Biodiesel is non-petroleum diesel fuel consisting of monoalkyl (methyl, ethyl or propels) esters of long-chain alkyl esters, made by trans – etherification of vegetable oil or animal fat (tallow), which can be used (alone or blended with conventional petroleum diesel) in unmodified diesel-engine vehicles.
Biodiesel is distinguished from the straight vegetable oil ( waste vegetable oil, used directly as diesel) fuels in some converted diesel vehicles.
The use of vegetable oil as a fuel source in diesel engines is as old as the diesel engine itself. However, the demand to develop and utilize plant oils and animal fats as biodiesel fuels have been limited until recently.
The main benefit of biodiesel is that it can be described as ‘carbon neutral’. This means that the fuel produces no net output of carbon in the form of carbon dioxide (CO2). This effect occurs because when the oil crop grows it absorbs the same amount of CO2 as is released when the fuel is combusted.