The biomass: biogas
The biomass encompasses all living matter (plant life and animals). The three main sources of energy produced by the biomass are wood, biogas and bio-fuels: Wood is the oldest source of energy used by humans. Whilst it is little used in Europe these days, it remains the number one source of energy for several billion people around the world, who use it for cooking and heating. Biogas is produced from biodegradable waste matter. Biogas is like natural gas, but is not a form of fossil energy. Bio-fuels are made from farming products (wheat, rape, corn, etc.). They can be used as a substitute for petrol, heating oil or diesel fuel, or can be blended in small quantities with these forms of fuel.
These sources of energy are renewable as long as the crops are re-sown after they are harvested. The way in which these crops are grown is also important: the use of fertilisers and chemical pesticides, which themselves are produced using crude oil, can dilute their genuine renewable nature.
