Frequently Asked Questions From Biodiesel.Org

What is biodiesel?
Biodiesel is the name of a clean burning alternative fuel produced from domestic,
renewable resources. Biodiesel contains no petroleum, but it can be blended at any
level with petroleum diesel to create a biodiesel blend. It can be used in compression ignition (diesel) engines with no major modifications. Biodiesel is simple to use,
biodegradable, nontoxic, and essentially free of sulfur and aromatics.

Technical Definition: Biodiesel, n—a fuel composed of mono-alkyl esters of long chain fatty acids derived from vegetable oils or animal fats, designated B100, and meeting the requirements of ASTM (American Society for Testing & Materials) D 6751.

Is biodiesel used as a pure fuel or is it blended with petroleum diesel?
Biodiesel can be used as a pure fuel or blended with petroleum in any percentage.
B20 (a blend of 20 percent biodiesel with 80 percent petroleum diesel) has
demonstrated significant environmental benefits with a minimum increase in cost for
fleet operations and other consumers.

Is it approved for use in the U.S.?
Biodiesel is registered as a fuel and fuel additive with the Environmental Protection
Agency (EPA) and meets clean diesel standards established by the California Air
Resources Board (CARB). Neat (100 percent) biodiesel has been designated as an
alternative fuel by the Department of Energy (DOE) and the U.S. Department of
Transportation (DOT).

How do biodiesel emissions compare to petroleum diesel?
Biodiesel is the only alternative fuel to have fully completed the health effects testing
requirements of the Clean Air Act. The use of biodiesel in a conventional diesel engine results in a 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 protocol required by EPA for certification of fuels or fuel additives in the U.S., the overall ozone (smog) forming potential of the hydrocarbon exhaust emissions from biodiesel is nearly 50 percent less than that measured for diesel fuel.

Can I use biodiesel in my existing diesel engine?
Biodiesel works in any diesel engine with few or no modifications to the engine or the
fuel system. Biodiesel has a solvent effect that may release deposits accumulated on
tank walls and pipes from previous diesel fuel usage. The release of deposits may end up in fuel filters initially, so fuel filters should be checked more frequently at first. Ensure that only fuel meeting the biodiesel specification (D 6751) is used.