 13 - 164 62 -Babassu 3.6 879 - 4 - 127 63 -Thumba 3.83-5.86 889 39.37 .5 - 174 53 -Tallow - - - 12 9 96 -- -

Table [2.2] Some Fuel Related Properties of Biodiesel Produced From Different

Vegetable Oils [50-55]

2.3 FUEL FORMULATING TECHNIQUES

The alternative diesel fuels must be technically and environmentally acceptable and

economically viable. From the viewpoint of these requirements, triglycerides

(vegetable oils / animal fats) and their derivatives shall be considered as viable

alternatives for diesel fuels. The problems with substituting triglycerides for diesel

fuels are mostly associated with their high viscosities, low volatilities and

polyunsaturated character. One of the main problems of vegetable oil use in diesel

engines is their higher kinematic viscosity because of heavier triglycerides and

phospholipids, due to which problems occur in pumping and atomization, ring-

sticking, carbon deposits on the piston, cylinder head, ring grooves, etc. Straight

vegetable oils are less suitable as fuels for diesel engines; since they have to be

modified to bring their combustion related properties specially viscosity closer to

mineral diesel. Heating or pyrolysis, dilution or blending, micro-emulsification and

transesterification are some well known techniques available to overcome higher

viscosity related issues associated with the use of vegetable oil in diesel engines and

to make them compatible to the hydrocarbon-based diesel fuels [35, 49, 50, 56].

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2.3.1 Heating or Pyrolysis

Heating or pyrolysis is the process by which high molecular weight compound

breaks into smaller compounds by means of heat with or without catalyst. The

liquid fractions of the thermally decomposed vegetable oils are likely to get

converted into liquid oils. Many investigators have studied the pyrolysis of

triglycerides to obtain products suitable for diesel engines [57, 58]. The pyrolyzate

oils have almost same viscosity, flash point, and pour point that of diesel fuel. The

cetane number of the pyrolyzate oil has been found to be lower. The pyrolyzate oils

from vegetable oils contain acceptable sulphur content, water and sediment and give

acceptable copper corrosion values but unacceptable ash and carbon residue.

Mechanisms for the thermal decomposition of triglycerides are likely to be complex

because of many structures and multiplicity of possible reactions of mixed

triglycerides [59]. Billaud et al. [60] studied the pyrolysis of a mixture of methyl

esters from rapeseed oil in a tubular reactor between 500 and 550C with nitrogen

dilution. The main product obtained was unsaturated methyl ester, which was

chemically similar to petroleum derived fuels.

2.3.2 Dilution or Blending

High viscosity fuels like vegetable oils can be mixed with low viscosity fuel like

diesel to overcome overall viscosity. These blends can then be used as diesel engine

fuels. Dilution of vegetable oils can be accomplished with a solvent, methanol or

ethanol. Vegetable oils can be directly mixed with diesel and may be used to run

diesel engines. Blending of vegetable oil with diesel has been tried successfully by a

number of researchers. The dilution of sunflower oil with diesel fuels in the ratio of

1:3 by volume has been studied and engine tests were carried out by Ziejewski et al.

[61]. They concluded that the blend could not be recommended for a long term use

in the direct injection diesel engines. Pryor et al. [62] had conducted the short term

and long term performance tests with blends of vegetable oil with diesel. In short

term performance test, crude-degummed soybean oil and soybean ethyl ester were

found suitable substitutes for diesel fuel.

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2.3.3 Micro-Emulsification

The formation of micro-emulsions is one of the potential solutions for the problem

of vegetable oil viscosity. A micro-emulsion is a system consists of a liquid

dispersed, with or without an emulsifier, in an immiscible liquid, usually in dropletssmaller than colloidal size. Micro-emulsions are isotropic, clear or translucent

thermodynamically stable dispersions of oil, water, surfactant and often a small

amphiphilic molecule, called co-surfactant. The droplet diameters in micro-

emulsions range from 100 to 1000 . A micro-emulsion can be made of vegetable

oils with an ester and dispersant (co-solvent) of vegetable oils with an alcohol and a

surfactant and a cetane improver, with or without diesel fuels. Micro-emulsions,

because of their alcohol content have lower volumetric heating values than diesel

fuels, but the alcohols have a high latent heat of vaporization and tend to cool the

combustion chamber, which would reduce nozzle coking. Ziejewski et al. [63]

showed that the engine performance was almost same for the micro-emulsified

sunflower oil and the 25 % blend of sunflower oil in diesel.

2.3.4 Transesterification

Transesterification is a most suitable process to convert oils and fats into biodiesel.

It is the most popular reaction used for the conversion of vegetable oils into

biodiesel in order to reduce its viscosity. It is the reaction of an alcohol, in most

cases methanol, with the triglycerides present in oils, fats or recycled grease,

forming biodiesel (fatty acid alkyl esters) and glycerol. The reaction requires heat

and a strong base catalyst, such as sodium hydroxide or potassium hydroxide.

Thetransesterification process involves reacting vegetable oils with alcohols such as

methanol or ethanol in the presence of a catalyst (usually sodium hydroxide or

potassium hydroxide) at about 70C to give the ester and the byproduct, glycerin. It

has been reported that the methyl and ethyl esters of vegetable oil can result in

superior performance than neat vegetable oils.

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2.4 BIODIESEL PRODUCTION BY TRANSESTERIFICATION

PROCESS

Biodiesel fuels are produced by a process called transesterification, in which

various oils (triglycerides) are converted into methyl esters through a chemicalreaction with methanol in the presence of a catalyst, such as sodium or potassium

hydroxide. The byproducts of this chemical reaction are glycerol and water, both of

which are undesirable and needed to be removed from the fuel along with traces of

the methanol, un-reacted triglycerides and catalyst. Biodiesel fuels naturally contain

oxygen, which must be stabilized to avoid storage problems [64-67].

