Biodiesel is a liquid fuel made up of fatty acid alkyl esters, fatty acid methyl esters (FAME), or long-chain mono alkyl esters. It is produced from renewable sources such as new and used vegetable oils and animal fats and is a cleaner-burning replacement for petroleum-based diesel fuel. It is nontoxic and biodegradable. Biodiesel has physical properties similar to those of petroleum diesel:
| Biodiesel's Physical Characteristics | |
|---|---|
| Specific gravity | 0.87 to 0.89 |
| Kinematic viscosity @ 40°C | 3.7 to 5.8 |
| Cetane number | 46 to 70 |
| Higher heating value (btu/lb) | 16,928 to 17,996 |
| Sulfur, wt% | 0.0 to 0.0024 |
| Cloud point °C | -11 to 16 |
| Pour point °C | -15 to 13 |
| Iodine number | 60 to 135 |
| Lower heating value (btu/lb) | 15,700 to 16,735 |
Like petroleum diesel, biodiesel is used to fuel compression-ignition (diesel) engines. Low-level blends of biodiesel with petroleum diesel also provide benefits.