What is Biodiesel?


                               What is biodiesel in simple terms?            Download PDF

Biodiesel PumpYou may have wondered “What is biodiesel?” Biodiesel is an alternative clean burning fuel produced from renewable domestic resources. Although biodiesel contains no petroleum it can be blended at any level with petroleum diesel to create a biodiesel blend. Biodiesel is used in diesel (compression ignition) engines with no major modifications. In addition, biodiesel can be used as a fuel in fuel oil furnaces with little or no modifications. Biodiesel is nontoxic, biodegradable, simple to use, and basically free of sulfur and aromatics.

Biodiesel’s Chemical Definition

Biodiesel is a fuel composed of mono-alkyl esters of long chain fatty acids derived from vegetable oils or animal fats. At 100% pure, biodiesel is called B100 or neat. B100 fulfills the requirements of ASTM (American Society for Testing & Materials) D 6751. Biodiesel exists in 2 common forms, either as methyl-ester or ethyl ester. Methyl-ester biodiesel is derived from the chemical reaction between vegetable oils (triglycerides), methanol, & sodium hydroxide (lye). Ethyl-ester is obtained from the chemical reaction between vegetable oils (triglycerides), ethanol, & potassium hydroxide.

Is biodiesel used as a pure fuel?

Biodiesel can be used as a pure fuel or blended with petroleum in any percentage. Even in its diluted form, B20 (a blend of 80% by volume petroleum diesel with 20% by volume biodiesel) has demonstrated significant environmental benefits with a minimum increase in cost for fleet operations and other consumers.

Is biodiesel approved for use in the United States?

Biodiesel is registered as a fuel and fuel additive with the Environmental Protection Agency. As such, biodiesel fulfills the clean diesel standards established by the California Air Resources Board (CARB). Neat (B100) biodiesel has been designated as an alternative fuel by the the US Department of Transportation and the Department of Energy.

Regarding emissions, how does biodiesel compare to petroleum diesel?

Biodiesel is the only alternative fuel that successfully meets the health effects testing requirements of the Clean Air Act. Regarding diesel engine emissions, biodiesel consumption significantly reduces the emissions of carbon monoxide, unburned hydrocarbons, & particulate matter in comparison to petroleum diesel consumption. Also, biodiesel essentially eliminates the exhaust emissions of sulfates & sulfur oxides (major components of acid rain) when compared to petroleum diesel. Engine tests conducted with the strictest EPA emissions test protocols have shown that the total ozone forming potential from biodiesel emissions is approximately 50% less than that from petroleum diesel emissions.

Can biodiesel help alleviate “global warming”?

In 1998 an in-depth biodiesel life-cycle study was conducted under joint sponsorship by the U.S. Department of Agriculture and the U.S. Department of Energy. The study found that biodiesel consumption reduces net carbon dioxide emissions by 78% in comparison to petroleum diesel. This phenomenon is a result of biodiesel’s closed carbon cycle. The CO² released into the atmosphere when biodiesel is burned is recycled by growing plants, which are later processed into fuel.

Regarding human health, is biodiesel better than petroleum diesel?

Scientific investigations have confirmed that biodiesel emissions are less harmful to human health than petroleum diesel emissions. Biodiesel exhaust contains lower levels of polycyclic aromatic hydrocarbons (PAH) and nitrited PAH compounds (known potential carcinogens). PAH compounds are reduced by 75-85%. Tetraphene (also known as benzo(a)anthracene) emissions are reduced by 50%. Biodiesel use significantly reduces nitrated PAH emissions. 1-nitropyrene & 2-nitrofluorene emissions are 90% lower with biodiesel fuel in comparison to petroleum diesel.

Can I fuel my existing diesel engine with biodiesel?

Biodiesel runs in any diesel engine with little or no modifications to the fuel system or the engine. Biodiesel has a solvent effect which may release deposits accumulated on tank walls and pipes from previous petroleum diesel fuel storage. Said deposits can initially clog fuel filters and precautions should be taken. Only employ biodiesel fuel that meets the D 6751 specification.

Does biodiesel require special storage facilities?

The standard handling & storage procedures used for petroleum diesel can be used for biodiesel. Biodiesel should be stored in a dry, dark, clean environment. Steel, aluminum, fluorinated polypropylene, fluorinated polyethylene, and teflon are acceptable storage tank materials. Do not use lead, tin, zinc, copper, or brass materials for biodiesel storage or fluid transfer.

Regarding alternative fuels, is biodiesel more expensive to use?

Other alternative fuel systems encumber high operating costs. Over the years many fleet managers have concluded that biodiesel is their minimum-cost-solution for compliance with federal & state regulations. Simply put, biodiesel use requires no major engine modifications. In other words, operators keep their spare parts inventories, their refueling stations, their skilled mechanics, & their fleets. The only change? Biodiesel changes air quality for the better.

For Further Reading & Reference

  1. Greg Pahl, Biodiesel, Growing a New Energy Economy (White River Junction, VT: Chelsea Green Publishing Company, 2005), pp. 56-60.
  2. Joshua Tickell, From the Fryer to the Fuel Tank: The Complete Guide to Using Vegetable Oil as an Alternative Fuel (New Orleans, LA: Josh Tickell Media Productions, 2003), pp. 35-46.
  3. National Biodiesel Board, www.nbb.org

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Kevin is an engineer, physicist, and author. As a result, his creations span the globe. He has a knack for developing simple smart solutions to difficult problems. He is the creator of the MakeTrix. The MakeTrix fulfills Kevin’s lifelong dream. His dream is to provide free technical solutions to the world.