Meher et al. [68] studied the effects of catalyst concentration (KOH), alcohol /oil

molar ratio, temperature and rate of mixing on the transesterification of karanja oil

with methanol. They found that the optimum reaction conditions for methanolysis

of karanja oil was 1% KOH as a catalyst, molar ratio 6:1, reaction temperature 65

C and rate of mixing was 360 rev/min for a period of 3 hours. The yield of methyl

esters was found to be higher by 85% in 15 minutes and reaction was almost

complete in two hours with a yield of 97%. With 12:1 molar ratio or higher, the

reaction was completed within an hour. The reaction was incomplete with a low rateof stirring (180 rev/min). Further in the optimization study, Meher et al. [69] found

that the yield of methyl ester from karanja oil under the optimal condition was 97 to

98%.

Rathore and Madran [70] studied the kinetics of transesterification of karanja oil

into its alkyl esters in supercritical methanol and ethanol without using any catalyst.

The effect of molar ratio and reaction temperature on alkyl ester formation was

studied. It was concluded that the overall yield of ester was more with methanol as

compared to ethanol.

Darnoko and Cheryan [71] reported data on palm oil kinetics. It was observed that

the rate of alkali-catalyzed (KOH) transesterification in a batch reactor increased

with temperature up to 60C. The further increase in temperatures did not reduce

the time to reach the maximum conversion.

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The free fatty acid and moisture content in the material are the key parameters for

determining the viability of the vegetable oil transesterification process. According

to Freedman et al. [72] the free fatty acid content should be lower than 1% to carry

out the alkali catalyzed reaction. In their study they observed that if the acid valuewas greater than 1, more NaOH was required to neutralize the free fatty acids.

Water also caused soap formation, which consumed the catalyst and reduced

catalyst efficiency. The resulting soaps caused an increase in viscosity, formation of

gels and made the separation of glycerol difficult.

Ma et al. [73, 74] studied the effect of free fatty acids and water content in the

transesterification of beef tallow. The presence of water had more negative effects

on the transesterification than free fatty acids. They concluded that for best results,

the water content and the free fatty acid content in beef tallow should be kept below

0.06 % w/w and 0.5 % w/w respectively.

Zullaikah et al. [75] had successfully obtained biodiesel from rice bran oil with high

free fatty acids content. A two-step acid-catalyzed methanolysis process was

employed for the efficient conversion of rice bran oil into fatty acid methyl esters.

Hawash et al. [76]studied the transesterification of jatropha oil using supercritical

methanol in the absence of catalyst under different temperature conditions.

Ramadhas et al. [77] reported the use of acid catalyst followed by alkali catalyst in a

single process using rubber seed oil with high free fatty acid content. The objective

of this study was to develop a process for producing biodiesel from a low-cost

feedstock like crude rubber seed oil.

Iso et al. [78] have studied the transesterification by immobilized lipase in non-

aqueous conditions. Noureddini et al. [79] have investigated the biodiesel

production by lipase catalyst. The time taken to get the 67% yield of biodiesel was

72 hours at room temperature. However, the energy input was zero. The reaction

time and the cost of lipase were hurdles to commercialize lipase processes.

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Various methods of biodiesel production from vegetable oils were also described by

Fukuda et al. [80]. Biodiesel production by transesterification from sunflower oil

was discussed by Antolin G. et al. [81]. Many researchers [82-88] have also

suggested different processes for the production of biodiesel from transesterificationby using different vegetable oils.

2.5 PERFORMANCE, EMISSION AND COMBUSTION BEHAVIOR

OFBIODIESEL ENGINE

Performance, emission and combustion behavior of diesel engine with different

vegetable oils and biodiesel has been evaluated by many researchers and scientists to

establish suitability and feasibility of vegetable oils and biodiesel as an alternative

fuel for diesel engines. The conclusions of previous studies are presented below.

2.5.1 Performance of Diesel Engine Using Vegetable Oils and Biodiesel

A number of researchers and scientists conducted performance tests on compression

ignition engines using different vegetable oils and biodiesel derived from different

feedstocks. The performance parameters such as power output, specific fuel

consumption, exhaust gas temperature and brake thermal efficiency of different

vegetable oils and biodiesel have been reviewed in a detailed manner in the

subsequent paragraphs.

Gerhard Vellguth [89] studied the performance of a direct injection single cylinder

diesel engine with different vegetable oils. He reported that vegetable oils could be

directly used as fuels in diesel engines on a short-term basis with little loss in

efficiency. In long-term operation of engine with vegetable oils, he observed

operational difficulties like carbon deposits, changes in the lubricating oil properties

and ring sticking problems.

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Rao and Gopalkrishna[90] studied the vegetable oils and their methyl esters as fuel

for diesel engines and found that the pure vegetable oils could be used in diesel

engines without any major problems. The direct injection diesel engine given almost

similar output for all the vegetable oils tested.

Altin et al. [91] indicated that the vegetable oils produced from numerous oil seed

crops have high energy content, most of them require some processing to assure safe

use in internal combustion engines. They also conducted experiments on a single

cylinder DI diesel engine to evaluate the performance and exhaust emissions using

sunflower oil, cottonseed oil, soya bean oil and their methyl esters. They found little

power loss, higher particulate emissions and less NOX emissions with neat vegetable

oils. They concluded that raw vegetable oils can be used as fuel in diesel engines

with some modifications. They also indicated that the methyl ester of vegetable oils

is more acceptable substitutes for diesel fuel.

