Biodiesel filling station. A man fills his car with biodiesel, a fuel derived from rapeseed oil. Biodiesel, or rapeseed methyl ester, is made by transesterification of rapeseed oil. The fuel can be used in conventional diesel engines without modification and produces no sulphur-containing emissions - the main cause of acid rain. Because the continual growth of new rape absorbs carbon dioxide from the air, use of biodiesel contributes less to the greenhouse effect than fossil fuels. Its main drawbacks are expense of production and engine damage by deposition of charred carbon on fuel injection nozzles. Photographed in Germany.