A K Gupta Technology ConsultantInformation peresented here has been compiled using information available in published literature and my Lecture notes and publications

What are Biofuels ?y Biofuels are fuels derived from renewable

sources. such as: crops, biomass

Why biofuels ?y Security of supply y Reduced GHG emissions y Limited fossil fuels resources

Biofuels as alternative to transportation fuels must be: Economically competitive Environmentally acceptable Easily available In view of t ese requirements tri lyceri e (ve etable oils/animal fat) an t eir erivatives offer viable alternative for biofuels

The use of vegetable oils as fuel dates back to 1895 hen Dr Rudolf Diesel developed the first diesel engine to run on vegetable oil Depending upon the climate and soil conditions different Countries are looking for different vegetable oils for boifuels

Common vegetable oils for biofuelsVegetable Oil Rape seed Sunflower Soyabean Palm Linseed, Olive Cotton Jatropha curcas Used Frying Oils Other Waste oils & fats. Country France, US Italy, Southern France USA Malaysia Spain Greece Nicaragua, India Australia USA

FEEDSTOCKS IN INDIAN CONTEXT Edible oils are in short supply. Imported to meet the demand. Therefore, not available for biofuels For India non-edible oils obtained from plants which can be grown on waste/ semi arid lands are more suitable. Species can be selected based on the regional climatic conditions Most of the non-edible oils available in India contains high FFA (2-12%)

Possible raw materials for biofuelsNON EDIBLE VEGETABLE OILS e.g y Ratanjyot Jatropha curcas y Karanja Pongamia glabra y Mahua Madhuca indica y Pilu Salvadora oleoides y Sal Shorea robusta y Nahor Mesua ferra linn y Kamala Mallotus phillipines y Kokam Garcinia indica y Rubber Seed Hevea Brasilensis

Vegetable Oils and Fatsy Oils and fats are composed of molecules

called triglycerides.y Each triglyceride is composed of fatty

acid three long-chains fatty acids of 8-22 carbons attached to a glyceride backbone.

TYPICAL FATTY ACID COMPOSITION-COMMON OIL SOURCE ( ref. Kincs, 1985)Fatty acid Lauric Myristic Palmitic Stearic Oleic Linoleic Linolenic Soyabean Cottonseed Palm Lard Tallow Coconut

0.1 0.1 10.2 3.7 22.8 53.7 8.6

0.1 0.7 20.1 2.6 19.2 55.2 0.6

0.1 1.0 42.8 4.5 40.5 10.1 0.5

0.1 1.4 23.6 14.2 44.2 10.7 0.4

0.1 2.8 23.3 19.4 42.4 2.9 0.9

46.5 19.2 9.8 3.0 6.9 2.2 0.0

Can Vegetable Oils be used as diesel?

Limitation of straight vegetable as transportation fuels High viscosity (30 to 40 cst at 38o C Poor atomization Poor volatility( leads to more deposites) Thermal cracking in diesel engines. Poor oxidation stability (Due to high Iodine value, ). Polymerization in combustion chamber leading to deposits. Injection fouling by deposits Fuel line and filter clogging Polymerization of triglycerides in the lube oil Hence modification of vegetable oils or engine is necessary for efficient & trouble free engine operation.

Straight Vegetable Oil as a Diesel Fuely Some people have expressed interest in using straight

vegetable oil (SVO), or waste oils from cooking and other processes, as fuel. These oils seem to be appealing because they are obtainable from agricultural or industrial sources without intermediate processing. y SVO and other waste oils are generally not considered acceptable vehicle fuels for large-scale or long-term use.y

Performance of SVOy While straight vegetable oil or mixtures of SVO and

diesel fuel have been used by some over the years, research has shown that SVO has technical issues that pose barriers to widespread acceptance.y y The published engineering literature strongly indicates

that the use of SVO will lead to reduced engine life. This reduced engine life is caused by the buildup of carbon deposits inside the engine, as well as negative impacts of SVO on the engine lubricant.

Buildup of carbon deposit in engine as a function of oil in fuel

Performance of SVO boiling point effectsy Both carbon deposits and excessive buildup of SVO in

the lubricant are caused by the very high boiling point and viscosity of SVO relative to the re uired boiling range for diesel fuel. The carbon buildup doesn t necessarily happen uickly but instead over a longer period.

Performance of SVOy An SAE technical paper (No. 2003-01-0767.) published data on the use of SVO in engines. Quoting from this paper: y Compared to No. 2 diesel fuel, all of the vegetable oils are much more viscous, are much more reactive to oxygen, and have higher cloud point and pour point temperatures. y y Diesel engines ith vegetable oils offer acceptable engine performance and emissions for short-term operation. Long-term operation results in operational and durability problems.

Performance of SVOy Some investigators have explored modifying the

vehicle to preheat the SVO prior to injection into the engine. y Others have examined blends of vegetable oil ith conventional diesel.y y These techni ues may mitigate the problems to some

degree, but do not eliminate them entirely.

