ABSTRACT
Today there is a limited return to the use of oils and fats for some of these purposes, mainly on environmental grounds. Oil and gas supplies are not known with certainty, but they are finite and will not last indefinitely. Oils and fats can sometimes be used in place of fossil fuels and are even being burnt in electrical power stations to reduce the
levels of burdensome stocks, to raise prices by removal of excess oil, or to meet targets for the reduction of carbon dioxide production. In contrast to fossil fuels, oils and fats represent a renewable resource produced by agricultural systems from carbon dioxide and water with sunlight providing the necessary energy. But some numbers should be applied to this issue to maintain a sense of perspective. Annual production of mineral oil, at 3.5 billion tonnes, is almost 30 times that of oils and fats, and the greater part of these latter are essential for food purposes. For example, biodiesel can never replace the demand for conventional fossil fuel — it can only diminish it marginally (Dumelin, 2005). Other environmental reasons are based on the fact that oils and fats are biodegraded more quickly than petrochemical products and, therefore, disappear more easily from the environment when used or spilled. Finally, when fully degraded, these materials liberate carbon dioxide trapped only months earlier and, therefore, do not add to total carbon dioxide, one of the greenhouse gases responsible for global warming. This contrasts with petrochemical products, which are oxidised to carbon dioxide trapped millennia earlier.