Nwafor et al. [92, 93] performed tests on an indirect injection diesel engine with

rapeseed oil with an injection advance of 3.5 and 5CA BTDC. It was reported that

the delay period was noted to be influenced by the engine load, speed and system

temperature. At 2400 rev/min, there was a significant increase in brake specific fuel

consumption with standard fuel injection timing. There was a significant reduction

in carbon monoxide and carbon dioxide emissions with advanced timing for the

speeds tested. A moderate injection advance was recommended for operations at

low engine speeds. Further, he reported that the fuel consumption of heated and

unheated oil operations at high loads was slightly higher than the diesel fuel

operation. The heated fuel showed a comparative reduction in delay period over the

unheated oil. The overall test results showed that fuel heating was beneficial at low

speed and part-load operations.

Varaprasad et al. [94] investigated the effect of using jatropha oil and esterified

jatropha oil on a single cylinder diesel engine. They found that the brake thermal

efficiency was higher with esterified jatropha oil as compared to raw jatropha oil

but inferior to diesel. They also reported low NOXemission and high smoke levels

with neat jatropha oil as compared to esterified jatropha oil and diesel.

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Parmanik[95] studied the properties and use of jatropha curcas oil and diesel fuel

blends in compression ignition engine. The exhaust gas temperature was observed to

be reduced due to reduced viscosity of the vegetable oil diesel blends. It was found

that the fuel consumption was increased with a higher proportion of the jatrophacurcas oil in the blends. Acceptable thermal efficiencies of the engine were obtained

with blends containing up to 50% (by volume) of jatropha oil.

The tests were also conducted by Forson et al. [96] on a single-cylinder direct-

injection engine operated on diesel fuel, jatropha oil and blends of diesel and

jatropha oil in proportions of 97.4% / 2.6%; 80% / 20%; and 50% / 50% by volume.

The test results showed that jatropha oil can be conveniently used as a diesel

substitute in a diesel engine.

Jajoo and Keoti [97] carried out experiments on a single cylinder diesel engine

using rapeseed oil, soybean oil and their methyl esters as fuel. They revealed that

the engine performance with esters and diesel-vegetable oil blends were comparable

to that of diesel operation. For longer use methyl esters are preferable because of

their lower viscosity and low smoke formation tendency.

Ramadhas, Jayeraj and Muraledharan[98, 99] studied the characterization and effect

of using rubber seed oil in a compression ignition engine and found that the rubber

seed oil can be directly used instead of diesel and does not need any modifications in

the design of the engine. Further, they observed that up to 50% of rubber seed oil can

be substituted for diesel easily in the compression ignition engines without any

major modification and operational difficulties.

Agarwal et al. [100] evaluated the performance and emission characteristics of

linseed oil, mahua oil and rice bran oil blends. It was reported that linseed oil

blends showed comparable thermal efficiency at lower loads; 50% linseed oil

blends were found to be more efficient than other blends. Smoke density was higher

for 50% blends compared to all other linseed oil blends. Smoke density was found

to be higher for mahua blends as compared to mineral diesel at lower engine loads.

Rice bran oil blends showed comparable thermal efficiency to that of diesel fuel

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operation. 20% rice bran oil blend showed minimum brake specific energy

consumption and improved performance.

Herchel et al. [101] found that operation of the test engine with pure coconut oil and

coconut oil diesel blends for a wide range of engine load conditions was

satisfactory even without engine modifications. Increase of coconut oil in the

coconut oil-diesel blends resulted in lower smoke and NOX emissions with an

increase in the brake specific fuel consumption.

Rice et al. [102] presented the results of an engine test with different blends, neat

rapeseed oil and diesel fuel. There were no significant problems with engine

operation using these alternative fuels. The test results showed a reduction in brakethermal efficiency as the amount of rapeseed oil in the blend increases. Reduction of

power-output was also noted with the increased amount of emissions.

Mustafa and Jacobus et al. [103, 104] made an extensive study on a single cylinder

diesel engine operated on a number of vegetable oils like sunflower oil, cottonseed

oil, soya bean oil and peanut oil to provide a detailed comparison of performance

and emissions. They observed that the engine operation with vegetable oils showed

slightly inferior performance. They also observed higher gas phase emissions with

vegetable oils as compared to diesel.

Korete [105] performed the comparative study using 100% rapeseed oil and

commercially available diesel fuel. They observed that the torque and power output

with rapeseed oil were only 2% lower as compared to diesel operation. This was

because of the high viscosity of the rapeseed oil. They found the lower heat release

rate with rapeseed oil than diesel. During the whole operating range they found that

the hydrocarbon and carbon monoxide emissions were higher with rapeseed oil as

compared to neat diesel operation. They also observed slower combustion and

lower maximum gas temperatures in the combustion chamber.

A number of researchers [106-108] also assessed the performance of a compression

ignition engine with different vegetable oils and found that the vegetable oil can be

used as blending component to diesel fuel. Prasad et al. [109] used non-edible oils

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such as pongamia and jatropha in low heat rejection diesel engine. Esterification,

preheating and increase in injection pressure have been tried for utilization of the

vegetable oils in diesel engine. Performance parameters such as the brake specific

energy consumption and exhaust gas temperature have been reported for varyingload for different non-edible oils. The emission of smoke and NOXhas been found

to increase.

Sahoo and Das [110] with other scientists [111-112] investigated diesel engine

performance with biodiesel derived from jatropha oil, Karanja oil and honge oil.

Kumar et al. [113] found longer ignition delay for jatropha oil methyl ester as

compared to diesel fuel on a constant speed diesel engine.

Bhatt, Murthy and Dutta[114] carried out performance evaluation tests on a diesel

engine with karanja oil and its blends with diesel. It was observed that karanja oil

could be easily blended up to 40% (by volume) in diesel without any significant

difference in power output, brake specific fuel consumption and brake thermal

efficiency. The performance of engine with karanja oil blends improved with the

increase in compression ratio from 16:1 to 20:1.

