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 11% of its petroleum in 2018, and transportation was responsible for nearly three-quarters of total U.S. petroleum consumption. 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 United States 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 life cycle. (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. The emissions from diesel fuel are comparable to those from biodiesel blends.
Using biodiesel reduces emissions because carbon dioxide released from biodiesel combustion is offset by the carbon dioxide absorbed from growing soybeans or other feedstocks used to produce the fuel. Life cycle analysis completed by Argonne National Laboratory found that B100 use reduces carbon dioxide emissions by 74% compared with petroleum diesel. The California Air Resources Board (CARB) reported similar values from various sources for its life cycle analysis of biodiesel.
Air-quality benefits of biodiesel are roughly commensurate with the amount of biodiesel in the blend. 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 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 original equipment manufacturer (OEM) 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.