Biodiesel Fuel Basics

Related Information

Biodiesel is a domestically produced, renewable fuel that can be manufactured from vegetable oils, animal fats, or recycled restaurant grease. It is a cleaner-burning replacement for petroleum diesel fuel. It is nontoxic and biodegradable.

Biodiesel is a liquid fuel often referred to as B100 or neat biodiesel in its pure, unblended form. Like petroleum diesel, biodiesel is used to fuel compression-ignition engines, which run on petroleum diesel. See the table for biodiesel's physical characteristics.

How well biodiesel performs in cold weather depends on the blend of biodiesel. The smaller the percentage of biodiesel in the blend, the better it performs in cold temperatures. Regular No. 2 diesel and B5 perform about the same in cold weather. Both biodiesel and No. 2 diesel have some compounds that crystallize in very cold temperatures. In winter weather, manufacturers combat crystallization in No. 2 diesel by adding a cold flow improver. For the best cold weather performance, drivers should use B20 made with No. 2 diesel manufactured for cold weather.

Biodiesel's Physical Characteristics
Specific gravity0.88
Kinematic viscosity at 40°C4.0 to 6.0
Cetane number48 to 65
Higher heating value, Btu/gal127,042
Lower heating value, Btu/gal118,170
Density, lb/gal at 15.5°C7.3
Carbon, wt%77
Hydrogen, wt%12
Oxygen, by dif. wt%11
Boiling point, °C315-350
Flash point, °C100-170
Sulfur, wt%0.0 to 0.0024
Cloud point, °C-3 to 15
Pour point, °C-5 to 10