07/29/2010 (4:52 am)
BIODIESEL - viability Best answer on the web
the viability of its production and use as an alternative fuel within
the transport industry.
Is it worth the investment for vehicle manufacturers?
The impact on the environment, the environmental cost and benifits of
biodiesel against diesel.
Manufacturers engine warranties on diesel vehicles - regarding the use
of biodiesel in their diesel engines. Is the warranty affected if you
use biodiesel instead of diesel?
The affect on the rural economy e.g. agriculture and the increased
demand for oil producing crops such as oil seed rape.
The economic affect of biodiesel - cost, break even price, after tax
return, total capital cost, total biodiesl cost.
Government incentives for the use of biodiesel. (I am already familiar
with the degredation)are there any others?
http://scholar.google.com/scholar?hl=en&lr=&q=biodiesel+transport
Synthetic Biology (Gene Hacking, Biosensors, Biological computing)
Biologically Active Artificial Enzyme Created
http://dukemednews.duke.edu/news/article.php?id=7669
http://www.sciam.com/article.cfm?articleID=0009FCA4-1A8F-1085-94F483414B7F0000&pageNumber=5&catID=2 Synthetic Life
Many cars in Europe are multi-fuel capable because fuel availability changes from region to region. Apparently there are a few manufacturers that have made claim that they are "Biodiesel" friendly.
http://journeytoforever.org/biodiesel_vehicle.html
>>>The impact on the environment, the environmental cost and benifits of
>>>biodiesel against diesel.
There again, since Biodiesel uses already 'waste' oils, the environmental impacts have already been paid for through refining (the oil refining process is complex but simplistically, you cook crude oil at different temperatures and pressures to create one kind which produces another kind of oil as waste which is then refined again to a different grade of fuel all down the chain till you get rotgut diesel).
As for air polution, studies have been done with B20 type Biodiesel and concludes that there is a 4-6% decrease in emissions over regular diesel. B20 is a mixture of petro-diesel and bio-diesel however running more bio-diesel should reduce it slightly more.
http://www.nrel.gov/docs/fy03osti/33793.pdf
>>>Manufacturers engine warranties on diesel vehicles - regarding the use
>>>of biodiesel in their diesel engines. Is the warranty affected if you
>>>use biodiesel instead of diesel?
Apparently BioDiesel cleans your engine prettier than petro-diesel however people have reported that they have to replace fuel lines due to leaks (I would suspect because of the petrochemical make up of regular diesel and the rubber having petro-chemical substances that keep each other from rotting away.
Additionally, with colder weather, Biodiesel has a lower gelling point than petro-diesel. Additives or mixed gas can remedy this along with aftermarket heaters.
(personally I'm holding out for pure hydrogen or fuel cell driven cars)
>>>The affect on the rural economy e.g. agriculture and the increased
>>>demand for oil producing crops such as oil seed rape.
There are some reports on how it "could" improve the environment. Then again they already grow Soy and Corn that can be turned into fuel. Will it improve it? Possibly since ADM can genetically engineer faster crops now-a-days it would be perfect. Will it change the commodies market in the near-term? Not until it is utilized at a larger scale. (A biofuel/electric hybrid would change all that. Any takers Honda or Toyota? ;) While your at it, see above! I wanna drink my emissions...
>>>The economic affect of biodiesel - cost, break even price, after tax
>>>return, total capital cost, total biodiesl cost.
Depends on where you obtain your fuel at the moment. If you have a local retailer that sells biodiesel by the tank, sure. If you have access to a McDonalds who pays Waste Management to lug off their fryer grease, then you'd be paying them instead of the otherway around. Of course then you'd have to still homebrew the fuel but isn't that the fun of experimentation? Lay down the joint, hippy. ;)
>>>Government incentives for the use of biodiesel. (I am already familiar
>>>with the degredation)are there any others?
There are incentives in some states for zero-emissions like California. However the other flip side to it is that we pay a Fuel Tax on every gallon of gas we pump that goes into the Federal Highway Tax Fund which builds our highways and interstates. That being said, if everyone starts brewing their own fuel, the roads are gonna look shabby pretty quick. Eventually there will be something else to replace this tax with something else (maybe tires will have added taxes... wonderful, if spending 300/wheel isn't bad enough, forking out a grand a tire will really irk me.)
Mental note: get pilots license sooner or develop hovervehicle.
