Biomass is pre-treated and then transformed to synthesis gas via gasification. The resulting syngas is then cleaned preliminary to conversion to liquid biofuels, typically via Fischer Tropsch or the Mobil process. There are two main biomass-based liquid propellant in the market place today, ethanol and biodiesel. Some 20 Mm 3 y -1 of ethanol is produced with an energy content of 425 PJ, manufacturing this the second most important biofuel. A much smaller amount of biodiesel is used in the USA and Europe. Generally a tonne of cane produces between 125 and 140 kg of raw sugar, or between 70 and 80 litres of ethanol, although a tonne of maize, with about 70% to 75% starch content, will produce between 440 and 460 L t -1 with wet and dry corn crushing, respectively.