Bio-diesel is produced through a process known as transesterification, which separates glycerine from vegetable oil, leaving biodiesel as a product. The glycerine can then be used in the making of other products, such as soap. Bio-diesel can be used as a straight fuel, or blended with mineral diesel to create a diesel blend, both types can be used without any engine modification.

Dr Rudolf Diesel actually invented the diesel engine to run on vegetable oil, stating in 1913 that “The use of vegetable oils for engine fuels may seem insignificant today but such oils may become in course of time as important as petroleum.”

More than 700,000 litres of bio-diesel are sold every month in the UK, from around 100 filling stations.

A particular advantage of bio-diesel is that being highly biodegradable it does not pollute soil and waterways if spilt, posing less of an environmental risk than fossil fuels.