Biodiesel Fuel

Biodiesel is a light-yellow to dark-yellow liquid, with a viscosity similar to standard diesel fuel. It is a non-petroleum-based processed fuel derived from vegetable oils, principally soybeans but also rapeseed (canola), which can be used in diesel vehicles. Yellow grease, which is primarily recycled cooking oil from restaurants, can also be used as a diesel fuel. Vegetable oil as a base for fuel oil in diesel engines has been around for many years; however, commercial production of biodiesel did not begin until the 1990s. Some modified diesel engines can run on straight vegetable oil (SVO) or on waste vegetable oil (WVO).

Commercial blends of biodiesel and petroleum diesel are designated with the letter “B” followed by the volumetric percentage of biodiesel in the blend. The blend most commonly available is B20; it contains 20% biodiesel and 80% petroleum diesel. B100 is pure biodiesel. Commercially processed biodiesel blended fuels can run in any diesel engine designed for petroleum-based diesel fuels.

Biodiesel is generally more expensive to produce than petroleum diesel. However, in some countries, such as Germany, biodiesel can be cheaper to buy than regular diesel fuel because of taxes and subsidies. Biodiesel blends actually tend to perform better than petroleum diesel. Unfortunately, high production costs and limited availability of raw materials continue to limit wholesale commercial implementation.

Biodiesel fuel has some drawbacks. It can make the engine harder to start and produce less power and more smoke than standard diesel fuel. It is hygroscopic, meaning that although it is oil-based and does not readily mix with water, it attracts water from the atmosphere. Contamination with moisture can corrode components such as pumps and injectors, as well as encourage the growth of microbes in the vegetable fuel. Biodiesel fuel can also degrade natural rubber gaskets and hoses. This is not a major problem as most components are now made of synthetic rubber, which is not affected.