Performance of SVO viscosity effectsy Another issue that is particularly critical for use of

SVO is fuel viscosity. y The viscosity of pure SVO is much higher than that of diesel fuel at normal operating temperatures. y This can cause premature ear of fuel pumps and injectors and can also dramatically alter the structure of the fuel spray coming out of the injectors to increase droplet size, decrease spray angle.

SVO in modern diesel enginey The long-term effect of using SVO in modern diesel

engines that are e uipped ith catalytic converters or filter traps is also a matter of concern. y Buildup of fuel in the lubricant is more significant in these engines even for petroleum diesel and ould likely be severe ith SVO. y In general, these systems ere not originally designed ith SVO in mind and can be seriously damaged or poisoned by out-of-spec or contaminated fuel.

Temperature on the viscosity of SVO and diesel fuel

Transformation of vegetable oils to BiofuelsVegetable oils can be converted into biofuels by various physical and chemical transformations: y Pyrolysis y Micro-emulsification y Dilution with solvent y Transesterification y Thermo-catalytic conversion y Decarboxylation y Catalytic Hydrotreatment

Pyrolysis of vegetable oilsy Pyrolysis involves thermal decomposition of vegetable oils

to produce mixture of hydrocarbons (alkanes, alkenes, alkadienes, aromatics and carboxylic acids etc) y Catalysts ,largely metallic salts have also been used to obtain alkanes and olefins similar to those present in petro diesel y The composition of pyrolyzed oil depend upon the type of vegetable oil y The liquid fractions obtained via pyrolysis have composition close to petro-diesel

Typical characteristics of pyrolysed soya oily Contains 79% carbon and 12% hydrogen y Viscosity :

10.2 cst y Cetane No.: 43 y Acceptable levels of sulfur, water, and sediments y Acceptable copper corrosion Engine tests on pyrolysis oil has been limited to short duration tests

Micro-emulsificationy Micro-emulsion is an isotropic, clear, or transluscent thermodynamically stable dispersion of oil in water with surfactant and often a small amount of amphiphilic moleule called cosurfactant. y Micro-emulsion of vegetable oil can be made of :

- vegetable oil with an ester and a dispersant (cosolvent) or - vegetable oil with an alcohol and surfactant with or without diesel. y Methanol, ethanol or butanol can be used as alcohol y The use of 2-octanol as cosurfactant in triolein and soya bean oil has been demostrate (Bagby et al 1987)

Dilution of vegetable oily Dilution of vegetable oil can be done with diesel, a

solvent or ethanol y Various researchers have tested diluted vegetable oils (soya bean oil in diesel 1:3 ratio, in hydrocarbon solvent 1:1 ratio) diesel engines but could not recommend for long term use to due to problems like - severe engine nozzle coking and sticking, thickening of lube oil, carbon deposit on intake valves, corrosion and wear of top ring.

Transesterification of vegetable oilsy Transesterification of vegetable oils/ animal fats

with lower alcohols such as methanol or ethanol produces esters, commonly known as biodiesel, that are found suitable for use as fuel in diesel engines. y During the last decade conversion of vegetable oils to biodiesel has been an area research all over the globe.

Transesterification is a suitable way to convert oils and fats into biodiesel Lowering of - Viscosity - Boiling point - Flash point Increase of cetane number (10 to 20 units). Cleaner combustion / lower engine deposits.

TRANSESTERIFICATION OF VEGETABLE OILVegetable Oil (Triglyceride) CH2 OCOR CH OCOR CH2 OCOR + 3CH3OH 3RCOOCH3 + Methanol / ethanol Esters + Glycerine

CH2OH CH OH CH2OH

R REPRESENTS HYDROCARBON CHAINS OTHER REACTIONS Fatty Acids RCOOH Methanol CH3OH Ester RCOOCH3 + Water H2O

+

WHAT IS BIODIESEL?Biodiesel is a renewable fuel. Technically biodiesel is vegetable oil methyl / ethyl ester. The biodiesel molecules are very simple hydrocarbons containing no sulfur, ring molecules or aromatics associated with fossil fuels.

TECHNICAL ADVANTAGES Very low sulphur content. No Aromatics No net carbon dioxide addition to

environment. 99.6% bio-degradability within 21 days Renewable Source.

