Biofuels come from the products of living organisms, such as methane biogas from decaying manure and sewage. Vegetable oils are also used as fuels for vehicles. Some of this biodiesel is made from waste cooking oil and rapeseed oil.
Ethanol is the type of alcohol found in alcoholic drinks such as wine and beer. It is also useful as a fuel. For use in cars and other vehicles it is usually mixed with petrol.
Ethanol can be made by a process called fermentation. This converts sugar from sugar cane or sugar beet into ethanol and carbon dioxide. Single-celled fungi, called yeast, contain enzymes that are natural catalysts for making this process happen:
C6H12O6 2C2H5OH + 2CO2
Advantages of using biofuels
Biofuels are carbon neutral, which means that they release only as much carbon dioxide when they burn as was used to make the original oil by photosynthesis.
You may wish to view this BBC News item (2005) about ethanol as an environmentally friendly fuel.
This helps to reduce global warming.
However, some people are concerned about whether it is ethical to use food crops in this way, instead of using them to feed hungry people.
Back to Fuels index
Advantages of biofuels
Biofuels have several advantages over fossil fuels [fossil fuel: Fuel, such as coal, oil and natural gas, made from the remains of ancient plants and animals.] . For example, biofuels:
produce less greenhouse gases [greenhouse gas: Carbon dioxide, methane and other gases that absorb infrared radiation in the atmosphere.] overall than fossil fuels when they are burned
are alternative sources to fossil fuels - allowing for greater fuel security for countries with little or no oil reserves of their own
may not produce any particulates, such as soot and other fine particles
Biofuels – Higher tier
The burning of biofuels does not cause an overall increase in greenhouse gases such as carbon dioxide if:
the biofuels are used at the same rate as the rate of production of biomass [biomass: The dry mass of an organism.]
land is not cleared of other plants just to make way for biofuel crops
Land being cleared so that new crops can be planted
However, in some countries large areas of land are being used for biofuel crops. This is causing loss of habitat [habitat: The physical space in which a given species lives.] and the extinction of some species of animals and plants.