----------------------------------Economic Facts---------------------------------------
**This is a very comprehensive list of articles and studies relating to biodiesel and its economic implications. http://www.biodiesel.org/resources/reportsdatabase/viewall.asp?PageNo=1&SortCol=filename
**The United States may not have the arable land space to fully transition to biodiesel
(http://www.tve.org/ho/doc.cfm?aid=1433&lang=English
"Some nations and regions that have pondered transitioning fully to biofuels have found that doing so would require immense tracts of land if traditional crops are used. Considering only traditional plants and analyzing the amount of biodiesel that can be produced per acre of cultivated land, some have concluded that it is likely that the United States, with one of the highest per capita energy demands of any country, does not have enough arable land to fuel all of the nation's vehicles. Other developed and developing nations may be in better situations, although many regions cannot afford to divert land away from food production. For third world countries, biodiesel sources that use marginal land could make more sense, e.g. honge nuts grown along roads."
**However, recent studies show that it may only take 0.3% of the land area of the US to fully transition in transportation fuel.
http://www.unh.edu/p2/biodiesel/article_alge.html
"More recent studies using a species of algae that has oil contents of as high as 50% have concluded that as little as 28,000 km? or 0.3% of the land area of the US could be utilized to produce enough biodiesel to replace all transportation fuel the country currently utilizes. Further encouragement comes from the fact that the land that could be most effective in growing the algae is desert land with high solar irradiation, but lower economic value for other uses and that the algae could utilize farm waste and excess CO2 from factories to help speed the growth of the algae.
**The energy yield ration is somewhat less than with diesel fuel. Meaning it may cost more to produce.
http://en.wikipedia.org/wiki/Biodiesel
"Additional factors must be taken into account, such as: the fuel equivalent of the energy required for processing, the yield of fuel from raw oil, the return on cultivating food, and the relative cost of biodiesel versus petrodiesel. A 1998 joint study by the U.S. Department of Energy (DOE) and the U.S. Department of Agriculture (USDA) traced many of the various costs involved in the production of biodiesel and found that overall, it yields 3.2 units of fuel product energy for every unit of fossil fuel energy consumed.
That measure is referred to as the energy yield. A comparison to petroleum diesel, petroleum gasoline and bioethanol using the USDA numbers can be found at the Minnesota Department of Agriculture website (http://www.mda.state.mn.us/ethanol/balance.html). In the comparison petroleum diesel fuel is found to have a 0.843 energy yield, along with 0.805 for petroleum gasoline, and 1.34 for bioethanol. The 1998 study used soybean oil primarily as the base oil to calculate the energy yields. It is conceivable that higher oil yielding crops could increase the energy yield of biodiesel." (http://www.gobluesun.com/html/pdf/Biodiesel_Lifecycle.pdf)
**Economic Analysis of Alternative Indiana State Legislation on Biodiesel
http://www.agecon.purdue.edu/cab/research/articles/biodiesel.pdf
**Additional facts:
http://www.agriculture.state.ia.us/biodiesel.html
*One bushel of soybeans can produce 1.4 gallons of biodiesel.
* Since June 1999, biodiesel sales have grown to an industry estimate of 15 million gallons, or the equivalent of ten million bushels of U.S. soybeans.
* A study completed in 2001 by the U.S. Department of Agriculture?s Office of Energy Policy and New Uses in conjunction with the Economic Research Services (ERS) found that an average annual increase of the equivalent of 200 million gallons of soy-based biodiesel demand would boost total crop cash receipts by $5.2 billion cumulatively by 2010, resulting in an average net farm income increase of $300 million per year.
* In the last year, the price of wholesale delivered biodiesel has decreased significantly. Generally, a 20% biodiesel blend (with 80% regular diesel, known as B20) costs about 15-30 cents more per gallon than straight petroleum fuel. B2 blends generally cost only a couple of cents more than No. 2 diesel fuel."
----------------------------Effects on the Rural Economy--------------------------
Effects on the Farm Economy of a Renewable Fuels Standard for Motor Vehicle Fuel
http://www.biodiesel.org/resources/reportsdatabase/reports/gen/20020826_gen335.pdf
Biodiesel's Potential Impact to Farmers
http://www.biodiesel.org/resources/reportsdatabase/reports/gen/19990901_gen-194.pdf
CULTIVATING A NEW RURAL ECONOMY
http://www.eesi.org/publications/Newsletters/ECO/BCO%2024.htm
Biodiesel: Potential and Possibilities for the Arkansas Economy
www.1800arkansas.com/energy/ files/biodiesel/MARK%20COCHRAN.ppt
Local Biodiesel News
http://www.thesoydailyclub.com/revupthatsoyfuel/biodieselbulletin03292002.asp
-----------------------------Market Data----------------------------------------------------
