Biodiesel Fuel Basics
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 made up of fatty acid alkyl esters, fatty acid methyl esters, or long-chain mono alkyl esters. Like petroleum diesel, biodiesel is used to fuel compression-ignition engines, which run on petroleum diesel. See the chart for biodiesel's physical characteristics.
The cold-flow properties of biodiesel blends vary depending on the amount of biodiesel in the blend. 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 flow improvers. For the best cold weather performance, drivers should use B20 made with No. 2 diesel manufactured for cold weather.
| Specific gravity | 0.88 |
|---|---|
| Kinematic viscosity at 40°C | 4.0 to 6.0 |
| Cetane number | 48 to 65 |
| Higher heating value, Btu/gal | 127,042 |
| Lower heating value, Btu/gal | 118,170 |
| Density, lb/gal at 15.5°C | 7.3 |
| Carbon, wt% | 77 |
| Hydrogen, wt% | 12 |
| Oxygen, by dif. wt% | 11 |
| Boiling point, °C | 315-350 |
| Flash point, °C | 100-170 |
| Sulfur, wt% | 0.0 to 0.0024 |
| Cloud point, °C | -3 to 15 |
| Pour point, °C | -5 to 10 |