DISADVANTAGESModification in FI Lower energy content (5-7%less than distillate system for (5more/optimized fuel air fuel) mixture More deposit on engine components(olefins, traces of glycerides) Engine oil degradation Marginal NOx increase (1-6%) (1Use of additives

Use of improved engine oil Use of after treatment devices

Average change in HDDV mass emissions due to use of biodiesel relative to a standard diesel*Biodiesel fuel Emission type NOx PM CO VOC SO2 +2.4 % -8.9 % -13.1 % -17.9 % -20 % +13.2 % -55.3 % -42.7 % -63.2 % -100 % B20 B100

*Standard diesel has sulfur content of < 500 ppm

COMMERCIAL BIODIESEL TECHNOLOGIES Base catalysed transesterification with refined oils. Base catalysed transesterification with low fatty acid greases and fats. Acid esterification followed by transesterification of low or high free fatty acid fats and oils. Others under development include: Biocatalysed transesterification. Super critical methanol process Heterogeneous catalyst process( IIP, Axens) Transesterification is simple and easily adaptable at commercial scale. .

GENERAL PROCESS STEPS Alkali process Vegetable OilMethanol Mixing Catalyst (KOH/NaOH) Transesterification 1-3 stages

Glycerine Separation Crude Glycerine

Methanol Recovery

Biodiesel Purification Bio diesel

IIP heterogeneous catalyst processVegetable Oil

Alc + Cat.

Esterification & Transesterification

Crude glycerine Alcohol recovery Glycerine refining

Crude Biodiesel

Refining

Catalyst

Biodiesel Glycerine

APPROPRIATE TECHNOLOGY Must be able to process variety of vegetable oils without or minimum modifications. Must be able to process high free fatty containing oils/ feedstocks. Must be able to process raw both expelled and refined oils. Process should be environment friendly almost zero effluents. Able to produce marketable by products glycerine, fatty acids, soap if any. Must be able to produce fuel grade esters; Biodiesel produced should meet the standard specifications. The process should be adaptable over a large range of production capacities.

Comparision of biodiesel processesProcesses Reaction temp 0C FFA in raw material Water in raw material Alkali 6060-70 Lipase 3030-40 Acid 5555-80 Ester Supercritical alcohol 230230-290 Ester Heterogeneous catalyst 150150-300 Ester No/little influence Higher High easy Distillation/ washing Medium negligible Very good

Saponified Methyl product ester Interfere with reaction Normal Difficult Repeated washing Cheap High Poor No influence Higher Easy None

Interfere No influence with reaction Normal Difficult Higher High easy

Yield methyl ester Recovery of glycerin Purification of ester

Repeat Distillation/ ed washing washing Cheap High Poor Medium Negligible Good

Cost of catalyst Effluent generation Crude glycerin quality

Expensive Low Good

Catalytic Hydrotretmenty Vegetable oil can be converted to biofuel via

catalytic hydrotreatment similar to hydroprocessing process in a petroleum refinery.

UOP/Eni Processy UOP and Eni developed a process to produce green

diesel from vegetable oils y The process utilises catalytic saturation, hydrodeoxygenation, decarboxylation, and hydroisomerization reactions to produce isoparaffin-rich diesel fuel from vegetable oils and fatty acids. y The resultant biofuel has high cetane value, lower gravity, good cold flow properties, and excellent storage stability. y The process well integrates with existing petroleum refinery

UOP/Eni Process

Chemistry of the process:

Triglycerides + H2 ====> Catalyst

Paraffin + H2O/COx

UOP/Eni Process

UOP/Eni Process Process yields

UOP/Eni Process

UOP/Eni Process Green diesel fuel properties

Decaboxylationy Catalytic Decarboxylation of fatty acids produces n-

alkanes y If the feed stock is vegetable oil products such as gasoline, diesel can be produced. y Diversified Energy Corporation (DEC) and NC State University (NCSU) are developing technology for converting oils derived from any lipidic compound (like agriculture crops, animal fats, algae, energy crops, etc.) to high-value fuels. y The technology is termed Centia

DEC and NCSU Process, Centiay Centia , integrates a sequence of three thermal-

pressurized-catalytic processes

Decarboxylation process for biofuels

DEC and NCSU Process, Centiay Centia has been specifically tailored to produce a

.

fuelthat is jet-fuel compliant y Beyond aviation fuel, because Centia produces nalkanes (a building block of fuels) from Step #2, these nalkanes can be reformed differently to create a number of other petroleum-like biofuels. y As one example, by varying the catalyst, temperature, pressure, and kinetics of Step #3, the n-alkanes could be reformed to produce bio-gasoline

Conclusionsy Vegetable oils are excellent feed stocks for producing

biofuels. Their non-availability in large quantities is the major hurdle. y Straight vegetable oils are not suitable in long run y Emulsification and dilution with solvent are currently available technologies for using straight vegetable oil as fuel. More research is needed to overcome the associated problems -carbon deposit, storage stability and corrosion in particular.

Conclusionsy Decarboxilation and hydrotreatment processes produce

hydrocarbons as product which is more compitable with petro-fuels. However, these are suitable for large scale plants. y Biodiesel has high lubricity thus more suitable for blending in ultra low sulfur diesel.It can be produced at small to large capacities. y There is a need to improve the transesterification / esterification technology to include various quality vegetable oils including waste oils