**The U.S. market is expected to grow drastically and prices have been declining.
http://en.wikipedia.org/wiki/Biodiesel
"U.S. market is expected to grow to 1 or 2 billion US gallons (4,000,000 to 8,000,000 m?) by 2010. The price of biodiesel has come down from an average $3.50 per US gallon ($0.92/l) in 1997 to $1.85 per US gallon ($0.49/l) in 2002. However this is still higher than petrodiesel which averaged about $0.85 per US gallon ($0.22/l) in 2002 before road tax is added."
CO2 Mitigation through Biofuels in the Transport Sector - Status and Perspectives
http://www.biodiesel.org/resources/reportsdatabase/reports/gen/20040801_gen-351.pdf
**Government incentives are driving the market
http://www.mdac.state.ms.us/Library/AlternativeEnergy/B_Fuelmarket.html
"According to the American Biofuels Association, with government incentives comparable to those provided for ethanol, biodiesel sales could reach about 2 billion gallons per year, or about 8% of highway diesel consumption. At this level of market penetration, biodiesel would probably be used in bus fleets and heavy-duty trucks (primarily in blends with fossil diesel at the 20% level), marine vessels such as ferries, construction and agricultural vehicles, home heating oil systems, and electric generation. Small quantities of biodiesel in low-sulfur diesel fuels could be used to offset the removal of sulfur (sulfur lubricates diesel fuel engine components)."
**Current Costs
http://www.mdac.state.ms.us/Library/AlternativeEnergy/B_Fuelmarket.html
"Biodiesel currently costs between $1 and $2 per gallon and could compete with low-sulfur diesel fuels. Feedstock costs account for a large percent of direct production costs, including capital cost and return. It takes about 7.3 pounds of soybean oil, which costs about 20 cents per pound, to produce a gallon of biodiesel. Feedstock costs alone, therefore, are at least $1.50 per gallon of soy biodiesel. Fats and greases cost less and produce less expensive biodiesel, sometimes as low as $1.00 per gallon. The quality of the fuel is similar to soy biodiesel fuel, and sophisticated feedstock blending strategies will begin to address consumer requests for low NOx fuels in the summer time and good cold flow fuels in the winter time."
**Some Government fleets are using Biodiesel
http://www.mdac.state.ms.us/Library/AlternativeEnergy/B_Fuelmarket.html
"The use of biodiesel has grown dramatically during the last few years. The Energy Policy Act was amended in 1998 to include biodiesel fuel use as a way for federal, state, and public utility fleets to meet requirements for using alternative fuels."
**There may not be enough sources of biodiesel to fully transition to it as a main source
http://en.wikipedia.org/wiki/Biodiesel
"Many advocates suggest that waste vegetable oil is the best source of oil to produce biodiesel. However, the available supply is drastically less than the amount of petroleum-based fuel that is burned for transportation and home heating in the world. According to the United States Environmental Protection Agency (EPA), restaurants in the US produce about 3 million gallons of waste cooking oil annually. Although it is economically profitable to use WVO to produce biodiesel, it is even more profitable to convert WVO into other products such as soap. Hence, most WVO that is not dumped into landfills is used for these other purposes. Animal fats are similarly limited in supply, and it would not be efficient to raise animals simply for their fat. However, producing biodiesel with animal fat that would have otherwise been discarded could replace a small percentage of petroleum diesel usage."
**Plant derivitives may allow for sustainable use of biodiesel on the mass market.
http://en.wikipedia.org/wiki/Biodiesel
"The estimated transportation fuel and home heating oil use in the United States is about 230,000 million gallons. (Briggs, 2004) Waste vegetable oil and animal fats would not be enough to meet this demand. In the United States, estimated production of vegetable oil for all uses is about 33,000 million pounds (15,000,000 t) or 4,500 million US gallons (17,000,000 m?)), and estimated production of animal fat is 12,000 million pounds (5,000,000 t). (Van Gerpen, 2004)
For a truly renewable source of oil, crops or other similar cultivatable sources would have to be considered. Plants utilize photosynthesis to convert solar energy into chemical energy. It is this chemical energy that biodiesel stores and is released when it is burned. Therefore plants can offer a sustainable oil source for biodiesel production. Different plants produce usable oil at different rates. Some studies have shown the following annual production:"
**Mustard may provide a large yield of sustainable biodiesel
http://en.wikipedia.org/wiki/Biodiesel
"The production of algae to harvest oil for biodiesel has not been undertaken on a commercial scale, but working feasibility studies have been conducted to arrive at the above number. Specially bred mustard varieties can produce reasonably high oil yields, and have the added benefit that the meal leftover after the oil has been pressed out can act as a effective and biodegradable pesticide. There is ongoing research into finding more suitable crops and improving oil yield. Using the current yields, vast amounts of land would have to be put into production to produce enough oil to completely replace fossil fuel usage."