Merve et al. [115] indicated that the torque and brake power output obtained with the

used cooking oil derived biodiesel were 3-5% less than diesel fuel. The engine

exhaust temperature at each engine speed with biodiesel was less than diesel fuel.

Scholl and Sorenson [116]studied the combustion of soya bean oil methyl ester in a

direct injection diesel engine. They found that most of the relevant combustion

parameters for soya bean oil methyl ester such as ignition delay, peak pressure, and

rate of pressure rise were close to those observed for diesel combustion at the same

engine load, speed, timing and nozzle diameter. It was found that ignition delay for

the two fuels were comparable in magnitude and the ignition delay of soya bean oil

methyl ester was found to be more sensitive to nozzle diameter than diesel. Carbon

monoxide emissions from soya bean oil methyl ester was slightly lower,

hydrocarbon emissions reduced drastically, NOX for two fuels were comparable and

smoke numbers for the soya bean oil methyl ester were lower than that of diesel.

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They also observed that the premixed portion of the combustion process had a lower

rate of combustion with the ester as compared to neat diesel.

Clark et al. [117] studied the effects of methyl and ethyl esters of soybean oil on a

4-cylinder diesel engine. They observed that the engine fuelled with soybean esters

resulted in a slightly less power combined with an increase in fuel consumption.

Agarwal [118]transesterified the linseed oil to prepared linseed oil methyl ester and

performed the engine experiments with different blends of biodiesel (linseed oil

methyl ester) with diesel and compared the results with baseline data for diesel

using a single cylinder direct ignition diesel engine. Further Agarwal and Das [119]

studied the biodiesel development and characterization for use as a fuel incompression ignition engine and observed that almost all the important properties of

a biodiesel was in a very close agreement with the diesel oil making it a potential

candidate for partial replacement of diesel fuel. The 20% biodiesel blend was found

to be optimum, which improved the thermal efficiency of the engine by 2.5%,

reduced the exhaust emissions and brake specific fuel consumption.

Al-Widyan et al. [120] have carried out variable speed tests on a single cylinder

direct injection diesel engine using different blends of biodiesel in diesel, produced

from waste vegetable oil. The comparison of the biodiesel blends and the diesel fuel

operation was done in terms of engine performance and exhaust emissions. It was

found that with biodiesel blends, the engine operated smoothly without significant

problems. The blends burnt more efficiently with better fuel economy and further

generated lower emissions.

Zhang and Gerpan [121] investigated the combustion characteristics of the

turbocharged direct injection diesel engine using blends of isopropyl and methyl

esters of soya bean oil with diesel. They found that all fuel blends had similar

combustion behavior. Ignition delay for ester-diesel blend was shorter than diesel

fuel.

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Shaheed and Swain [122] observed that the esters derived from coconut oil have

similar characteristics to diesel fuel with little performance and emission

differences.

Bao and He [123] studied the cotton seed methyl ester as a partial substitute for

diesel oil for single cylinder diesel engines and observed that the mixture of 30%

cotton seed methyl ester and 70% diesel oil was suitable for engine operation.

Biodiesel derived from different feedstock and its blends with diesel were also

investigated for the performance and exhaust emissions by many researchers [124-

139]. They concluded that biodiesel and its blends with diesel can be used

successfully in diesel engines with almost the same efficiency as compared to diesel

and with reduced exhaust emissions.

Amit et al. [140, 141] developed a biodiesel production test rig based on

hydrodynamic cavitation. The hydrodynamic cavitation technique for biodiesel

production, found to be a simple, efficient, time saving, eco-friendly and

industrially viable. They also conducted experiments on four cylinders, direct

injection water cooled diesel engine with diesel and biodiesel blends of citrullus

colocynthis (thumba) oil produced through hydrodynamic cavitation technique.

Biodiesel blend of 30% thumba oil showed relatively higher brake power, brake

thermal efficiency, reduced brake specific fuel consumption and smoke with

favorable P- diagram as compared to diesel fuel.

The transesterification process for production of thumba oil methyl ester has been

analyzed by Karanwal et al. [142] and the various process variables like

temperature, catalyst concentration, amount of methanol and reaction time havebeen optimized with the objective to maximize yield. The optimum conditions for

transesterification of thumba oil with methanol and KOH as catalyst were found to

be 60 C reaction temperature, 6:1 molar ratio of thumba oil to methanol, 0.75%

catalyst (w/w) and 1 hour reaction time.

Egusi melon seed oil was studied by Solomon et al. [143] and Ntui et al. [144] for

the first time as a potential feedstock for biodiesel production. Crude egusi melon

seed oil was transesterified using sodium methoxide as the catalyst at 60 C and

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molar ratio of 1:6 to produce its corresponding methyl esters. Egusi melon oil

methyl ester yield obtained was 82%. All the measured fuel properties of egusi

melon oil methyl ester were almost alike with soya bean and sunflower biodiesel.

Remarkably, the kinematic viscosity of egusi melon oil methyl ester was measuredto be 3.83 mm2/s, a value lower than most of the biodiesel fuels reported.

2.5.2 Exhaust Emission Characteristics of Vegetable Oils and Biodiesel

The use of vegetable oils and biodiesel in a conventional diesel engine results in

substantial reduction of un-burnt hydrocarbons, carbon monoxide and particulate

matter. However, Emissions of nitrogen dioxides are either slightly reduced or

slightly increased depending on the duty cycle and testing methods. The use of

biodiesel can decrease the solid carbon fraction of particulate matter (since the

oxygen in biodiesel enables more complete combustion), eliminates the sulphur

fraction (as there is no sulphur in the fuel), while the soluble or hydrogen fraction

stays almost same. Most of the studies on emission using vegetable oils and

biodiesel have reported lower emissions of un-burnt hydrocarbons, carbon

monoxide, smoke and particulate matter with some increase of NOX.

