Biodiesel

Biodiesel refers to a diesel-equivalent processed fuel derived from biological sources (such as vegetable oils) which can be used in unmodified diesel-engine vehicles. It is thus distinguished from the straight vegetable oils (SVO) or waste vegetable oils (WVO) used as fuels in some diesel vehicles.

In this article's context, biodiesel refers to alkyl esters made from the transesterification of vegetable oils or animal fats.

On August 31, 1937, G. Chavanne of the University of Brussels (Belgium) was granted a patent for a 'Procedure for the transformation of vegetable oils for their uses as fuels' (fr. 'Procédé de Transformation d’Huiles Végétales en Vue de Leur Utilisation comme Carburants') Belgian Patent 422,877. This patent described the alcoholysis (often referred to as transesterification) of vegetable oils using ethanol (and mentions methanol) in order to separate the fatty acids from the glycerol by replacing the glycerol with short linear alcohols. This appears to be the first account of the production of what is known as 'biodiesel' today.

Biodiesel is biodegradable and non-toxic, and typically produces about 60% less net carbon dioxide emissions than petroleum-based diesel, as it is itself produced from atmospheric carbon dioxide via photosynthesis in plants. Pure biodiesel is available at many gas stations in Germany.

Some vehicle manufacturers are positive about the use of biodiesel, citing lower engine wear as one of the benefits of this fuel. However, as biodiesel is a better solvent than standard diesel, it 'cleans' the engine, removing deposits in the fuel lines, and this may cause blockages in the fuel injectors. For this reason, car manufacturers recommend that the fuel filter be changed a few months after switching to biodiesel (this part is often replaced anyway in regular servicing). Most manufacturers release lists of the cars that will run on 100% biodiesel.

Other vehicle manufacturers remain cautious over use of biodiesel. In the UK many only maintain their engine warranties for use with maximum 5% biodiesel — blended in with 95% conventional diesel — although this position is generally considered to be overly cautious.citation needed] Scaniacitation needed] and Volkswagen are exceptions, allowing most of their engines to operate on 100% biodiesel. Peugeot and Citroën are also exceptions in that they have both recently announced that their PSA HDi engine can run on 30% biodiesel. The Ford Focus has recently been converted to run on Biodiesel.

Branson's Virgin Voyager, number 220007 Thames Voyagercitation needed] was converted to run on Biodiesel, although an adverse effect occurred when it was proven to reduce reliability significantly, and to raise costs of maintenance also, significantly.

Biodiesel can also be used as a heating fuel in domestic and commercial boilers. Existing oil boilers may require conversion to run on biodiesel, but the conversion process is believed to be relatively simple.

Biodiesel can be distributed using today's infrastructure, and its use and production are increasing rapidly. Fuel stations are beginning to make biodiesel available to consumers, and a growing number of transport fleets use it as an additive in their fuel. Biodiesel is generally more expensive to purchase than petroleum diesel but this differential may diminish due to economies of scale, the rising cost of petroleum and government tax subsidies. In Germany, biodiesel is generally cheaper than normal diesel at gas stations that sell both products.