Biofuels are derived from biological sources such as plants and algae.
With dwindling fossil fuel supplies, many types of biofuels such as ethanol and vegetable oils are now being used for transport, industrial and domestic purposes.
“Good biofuels” are produced from waste organic matter that is not produced from environmentally destructive activities.
For example, using crop waste that would otherwise be burnt (such as residual waste after sugar can harvesting) can produce useful quantities of fuel such as ethanol.
“Bad biofuels” are:
- Those produced using fossil fuel inputs (e.g. for fertiliser, harvesting, manufacturing and distribution) that exceeds the energy value of the fuel, as is the case for ethanol produced from corn crops in the United States
- Palm oil – where large tracts of rainforest are cleared to create new plantations
- Woodchips from native forest logging – huge carbon emissions result from the clearing of the native forests, and the burning of woodchips
Scientific study concludes that biofuels increase carbon emissions
Growing crops to make biofuels results in vast amounts of carbon dioxide being released into the atmosphere and does nothing to stop climate change or global warming, according to the first thorough scientific audit of a biofuel’s carbon budget.
Scientists have produced damning evidence to suggest that biofuels could be one of the biggest environmental con-tricks because they actually make global warming worse by adding to the man-made emissions of carbon dioxide that they are supposed to curb. Two separate studies published in the journal Science show that a range of biofuel crops now being grown to produce “green” alternatives to oil-based fossil fuels release far more carbon dioxide into the air than can be absorbed by the growing plants. 
- Britain to put brakes on biofuels, Australian Broadcasting Corporation, July 8, 2008
- The great biofuels con, The Age
- Biofuels make climate change worse, scientific study concludes, The Independent