-----------------------------------Environment Facts------------------------------------
*Biodiesel is a renewable, biodegradable, cleaner-burning fuel. Unlike other fuel additives, biodiesel poses minimal risk to water quality.
* A 100% biodiesel blend lowers carbon monoxide (CO) emissions by 44 percent, particulate matter emissions by 40 percent and sulfate emissions by 100 percent.
* B20 lowers carbon monoxide (CO) emissions by 9 percent, particulate matter emissions by 8 percent and sulfate emissions by 20 percent. When B20 is used along with an oxidation catalyst, it reduces particulate matter by 45 percent, carbon monoxide by 41 percent and total hydrocarbons by 65 percent.
* The ozone forming potential of the speciated hydrocarbon emissions for biodiesel was nearly 50 percent less than that measured for diesel fuel.
* Biodiesel reduces air toxins by up to 90 percent.
* Biodiesel has the highest energy balance of any fuel. For every one unit of fossil energy needed to produce biodiesel, 3.2 units of energy are gained.
* Does not contribute to sulfur dioxide emissions"
http://www.agriculture.state.ia.us/biodiesel.html
**Biodiesel burns relatively clean
http://www.mdac.state.ms.us/Library/AlternativeEnergy/B_EnvironmentalBenefits.html
"Biodiesel is a renewable, biodegradable, cleaner-burning fuel. Unlike other fuel additives, biodiesel poses minimal risk to water quality.
A 100% biodiesel blend lowers carbon monoxide (CO) emissions by 44"
**Emissions data
http://biodiesel.org/pdf_files/emissions.PDF
------------------------------------------Performance-----------------------------------
**Manufacturer Warranties do cover biodiesel fuel. Using it won't void the warranty. http://www.agriculture.state.ia.us/biodiesel.html
"Manufacturer warranties cover defects in material and workmanship, and those warranties extend to engines burning biodiesel. Using biodiesel will not void warranties."
Biodiesel is compatible with diesel engines and does not void warranties.
http://www.mdac.state.ms.us/Library/AlternativeEnergy/B_Preformance.html
"Biodiesel can be operated in any diesel engine with little or no modification to the engine or the fuel system. In blends over 20%, biodiesel has a solvent effect, which may release deposits accumulated on tank walls and pipes from previous diesel fuel. The release of deposits may clog filters initially and precautions should be taken.
Manufacturer warranties cover defects in material and workmanship, and those warranties extend to engines burning biodiesel. Using biodiesel will not void warranties."
**Energy Content
http://www.agriculture.state.ia.us/biodiesel.html
"*Biodiesel has the highest energy content (BTUs) of any alternative fuel and is comparable to No. 1 diesel.
* Fuel efficiency is the same as diesel fuelFuel economy, power, and torque are similar to No. 2 diesel and vary linearly with the blend level."
**Life-cycle assessment of biodiesel versus petroleum diesel fuel
(Study)
http://ieeexplore.ieee.org/xpl/abs_free.jsp?arNumber=553557
**Empirically, biodiesel has been an efficient fuel source in the transportation industry
http://www.mdac.state.ms.us/Library/AlternativeEnergy/B_Preformance.html
"More than 100 major fleets use biodiesel. Additionally, numerous biodiesel demonstrations, including three one-million-mile tests and more than thirty 50,000-mile tests, have logged more than 10 million road miles with biodiesel blends. In these tests, performance, fuel mileage and drivability with biodiesel blends were similar to conventional diesel, but opacity levels were reduced and exhaust odor was less offensive. No adverse durability or engine wear problems were noted."
**Biodiesel performs similarly to diesel, is safer and effectively lubricates to reduce engine wear.
http://www.mdac.state.ms.us/Library/AlternativeEnergy/B_Preformance.html
"Biodiesel has the highest energy content (120,000 BTUs per gallon) of any alternative fuel
Biodiesel has significantly improved lubricity, which can decrease maintenance costs and reduce engine wear.
