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Clean Fuels: Biodiesel Frequently Asked Questions
The American Lung Association of the Upper Midwest provides this Lesson on Biodiesel as an educational reference.
Click here to download the print version of the Biodiesel FAQ
Lesson One: The Basics
What is biodiesel?
Biodiesel is an alternative fuel produced from vegetable oils, animal fats, or waste grease. Biodiesel itself contains no petroleum, but in most cases it is mixed with petroleum diesel to create a biodiesel blend. These blends are identified by the letter "B", followed by the corresponding level of biodiesel: B2 (two percent), B10 (10 percent), B20 (20 percent).
How is biodiesel produced?
Biodiesel is produced in a process called transesterification. This process is a reaction of the oil with an alcohol to remove the glycerin, which is a by-product of biodiesel production. This process separates fats from glycerin. The remaining products are biodiesel and a glycerin, commonly used in soaps. Fuel-grade biodiesel must be produced to strict industry specifications (ASTM D6751 for B100) in order to insure proper performance.
Is biodiesel the same as raw vegetable oil?
NO! Biodiesel is legally registered with the Environmental Protection Agency as a motor fuel for sale and distribution. Raw vegetable oil cannot meet biodiesel fuel specifications, and it is not a legal motor fuel in the United States. Research shows that vegetable oil or greases used in diesel engines at levels as low as 10%-20%, can cause long-term engine problems due to the greater viscosity of raw oils compared to that of diesel fuel.
Where can biodiesel be purchased?
Biodiesel is available nationwide. Drivers can purchase biodiesel blends from numerous fueling stations across the country. For an updated listing of stations, visit Biodiesel.org.
What are benefits of using biodiesel?
Biodiesel is clean. Using biodiesel instead of traditional petroleum diesel fuel can reduce emissions, including particulate pollution, air toxics and lifecycle carbon dioxide emissions associated with global climate change.
Biodiesel is renewable. Biodiesel can be produced from a variety of non-petroleum feedstocks—often locally available, renewable sources.
Biodiesel is made here. Whatever the source, the feedstocks can be produced locally. In 2007, ~ 450 million gallons of biodiesel were produced from locally grown materials - providing jobs and support to local economies and a shorter, more secure supply line to your community.
Biodiesel is high performance. Biodiesel adds lubricity and has a high cetane rating. Biodiesel has the highest energy balance of any alternative fuel.
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Lesson Two: Vehicle Technologies
What is a diesel engine?
Diesel vehicles operate by compression ignition. This means the diesel fuel is injected into the combustion chamber containing compressed air causing the fuel to self ignite. Diesel engines run solely on diesel fuels, including biodiesel, and ultra low sulfur diesel. With the major auto manufacturers producing more than 230 different diesel capable models in the last three decades, consumers have numerous options to choose from when interested in diesels.
The first diesel engine was patented by Rudolf Diesel in 1898. Oddly enough, the engine was powered by peanut oil, a very early form of biodiesel. Rudolf Diesel was eager to utilize vegetable oils as a form of fuel in the hopes of supporting agriculture in the countries that would rely heavily on the use of the diesel engine.
Is my diesel vehicle compatible with biodiesel?
Biodiesel can be used in any diesel engine with little to no modifications to the engine or the fuel system.
Is there a concern that biodiesel will gel in colder climates?
When properly blended for winter use, blends up to 20 percent (B20) can be used in cold climates. This has been proven in the region in municipal snowplows, heavy trucks, even fire engines using biodiesel all year.
Will using biodiesel void a vehicle warranty?
NO! Federal law prohibits the voiding of a warranty just because biodiesel was used. In fact, many major vehicle manufacturers have stated formally that the use of biodiesel blends up to B20 (20% percent) will not void their parts and workmanship warranties. The only instance in which a vehicle warranty would be voided would be if an engine experienced a failure caused by external conditions, such as bad diesel fuel.
How does biodiesel compare to petroleum diesel in terms of performance?
If B20 is used, there is no noticeable difference in power and torque, however fuel economy could decrease by 1%-2%, depending on the petroleum diesel blended with. Most users report little difference between B20 and the No. 2 diesel, and as biodiesel blend levels decrease, performance differences are nearly diminished between the two. Typically, biodiesel contains 8% less energy per gallon than No. 2 diesel in the United States. This difference is caused by an 11% increase in oxygen by weight in biodiesel.
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Lesson Three: How Much...?
How much energy does it take to produce biodiesel?
According to the latest U.S. Department of Energy facts, cleaner-burning biodiesel provides 3.5 units of energy for every one unit expended in production - the greatest energy return of any fuel approved for use as a legal motor fuel.
How much biodiesel can the U.S. produce?
According to the National Biodiesel Board, 171 biodiesel plants across the United States have the capacity to produce 2.24 billion gallons of biodiesel per year. With the current companies and 60 additional plants reported to be under construction the combined capacity could reach 1.23 billion gallons per year of biodiesel production nationwide.
How many soybeans does it take?
One bushel of soybeans (60 pounds) yields about 1.44 gallons of B100 biodiesel and 44 pounds of animal feed.
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Lesson Four: The Environment
What effect does biodiesel have on global warming?
Using biodiesel instead of petroleum-based fuels can reduce lifecycle emissions of carbon dioxide. In a 1998 biodiesel lifecycle study conducted by the US Departments of Energy and Agriculture, biodiesel was found to reduce net carbon dioxide (CO2 )emissions by 78 percent compared to petroleum diesel. With biodiesel there exists a "carbon cycle" in which the carbon released into the atmosphere by burning biodiesel is reabsorbed by the next generation of energy crops grown to produce biodiesel. Use of fossil fuels, like petroleum diesel, unlocks carbon that has been stored in the earth for millions of years.
Is the speculation true that biofuels cause global warming?
NO! While some well-publicized studies have suggested this, they are based on computer models and speculation on global land use to grow biofuels crops. The newly passed Energy Act expressly prevents uncultivated land to be used for biofuel crops. Because the United States imports very little of its biofuel, there is little incentive for foreign farmers to convert forests and prairies into fields to meet our biofuel needs. While not all nations protect their natural resources equally, responsibility for global deforestation and poor land management decisions made overseas can not be reasonably be attributed to biofuel use in the United States.
How do biodiesel emissions compare to that of petroleum diesel?
The use of biodiesel in a conventional diesel engine results in substantial reduction of unburned hydrocarbons, carbon monoxide, and particulate matter compared to emissions from diesel fuel. In addition, the exhaust emissions of sulfur oxides and sulfates (major components of acid rain) from biodiesel are essentially eliminated compared to diesel. Of the major exhaust pollutants, both unburned hydrocarbons and nitrogen oxides are ozone or smog forming precursors. The use of biodiesel results in a substantial reduction of unburned hydrocarbons. Emissions of nitrogen oxides are either slightly reduced or slightly increased depending on the duty cycle of the engine and testing methods used. Based on engine testing, using the most stringent emissions testing protocols required by the Environmental Protection Agency (EPA) for certification of fuels additives, the overall ozone forming potential of the speciated hydrocarbon emissions from biodiesel was nearly 50 percent less than that measured for diesel fuel.
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