Nobukazu Takagi and Koichiro Itow [145] conducted experiments on a single

cylinder DI diesel engine with palm oil, rapeseed oil and the blends of palm oil and

rapeseed oil with ethanol and diesel fuel at different fuel temperatures. They found

that the vegetable oils and their blends generated the acceptable performance and

engine exhaust emission levels for short-term operation. Compared to diesel, the

methyl esters of rapeseed oil and palm oil offered lower smoke, NOX emission,

engine noise and higher thermal efficiency.

Wang et al. [146] observed higher carbon monoxide; lower carbon dioxide, lower

HC emissions, except 50% vegetable oil blend, due to higher oxygen content in

vegetable oil. Lower NOX emissions were reported as compared to mineral diesel

due to lower calorific value of vegetable oil.

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H. Raheman and A.G. Phadatare[147] studied the karanja esterified oil and found

that the blends of esterified karanja oil with diesel up to 40% by volume could

replace diesel for getting less emissions. The reduction in exhaust emission together

with an increase in torque, brake power, brake thermal efficiency and reduction inbrake-specific fuel consumption made the blends of karanja esterified oil (B20 and

B40) a suitable alternative fuel for diesel and could help in controlling air pollution.

David Chang and Van Gerpen [148] tested soybean methyl ester as compression

ignition engine fuel. They found that the biodiesel fuelled diesel engine produced a

higher fraction of soluble organic material in its exhaust emission. However,

hydrocarbon emissions were lowered when the engine was fuelled with biodiesel

blends. They reported that the soluble organic fraction was increased when the

fraction of biodiesel was increased in the blends.

In another study, Crookes et al. [149] observed a decrease in NOX emissions with

vegetable oil. They found that at 1500 rev/min and below, diesel NOX emissions

were higher than palm oil. In the speed range of 2500-3500 rev/min, NOX

emissions were found almost same for both oils due to the increase of turbulence

intensity in the combustion chamber which affects the air-fuel mixing process.

Kalligeros et al. [150] conducted experiments on a single cylinder direct injection

petter diesel engine using olive oil and sunflower oils as fuels in different

proportions with marine diesel. They reported lower un-burnt hydrocarbon, carbon

monoxide, nitrogen oxide and particulate with blends compared to neat vegetable

oils.

Nwafor [151] studied the emission characteristics of a diesel engine operating on

rapeseed methyl ester and found that rapeseed methyl ester and its blends with

diesel fuel emitted high carbon dioxide as compared to diesel fuel. Significant

reduction in emission of hydrocarbon was recorded when running on rapeseed

methyl ester. Hydrocarbon emissions observed to increase with increased amount of

diesel fuel in the blend.

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Ken Friis Hansen and Michel Grouleff Jensen [152] used methyl ester of rapeseed

oil for their experiments. They found decrease in hydrocarbon and carbon

monoxide emissions but an increase in NOX and particulate emissions. They also

conducted biological tests and reported that the use of rapeseed oil methyl ester asfuel in diesel engine presents a lower potential health risk than diesel.

Rakopoulos et al. [153] reported that the smoke density significantly increased with

the use of vegetable oil blends of various origins. NOX emissions were slightly

reduced with the use of vegetable oil blends of various origins with respect to

mineral diesel due to lower cetane number (larger premixed combustion part) and

the absence of aromatics. The carbon monoxide emissions were increased and un-

burnt hydrocarbon emissions showed indefinite trends.

Watanabe et al. [154] reported that particulate matter emissions decreased with a

reduction in injection nozzle diameter.

Graboski et al. [155] studied the effect of blending biodiesel (methyl soya ester)

with conventional diesel on performance and emissions characteristics of a diesel

engine. They tested 20%, 35% and 65% biodiesel blends with diesel. By increasing

biodiesel proportions in the blend, increased NOX emission and reduced

hydrocarbons and particulate emissions were observed. There are several reported

results [156-157] of a slight increase in NOX emissions for biodiesel. However,

biodiesels lower sulfur content allows the use of NOX control technologies that

cannot be otherwise used with conventional diesel. Hence, NOXemissions can be

effectively managed and eliminated by engine optimization.

2.5.3 Combustion Behavior of Vegetable Oils and Biodiesel

Heat release analysis of engine pressure data is a means of indirectly depicting the

combustion process occurring in the engine. A detailed experimental description of

combustion evolution in diesel engines is extremely complex because of the

simultaneous formation and oxidation of air/fuel mixture. It is carried out within the

framework of the first law of thermodynamics. The pressure crank angle history ofan engine is affected by combustion, heat transfer and mass loss. The heat release

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pattern alone indicates the affect of combustion. Thermal efficiency and peak

cylinder pressure is very much influenced by the heat release pattern. Heat added

before the TDC increases heat losses, frictional losses and peak cylinder pressure.

During the combustion process the burning proceeds in three distinguishable stages.In the first stage the rate of burning is very high and lasts for only a few crank angle

degrees. It corresponds to the period of rapid pressure rise. The second stage

corresponds to a period of gradually decreasing heat release rate and lasts about 40

CA. Normally about 80% of the heat energy is released in these two phases. The

third stage corresponds to a small but distinguishable rate of heat release persists

throughout the expansion stroke. The heat energy during this period usually amounts

to 20% of the total fuel energy. The different methods for computation of heatrelease rate from cylinder pressure data vary in the degree of accuracy with which

the contents of the cylinder are considered. Some methods are simple and easy to use

and others are complicated and involve extensive computation to achieve accuracy

[158, 159].

