Biodiesel final

8/7/2019 Biodiesel final

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Biodiesel


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Definition of Biodiesel

Biodiesel refers to a vegetable oil - or animal fat-

based diesel fuel consisting of long

chain alkyl esters. Biodiesel is typically made by

chemically reacting lipids (e.g., vegetable oil,

animal fat (tallow)) with an alcohol. designated

B 100.

Biodiesel must meet the specifications of ASTMD 6751


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Blends of Biodiesel

Blends of biodiesel and conventional hydrocarbon-baseddiesel are products most commonly distributed for use inthe retail diesel fuel marketplace. Much of the world uses asystem known as the "B" factor to state the amount of

biodiesel in any fuel mix

100% biodiesel is referred to as B100, while

20% biodiesel, 80% petrodiesel is labeled B20




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Biodiesel Production Processes

Definition and standards

Transesterification

Fatty acid chains

Standard recipes.


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Transesterification

O O

|| ||

CH2 - O - C - R1 CH3 - O - C - R1|| O O CH2 - OH

| || || |CH - O - C - R2 + 3 CH3OH => CH3 - O - C - R2 + CH - OH

| (KOH) || O O CH2 - OH

| || ||CH2 - O - C - R3 CH3 - O - C - R3

Triglyceride methanol mixture of fatty esters glycerin


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Triglyceride Sources

endered animal fats: beef tallow, lard

Vegetable oils: soya bean, canola, palm, etc.

hicken fat endered greases: yellow grease (multiple

sources)

ecovered materials: brown grease, soapstock,

etc.


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Standard ecipe

100 lb oil + 21.71 lb methanol

100.45 lb biodiesel + 10.40 lb glycerol

+ 10.86 lb XS methanol

Plus 1 lb of Na catalyst


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Competing eactions

Free fatty acids are a potential contaminant

of oils and fats.

O||

HO -C -

Carboxylic Aci (R is a carbon chain)

- - ( 2) ( 2)

Oleic Aci


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+ KOH

Oleic Acid Potassium Hydroxide

O||

K+ -O - C - (CH2)7 CH=CH(CH2)7CH3 H2O

Potassium oleate (soap) Water

Fatty acids react with alkali

catalyst to form soap.

O

HO C (CH2)7CH=CH(CH2)7CH3


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Elimination of Water

Water hydrolyzes fats to form free fatty acids,

which then form soap.

O

CH2 - O - C - 1 CH3 - OH

O O O

CH - O - C - 2 H2O CH3 - O - C - 2 HO - C- 1

O O

CH2 - O - C - 3 CH3 - O - C - 3

Triglyceride Water Diglyceride Fatty acid


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Soap

Soaps can gel at ambient temperature

causing the entire product mixture to form a

semi-solid mass. Soaps can cause problems with glycerol

separation and washing.


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Process Issues

Feedstock requirements

eaction time

Continuous vs.. batch processing

Processing low quality feedstocks


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Feedstocks Used in Biodiesel

Production Triglyceride or fats and oils (e.g. 100 kg soybean

oil) vegetable oils, animal fats, greases,soapstock, etc.

Primary alcohol (e.g. 10 kg methanol) methanolor ethanol (44% more ethanol is required forreaction)

Catalyst (e.g. 0.31.0 kg sodium hydroxide)

Neutralizer (e.g. 0.25 kg sulphuric or hydrochloricacid)


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Reaction time

Transesterification reaction will proceed atambient (70F) temperatures but needs 4-8 hoursto reach completion.

Reaction time can be shortened to 2-4 hours at105F and 1-2 hours at 140F.

Higher temperatures will decrease reaction timesbut require pressure vessels because methanol

boils at 148F (65C). High shear mixing and use of cosolvents have

been proposed to accelerate reaction.


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Batch vs. Continuous Flow

Batch is better suited to smaller plants (


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Developi g Process p

tio s

Schemes for accelerating the reaction

Supercritical methanol

High shear mixing Cosolvents (Biox)

Solid (heterogeneous) catalysts

Catalyst reuse Easier glycerol clean-up


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Curre t esearc Using the current yields, vast amounts of land and fresh

water would be needed to produce enough oil tocompletely replace fossil fuel usage.

It would require twice the land area of the US to bedevoted to soybean production, or two-thirds to be devotedto rapeseed production, to meet current US heating andtransportation needs alones.

Specially bred mustard varieties can produce reasonablyhigh oil yields and are very useful in crop rotation withcereals, and have the added benefit that the meal leftoverafter the oil has been pressed out can act as an effectiveand biodegradable pesticide.

A group of Spanish developers working for a companycalled Ecofasa announced a new biofuel made from trash.The fuel is created from general urban waste which istreated by bacteria to produce fatty acids, which can beused to make biodiesel.


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Algal biodiesel A self-published article by Michael Briggs, at

the UNH Biodiesel Group, offers estimates for the realisticreplacement of all vehicular fuel with biodiesel by utilizingalgae that have a natural oil content greater than 50%.

Briggs suggests algae should be grown on ponds at wastewatertreatment plants. This oil-rich algae can then be extracted from

the system and processed into biodiesel, with the driedremainder further reprocessed to create ethanol.

The feasibility studies for the production of algae to harvest oilfor biodiesel have been conducted to arrive at the above yieldestimate.

Algaculture unlike crop-based biofuels does not entail adecrease in food production, since it requiresneither farmland nor fresh water.


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Biodiesel by FungiA group of scientists at the Russian Academy of

Sciences in Moscow stated that they had isolatedlarge amounts of lipids from single-celled fungi andturned it into biodiesel in an economically efficientmanner.This fungal species ;Cunninghamella japonica.

The recent discovery of a variant of thefungus Gliocladium roseum points toward the

production of so-called myco-diesel from cellulose.

It was discovered in the rainforests of

northern Patagonia and has the unique capability ofconverting cellulose into medium lengthhydrocarbons typically found in diesel fuel.


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Second generation microalgal systems are increasingly

predicted by international experts and policy makers toplay a crucial role in a clean environmentally sustainablefuture as they have important advantages.

Most significantly, these achieve a higher yield per hectare (potentially over 15-fold higher than oil palm, the

biggest current oil producer; and their ability to becultivated on non-arable land, thereby reducing thecompetition with food crops.

Algal production systems are recognized as among the

most efficient means of producing biomass for fuel andfurther improvements are likely to occur in the near future. For e.g. algae are already being engineered forincreased photosynthetic efficiency of the overall culturedue to improved light penetration and reduced

fluorescence and heat losses

Micro Algae


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Apart from high efficiency production of oil for

biodiesel, microalgae are also well suited for theproduction of feedstocks for other biofuels. Thedevelopment of the technologies for high efficiencyalgal biodiesel production is also applicable to biohydrogen, biogas, bioethanol and biomass-to-liquid

(BTL) approaches using fast growing algae. BTL, biohydrogen and biomethane processes are discussed

below as they are especially pertinent to microalgalsystem. Bio ethanol is not described as the processes

used for its production with microalgae as feedstocksare very similar to established 1st generationtechnologies that use corn- and sugarcane-derived feedstocks.


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Summary

Biodiesel is an alternative fuel for dieselengines that can be made from virtually anyoil or fat feedstock.

The technology choice is a function ofdesired capacity, feedstock type and quality,alcohol recovery, and catalyst recovery.

Maintaining product quality is essential forthe growth of the biodiesel industry.


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Documents

Biodiesel final