Biodiesel Benefits and Considerations

Biodiesel is a domestically produced, renewable substitute for petroleum diesel. Using biodiesel as a vehicle fuel improves public health and the environment, provides safety benefits, and contributes to a resilient transportation system.

Engine Operation

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 improve the lubricity of diesel fuel, even at very low levels. The amount of biodiesel required depends on the specific properties of the diesel fuel, but 2% biodiesel is almost always sufficient for adequate lubricity.

Before using biodiesel, check your engine original equipment manufacturer (OEM) recommendations to determine the allowable blend for your vehicle (see the Engine Technology Forum’s list of diesel vehicles available in the United States for light-duty vehicles and a fact sheet from Clean Fuels Alliance America for heavy-duty vehicles that are compatible with biodiesel.)

Safety

Biodiesel in its pure, unblended form 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. For additional guidance on handling, storing, and transporting biodiesel, reference the Biodiesel Handling and Use Guide (Sixth Edition).

Energy Security

The transportation sector accounts for approximately 30% of total U.S. energy needs and 70% of U.S. petroleum consumption. Using biodiesel and other alternative fuels and advanced technologies to provide energy-efficient transportation options strengthens national energy security by increasing flexibility during natural disasters and fuel supply disruptions.

Biodiesel is produced in the United States and used in conventional diesel engines, directly substituting for or extending supplies of traditional petroleum diesel. Soybean biodiesel has a positive energy balance, meaning that soybean biodiesel yields 4.56 units of energy for every unit of fossil energy consumed over its life cycle.