A flash point of over 300 F makes it much safer to use, store and handle than diesel, gasoline, or other gaseous fuels."
**Additional Performance Facts
"*Biodiesel has the highest energy content (120,000 BTUs per gallon) of any alternative fuel * Biodiesel has significantly improved lubricity, which can decrease maintenance costs and reduce engine wear. * A flash point of over 300 F makes it much safer to use, store and handle than diesel, gasoline, or other gaseous fuels. * More than 100 major fleets use biodiesel. Additionally, numerous biodiesel demonstrations, including three one-million-mile tests and more than thirty 50,000-mile tests, have logged more than 10 million road miles with biodiesel blends. In these tests, performance, fuel mileage and drivability with biodiesel blends were similar to conventional diesel, but opacity levels were reduced and exhaust odor was less offensive. No adverse durability or engine wear problems were noted. * Biodiesel can be operated in any diesel engine with little or no modification to the engine or the fuel system. In blends over 20%, biodiesel has a solvent effect, which may release deposits accumulated on tank walls and pipes from previous diesel fuel. The release of deposits may clog filters initially and precautions should be taken." http://www.agriculture.state.ia.us/biodiesel.html
_____________________________________________________
References:
Biodiesel Production Process
http://www.mdac.state.ms.us/Library/AlternativeEnergy/Biodiesel%20prod_quality.pdf
A look back at the U.S. Department of Energy Aquatic Species program: Biodiesel from Algae, July 1998, J. Sheehan, et. al. NREL (326pp pdf file) http://www.eere.energy.gov/biomass/pdfs/biodiesel_from_algae.pdf
An Overview of Biodiesel and Petroleum Diesel Lifecycles, May 1998, Sheehan, et. al. NREL (60pp pdf file) http://www.nrel.gov/docs/legosti/fy98/24772.pdf
Business Management for Biodiesel Producers, January 2004, Jon Von Gerpen, Iowa State University under contract with the National Renewable Energy Laboratory (NREL) (210pp pdf file) http://www.nrel.gov/docs/fy04osti/36242.pdf
Energy balances in the growth of oilseed rape for biodiesel and of wheat for bioethanol http://www.biodiesel.co.uk/levington.htm
Life Cycle Inventory of Biodiesel and Petroleum Diesel for Use in an Urban Bus, 1998, Sheehan, et. al. NREL (314pp pdf file) http://www.nrel.gov/docs/legosti/fy98/24089.pdf
Widescale Biodiesel Production from Algae
http://www.unh.edu/p2/biodiesel/article_alge.html
------------------------------------------------------------------------------------------
Additional Links:
http://www.graingrowersinc.com/pittcountyhosp1.htm
http://www.biodiesel.org/
Interactive map of retail biodiesel fueling sites in the US
http://www.biodiesel.org/buyingbiodiesel/retailfuelingsites/default.shtm
http://www.biodieselnow.com/
US Department of Energy - Office of Energy Efficiency and Renewable Energy (EERE)
http://www.eere.energy.gov/biomass/
Canadian renewable fuels association
http://www.greenfuels.org/bioindex.html
http://www.journeytoforever.org/biodiesel.html
http://www.localb100.com/
http://www.green-trust.org/wiki/index.php?title=Biofuels
http://www.nrel.gov/ US National Renewable Energy Laboratory
http://www.unh.edu/p2/biodiesel/index.html UNH Biodiesel Group
Soy biodiesel
http://www.soya.be/soy-biodiesel.php
Biodiesel-powered 1986 Winnebago and 1971 Nissan 240Z
http://www.veggievan.org and http://www.veggiecar.com
Biodiesel Fuel Testing: B100 & ASTM D6751 Biodiesel Specifications
http://www.intertek-cb.com/newsitetest/news/biodiesel03102003.shtml
Alternative fuels index
http://www.energyinstitution.org/Alt%20Fuels%20Index%20free%20request.htm
* What is Biodiesel?
http://www.biofuel.be/whatisbiodiesel.html
A forum for biodiesel and grease cars
http://biodiesel.infopop.cc/eve/ubb.x
Bio-power, a Trade Association of local producers of biodiesel in the UK
http://www.bio-power.co.uk
-------------------------------------Search Strategy---------------------------------
Google Search Terms:
-"biodiesel facts"
-"biodiesel market"
-biodiesel and transportation and market
Google Scholar Search Terms:
-biodiesel and transportation
I hope this helps. Please let me know if you require any clarification of my response. Good luck!
