All fossil fuels are derived from organic material and their use involves the conversion of the chemical energy that has been locked away by plants and animals into energy for heat, transport or electricity generation. Diesel and petrol are the result of organic material that existed millions of years ago, which has died, decomposed and formed oil deposits over a long time period. The use of such reserves through the extraction and refinement of oil (to produce, amongst others, petrol and diesel) is occurring significantly faster than the time required for the natural production of such reserves, meaning the resource will eventually run out. Further (and critically to climate change), carbon is not being absorbed from the atmosphere to produce these reserves at the same rate as the carbon is being released through their extraction and use to produce energy.
Biofuels are also derived from organic plant matter, however the production of the fuel must occur at least at the same rate as the use of the fuel, and is therefore sustainable. This means that any carbon dioxide (and other greenhouse gases) released through the use of biofuels is being absorbed from the atmosphere (through photosynthesis) at a similar rate. There should not therefore be a net release of greenhouse gas emissions as a result of the use of biofuels. The production of biofuels involves the processing of organic material (typically through the application of heat, fermentation and the application of chemicals) to refine a fast growing plant species, such as sugercane, into a fuel such as ethanol.
In reality, the production of biofuels using current technology is a highly energy intensive process, requiring pesticides (which require energy to produce), the energy to process and refine organic matter and energy associated with planting and harvesting crops. If this energy is not sourced from low carbon sources, the climate benefits of biofuels are eroded by increasing emissions through the ancillary activities. Further, the land required to grow biofuels may compete with land for growing food crops, with the potential to impact the availability and/or price of food.