Senatore et al. [160] reported that with rapeseed oil methyl ester, heat release

always takes place earlier than mineral diesel, because fuel injection starts earlier

for biodiesel blends due to their higher density, leading to higher peak cylinder

temperature.

McDonald et al. [161] obtained the heat release from the actual pressure angle

diagram with soya bean oil methyl ester as a fuel in an indirect injection diesel

engine and concluded that the overall combustion characteristics were quite similar

to diesel operation except shorter ignition delay for soya bean methyl ester.

Niehaus and Carroll [162] found that thermally decomposed soybean oil produced

slightly less power than diesel fuel and also produced low levels of hydrocarbons

and NOX emissions. The heat release rate was lowered with thermally cracked

soybean oil as compared to diesel. They suggested that by advancing the injection

timing, combustion temperatures can be increased and a higher maximum rate of

cylinder pressure rise and higher levels of premixed burning with the oil can be

achieved.

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Bari et al. [163] observed that crude palm oil had a 6% higher peak pressure than

diesel. They also observed that crude palm oil had a 2.6CA shorter ignition delay,

but lower maximum heat release rate compared with diesel. Chemical reactions,

such as cracking of the double bonds of the carbon chain, could have produced lightvolatile compounds which result in a shorter ignition delay as compared with diesel.

Due to the shorter ignition delay, less fuel was injected during the delay period

resulting in lower maximum heat release rates. This also resulted in less intense

premixed combustion, and usually translates into lower tendency to knock. Crude

palm oil had a longer combustion period than diesel. This is due to the fact that

another chemical reaction, polymerization of vegetable oil at higher temperatures

could have produced heavy low-volatile compounds. These heavy compounds aredifficult to combust and could not completely burn in the main combustion phase,

and subsequently continued to burn in the late combustion phase.

2.6 DUAL FUEL OPERATION OF DIESEL ENGINE

In the dual fuel engine, two fuels are used simultaneously. The secondary fuel or

pilot fuel (diesel, biodiesel etc.) is used to initiate the combustion process with the

primary fuel that is usually gaseous or liquid fuels (methanol, ethanol, gasoline etc.)

in the fumigated form. In the compression ignition dual fuel engines, the pilot fuels

are injected in a normal manner after compression of the primary fuel air mixture.

Extensive experimental investigations were done by M. P. Poonia [164] to study the

effect of the pilot (diesel) fuel injection parameters, pilot fuel quantity, intake

temperature, exhaust gas recirculation and intake air throttle on combustion andperformance of dual fuel engine using LPG as primary fuel. The analysis of the

study suggested that at a low injector lift pressure (150 bars) resulted in severe

knock at high loads whereas at loads less than 80%, the improvement in brake

thermal efficiency up to 3% was obtained by reducing the injector pressure from

170 to 150 bars. The injection delay found in dual fuel mode was always longer

than diesel operation mode. The optimum performance was obtained at 20% load

and 50% throttle along with 40% load and 37.5% throttle closing.

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Some researchers [165, 166] did experiments by using CNG as a primary gaseous

fuel with diesel as pilot fuel.

Ramesh et al. [167] studied the dual fuel operation of karanja oil and its biodiesel

with LPG as the inducted fuel in compression ignition engine. Banapurmath et al.

[168, 169]conducted a series of experiments to obtain combustion characteristics of

a 4-stroke compression ignition engine operated on neem, rice bran, honge oil and

honge oil methyl ester when directly injected and dual fuelled with producer gas

induction.

Stanislaw Szwaja and Karol Rogalinski [170] presented the results of investigations

carried out with the combustion of hydrogen in a compression ignition dieselengine. Namasivayam et al. [171] conducted experimental investigations using

biodiesel, emulsified biodiesel anddimethyl ether as pilot fuels using natural gas as

primary fuel.

2.7 ECONOMIC FEASIBILITY OF BIODIESEL

The Biofuels market has been witnessing a continuous growth and developments

across the world over the past few years. Governments across the world are feeding

huge money and resources into the development of this sector in an attempt to

reduce their dependency on oil. The volatile oil prices and production levels have

further enlightened the need for continuous development in this sector. During

2001-2006 alone, the global annual production of biodiesel and ethanol grew by

43% and 23%, respectively. The major economic factor to consider for input costsof biodiesel production is the feedstock (price of seed, seed collection and oil

extraction, transport of seed and oil), which is about 7580% of the total operating

cost. Other important costs are labor, methanol and catalyst, which must be added to

the feedstock. Cost recovery will be through the sale of cake and of glycerol.

Economical feasibility of biodiesel depends on the price of the crude petroleum and

the cost of transporting diesel long distances to remote markets in India. It is certain

that the cost of crude petroleum is bound to increase due to increase in its demand

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and limited supply. Further, the strict regulations on the aromatics and sulphur

contents in diesel fuels will result in higher cost of production of diesel fuels as

removal of aromatics from the distillate fractions requires capital-intensive

processing equipments. India has rich and abundant forest resources with a widerange of plants and oilseeds. The production of these oilseeds can be stepped up

many folds if the government takes the decision to use them for producing

alternative fuels for diesel engines.

Palm oil and refined soya oil are the main option that is traded internationally. The

costs for biodiesel production from palm oil, soya oil and jatropha oil are estimated

about US$ 0.82/litre, US$ 0.70/litre and US$ 0.65/litre respectively. In India,

estimated current biodiesel finished production costs lies somewhere between Rs.

42 to 52 per litre [2, 172-174].

