Biodiesel Benefits and Considerations
Biodiesel is a domestically produced, clean-burning, renewable substitute for petroleum diesel. Using biodiesel as a vehicle fuel increases energy security, improves air quality and the environment, and provides safety benefits.
Energy Security and Balance
The United States imported 27% of its petroleum in 2014, two-thirds of which is used to fuel vehicles in the form of gasoline and diesel. Depending heavily on foreign petroleum supplies puts the United States at risk for trade deficits, supply disruption, and price changes. Biodiesel is produced in the U.S. and used in conventional diesel engines, directly substituting for or extending supplies of traditional petroleum diesel. Biodiesel has a positive energy balance meaning that biodiesel yields 4.56 units of energy for every unit of fossil energy consumed over its lifecycle. (See USDA study for more details)
Engines manufactured in 2010 and later have to meet the same emissions standards, whether running on biodiesel, diesel, or any alternative fuel. Selective catalytic reduction (SCR) technology in diesel vehicles, which reduces nitrogen oxide (NOx) emissions to near zero levels, makes this possible. These engines are some of the cleanest engines on the road, and the emissions from diesel fuel are comparable to those from biodiesel blended fuel.
Using biodiesel reduces greenhouse gas emissions because carbon dioxide released from biodiesel combustion is offset by the carbon dioxide absorbed while growing the soybeans or other feedstock. B100 use reduces carbon dioxide emissions by more than 75% compared with petroleum diesel. Using B20 reduces carbon dioxide emissions by 15%.
Greenhouse gas and air-quality benefits of biodiesel are roughly commensurate with the amount of biodiesel in the blend. B100 use could increase nitrogen oxides emissions, although it greatly reduces other emissions. Learn more about Biodiesel Emissions.
Biodiesel improves fuel lubricity and raises the cetane number of the fuel. Diesel engines depend on the lubricity of the fuel to keep moving parts from wearing prematurely. One unintended side effect of the federal regulations, which have gradually reduced allowable fuel sulfur to only 15 ppm and lowered aromatics content, has been to reduce the lubricity of petroleum diesel. To address this, the ASTM D975 diesel fuel specification was modified to add a lubricity requirement (a maximum wear scar diameter on the high-frequency reciprocating rig [HFRR] test of 520 microns). Biodiesel can increase fuel lubricity to diesel fuels at blend levels as low as 1%.
Before using biodiesel, check your engine manufacturer recommendations to determine what blend is optimal for your vehicle (see the National Biodiesel Board's OEM Information for those that support the use of biodiesel blends).
Biodiesel causes far less damage than petroleum diesel if spilled or released to the environment. It is safer than petroleum diesel because it is less combustible. The flashpoint for biodiesel is higher than 130°C, compared with about 52°C for petroleum diesel. Biodiesel is safe to handle, store, and transport.