-adilroen-ga
Steve
The worlds first Biodiesel standard was the ONORM C1190 and was introduced in Februray 1991. In Europe today, we use the Euro Standard EN14214. While this standard may be new, Foglia et al (36) tell us that this is not a recent discovery. As early as 1900, the idea of using biodiesel as a substitute of mineral based fuel was put forward by Rudolph Diesel himself. Since this time, animal and vegetable oils have been widely tested as such a fuel alternative. In its company literature, Argent Energy estimates that the biodiesel market potential in 2005 is 414,000 tonnes and will increase to 1,478,000 tonnes by 2010(109) in order to meet UK targets for th ebiofuel directive. Argent make the salient point that mineral diesel cannot be produced without the production of petroleum and demand for petroleum has dropped from 5.4 MT in the second quarter of 2001 to 4.7 MT in Q2 of 2003. Diesel demand has increased 0.7 MT in the same period. Argent have invested in biodiesel production to help offset the difference in supply and demand.
Environmentally, Biodiesel is seen as preferable to mineral diesel. It produces less smoke and particulates, has higher cetane numbers, produces lower carbon monoxide and hydrocarbon emissions, is biodegradable and has the added benefit of being non-toxic. As mentioned previously, is also has low volatility, high pour, poor cloud and cold filter plugging points. However, it can also produce elevated nitrous oxide compounds (NOx.) and incomplete combustion is common. In order to maximise the positive and minimise the negative points of both fuels, a blending process is the preferred approach. The most commonly used blend is referred to as the B-20 blend. This enables the biodiesel element to have the desirable 2.2 weight percent of oxygenate in the B-20 fuel. Thus imparting the desired reduction in emissions, while minimising the power reduction due to the lower energy content of the bio fraction.
Unfortunately, the use of intact triglycerides creates serious issues with high viscosity and fuel injector fouling. Processing the raw oils using trans-esterification can quite easily overcome this. In the start of this document, I explained that fat is made up of one glycerol molecule, attached to 3 fatty acids by way of an ester bond. Using methanol, one can transfer these 3 fatty acids onto a methanol and simply recover and recycle of the old glycerol molecule. The end result is fatty acid methyl esters (FAME) and SCHEME (glycerol). Ethanol could also be used instead of methanol. Ethyl esters are less toxic and ethanol itself can be produced from grain, creating a totally bio based fuel source.
As one could expect, the cost of this production is prohibitive. To reduce the cost there has been research into using lower quality/ lower value lipids. Examples include waste greases from industry, of which grease trap waste is a fine example.
An example of localised Biodiesel schemes
Stoll et al (85) highlighted the need for frequent removal of fats from restaurants to protect the oil from impending rancidity. This rancidity liberated free fatty acids (FFA?s). The most commonly used catalysts for the trasnsesterification process are alkali hydroxides and alcoholates. When a restaurant wastewater has high FFA?s, some operators merely add excess alkali and subsequently remove the FFA portion as insoluble soap. (This soap stock is thought of as an underused by product with industrial potential). However, this reduces the final ester volumes and consumes alkali. An alternative is the acid-catalysed esterifacation, which simultaneously achieves transesterification of the glyceride and esterification of the FFA. It has the drawback of requiring higher temperatures and longer reaction times than the simper alkalicatalysed method.
Montgomery (63) shows how FFA of up to 40% can be used in biodiesel production. He must use a 2-step strategy. First, acid catalysed esterification converts FFA to esters. When FFA?s are below 0.5% a second base catalysed reaction is undertaken on the oil portion.
An alternative catalysation pathway is by using a specific enzyme known as ethyl greasate. This is an option for low-grade grease utilisation. The high FFA (>8%) and the glyceride-linked fatty acids are effectively converted into simple alkyl esters under enzyme action. Full conversion of FFA and glycerides is vital. Low residual amounts reduce the handling and performance characteristics of the fuel.
Zhang et al (99) propose a completely different use of biodiesel. In their document, they introduce the reader to the concept of co-metabolic biodegradation. The term is used to describe the process in which microorganisms use a second substrate (readily degradable) as the carbon (energy) source to degrade the primary substrate, which would not otherwise be attacked if it were the sole carbon source. This means that biodiesel would promote and accelerate the biodegradation of petroleum-based diesel in such as in industrial oil remediation and oil-tanker spillage incidents.
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