Biofuels
Installations to produce biofuels from wood are different to plants producing other biofuels such as biodiesel for example. The feedstock for biodiesel production is usually an oil crop such as oilseed rape: this needs to be pressed to extract the oil which is then chemically altered and refined to make the biodiesel.
Bioethanol can be produced from forest residues or short rotation coppice by breaking down the lignin and cellulose in woody material. The cellulose is hydrolysed and the resulting sugars can then be fermented to produce bioethanol. The potential yield of ethanol is from 170 to 280 litres per tonne input.
Pyrolysis of wood produces gases, liquids and charcoals. To produce liquid fuels, logs or chips are loaded into a retort which is heated from outside with air excluded. For gasificiation, the wood is fired with a carefully controlled air supply. In both cases the resulting fuels will need further refining. The liquid fuels can be processed, transported and used in the same way as existing petroleum products. The gas products are best used on site to reduce the need for bulk storage and compression. Wood gas is a mixture of hydrogen and carbon monoxide which is potentially explosive and poisonous, therefore it is not best suited for bottled distribution.