The Government of India also envisaged setting up of the National Biofuel Board to

develop a road map for the use of biofuels, besides taking appropriate policy

measures. In order to promote biodiesel and its production by providing necessary

support to the cultivators of jatropha, the Ministry of Petroleum and Natural Gas

announced the biodiesel Purchase Policy in October 2005. The policy provided for

the purchase of biodiesel at 20 specified purchase centers in 12 states at Rs. 25/litre

(inclusive of taxes and duties) from January 2006, moreover, the Government of

India fully exempted biodiesel from excise duties in the Union Budget of February

2007. The Indian government also announced, on 23rd December, 2009, attractive

incentives to encourage biofuels plantation in wastelands and to utilize indigenous

biomass feedstocks for the production of biofuels. It addresses the issues across the

entire value chain from plantations and processing to marketing of biofuels.Indias

newpolicy on biofuels targets blending at least 20% biofuels in diesel and petrol by

2017. This implies that 13.38 million tonnes of biodiesel will be required [175].

http://india.carbon-outlook.com/content/library/national-policy-biofuels-dec-2009http://india.carbon-outlook.com/content/library/national-policy-biofuels-dec-2009

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Sudha et al. [176] estimated the waste land availability and economical biomass

production potential in India. Augustus et al. [177] screened 22 plants at Western

Ghats (Tamil Nadu) in India as economical potential alternative crops for biodiesel.

Other scientists Mohibbe et al. [178] pointed out some selected plants, which have

great potential for biodiesel production in India. Giibitz et al. [179] and Kandpal et

al. [180] highlighted the potential of jatropha oil for fulfilling the future energy

needs. Barnwal et al. [181] have highlighted the economical production and

utilization of biodiesel in India. A detailed economic analysis of vegetable oil based

biofuels in Spain was made by Dorado et al. [182]. They identified that the price of

the feedstock was one of the most significant factors. Also, glycerol was found to be

a valuable by-product that could reduce the final manufacturing costs of the process

up to 6.5% depending on the raw feedstock used.

2.8 INTERNATIONAL SCENARIO OF

BIODIESEL

Global production of biofuels has been growing rapidly. Many countries around the

world are embarking on ambitious biofuel policies through renewable fuel standards

and economic incentives. As a result, both global biofuel demand and supply is

expected to grow very rapidly over the next two decades, provided policymakers

maintain their policy goals. While the motivation for this expansion is complex, the

most important rationale is to enhance national energy security. Due to the growing

demand for fossil fuels and their relatively limited supply, governments of many

energy-short countries are searching for any and all means to increase their energy

production. Total biofuel production expected to grow more than six-fold from 12

billion gallons in 2005 to 83 billion gallons in 2030. Market expansion will be led

by a more than doubling of the global market for bio-ethanol, with the biodiesel

market achieving even more rapid growth [2, 175, 183].

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The utilization of biodiesel is not new, since it has been used as a substitute for

mineral diesel since the early 20th century, but in small quantities. What is new is

that from 2005 onwards biodiesel production and use has increased significantly.

The world biodiesel industry is still in its infancy but devolving rapidly. Worldoutput of biodiesel production in 2007 is reached to 9.52 million tonnes, valued at

about US$ 7 billion. By 2011-12, total biodiesel production could be as high as 20

million tonnes [2, 3, 4, 175, 184]. Table [2.3] shows the biodiesel production of

various countries in million tonnes. High fuel prices and generous regulatory

support have given the sector healthy margins and relatively short investment

payback times. Only a small fraction of world biodiesel production is currently

exchanged internationally, but this may change in the future.

Country 06-07 07-08 08-09 09-10 10-11

European Union 4.85 MT 5.95 MT 7.49 MT 8.42 MT 9.55 MT

USA 1.13 MT 1.70 MT 2.69 MT 1.80 MT 2.10 MT

Argentina 0.05 MT 0.18 MT 0.74 MT 1.16 MT 1.60 MT

Brazil 0.06 MT 0.36 MT 1.03 MT 1.40 MT 2.00 MT

Other 1.03 MT 1.33 MT 2.37 MT 2.94 MT 3.91 MT

Total 7.12 MT 9.52 MT 14.32 MT 15.72 MT 19.16 MT

Table [2.3] Production of Biodiesel in Different Countries in Million Tonnes[2, 3, 4, 34, 175, 183-190]

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Owing to their availability, various oils have been in use in different countries as

feedstock for biodiesel production. The vegetable oils mainly used for biodiesel

production in Europe are rapeseed or sunflower oil, USA and Canada uses soya

bean, rapeseed, other waste oils and fats; frying oil and animal fats are the chosenoption in Ireland; castor oil and soya bean oil is used in Brazil; coconut oil is

preferred in Malaysia and Philippines; palm oil in Thailand, Malaysia, Indonesia

and the Philippines; cotton seed oil in Greece; linseed and olive oil in Spain;

jatropha and karanja are used in India, Nicaragua and Africa to produce biodiesel.

Several other plants such as neem (azadirachta indica), meswak (salvadora species),

mahua (madhuca indica), rubber (hevea species), castor (ricinus communis),

diploknema butracea, garcinia species and thumba (citrullus colocynthis) can alsobe used for producing biofuels in India [183-190]. Table [2.4] summarizes the

feedstock used to produce biodiesel in various countries.

Vegetable oil Country

Rapeseed France, USA, Canada

Sunflower Italy, Southern France, Italy, Spain

Soya Bean USA, Canada, Brazil, China

Castor Brazil, India

Palm Malaysia, Indonesia, Thailand, Philippines

Coconut Malaysia,Philippines

Linseed, Olive Spain

Cotton Seed Greece, Malaysia,Jatropha Nicaragua, India, Central America, Africa

Karanja, Mahua, Neem India

Canola Canada, European Countries

Used frying oils Australia, Ireland

Waste oils and animal fats USA, Canada,Japan, Ireland

Table [2.4] Feedstock Used to Produce Biodiesel in Various Countries [183-190]

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2.9 DEVELOPMENT OF BIODIESEL IN INDIA

Biofuels are going to play an extremely important role in meeting Indias energy

needs. India is not only a large importer of oil with the prospect of increased

imports in the future, but also has significant potential for production of biofuels in

the country. India actually has large areas of wasteland, which could be utilized for

the production of biofuels. India and many countries in the world are on the verge

of devising and implementing programme for production, conversion and use of

biofuels, it is essential to base these on the rapidly expanding knowledge that

already exists in this area. Adoption of biofuels programme has several socio-

economic impacts as it creates domestic jobs in plant construction, operation,

maintenance and support in the surrounding communities. Biodiesel and bio-ethanol

also help in improving the air quality with reduced automotive emissions, because

they undergo complete oxidation. The Indian government has taken a major

initiative for promoting biofuels, ethanol from sugar cane (molasses) and biodiesel

from plants such as jatropha, jojoba and karanja. For a country like India, biofuels,

especially biodiesel production promises a number of economic, environmental and

social benefits, such as large-scale employment generation, particularly in the rural

sector. The biodiesel programme will open up a large number of land-based

employment opportunities through the raising of plantations and their subsequent

maintenance, collection of seed, the processing of vegetable seeds into oil and

transesterification.

In India, the sources of biodiesel are non-edible oils. Due to its wider adaptability,

jatropha curcas (ratanjyot) is regarded as the major source of biodiesel. The other

sources of biodiesel in the country are pongamia pinnata (karanja or honge),

calophyllum inophyllum (nagchampa), hevca brasiliensis (rubber), thumba (citrullus

colocynthis) and other vegetable oils. To encourage the production and use of

biodiesel in India, the Government of India set up a committee for the development

of biofuels in July 2002 under the Planning Commission. Based on the

recommendations of the committee, the National Mission on Biodiesel was

launched in the country, which was proposed to be implemented in two phases over

nine years, that is, Phase I from 2003 to 2007 and Phase II from 2007 to 2012.

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Phase I was the demonstration and test phase. The primary aim of this phase was to

cultivate jatropha and similar plants in a total area of 0.4 Mha in various states of

the country. The Government of India provided the necessary funding for the

project. Phase II has been proposed to focus on a self-sustaining expansion of theprogramme, leading to the production of biodiesel required to meet the demand

during 2011-12. The committee projected that by the end of the Eleventh Plan

(2011-12), the demand for high speed diesel shall be 66.9 MT, requiring 13.38 MT

of biodiesel to meet the requirement of 20% blending of mineral oil-based diesel

with biodiesel. It is estimated that to meet the production of 13.38 MT of biodiesel,

about 11.2 Mha of land would be required for plantation [1, 2, 34, 175, 191].

The Indian biodiesel programme is at a nascent stage, and the supply of raw

materials is a limiting factor for the development of the biodiesel economy in our

country. In the present scenario, when most of the cultivable area has been occupied

by conventional or cultivated crops, plant species that can come up in degraded

lands under less favorable environmental conditions need to be promoted.

Cultivation of jatropha coupled with increasing seed collection efficiency will help

augment the production of oil and also help to generate income and employment

opportunities for the weaker sections of the society. It is necessary that all the

stakeholders in the biodiesel programme develop some know-how transfer

mechanism, which provides for the sharing of fundamental data on cultivation of

biodiesel feedstock plants and its exploitation, marketing strategies, capacity

development, and execution of the necessary predictive research. In the biodiesel

sector, India has taken the initial steps toward commercial production. The work

accomplished so far includes developing high-yielding varieties of jatropha,

initiating jatropha nurseries, setting up pilot-plants for biodiesel manufacture and

testing biodiesel in public transport locomotives and buses. India has embarked in

the largest scale jatropha plantations in the world, despite the many uncertainties

involved, particularly lack of commercial experience, low productivity and land

quality [175, 191, 192].

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2.10 SUMMERY OF LITERATURE SURVEY

The literature review suggests that the vegetable oils produced from numerous oils

and seed crops have high energy content and reasonably good fuel properties, but

they require processing to biodiesel for its safe use in compression ignition engines.

It is reported that because of high viscosity, the neat vegetable oils can lead to

thickening in cold climate, fuel flow problems, poor atomization and low efficiency.

The vegetable oils therefore need to be converted into biodiesel, which has

properties suitable for application in diesel engines. The available literature shows

that the transesterification process has been a most suitable and acceptable method

for biodiesel production. From the experiments and studies conducted by plenty of

scientists and researchers, it has been observed that the biodiesel mostly causes

reduction in engine power and torque, but some studies have reported higher engine

power than conventional diesel fuel. Most of the studies showed lower carbon

dioxide, carbon monoxide, hydrocarbons and smoke emissions with the biodiesel as

compared to mineral diesel with a slight increased in NOXemissions.

Although encouraging work has been carried out on performance, emissions and

combustion of biodiesel produced from vegetable oils like jatropha oil, karanja oil,

sunflower oil, soya oil etc., but it was observed from literature survey that limited

amount of work has been done to evaluate performance, emission characteristics

and combustion analysis of diesel engine with biodiesel produced from non-

traditional vegetable oils like thumba oil, neem oil etc. The literature review also

indicates that detailed study on evaluation of performance, exhaust emission and

combustion behavior of the biodiesel dual fuel engine with LPG gas induction and

biodiesel injection has been scantily reported. The present study is undertaken

because the prospect for vegetable oils and biodiesel is very promising in the short

term because of their availability and suitability as a diesel engine fuel.