General Motors is developing a new method of making ethanol that addresses some of the environmental concerns usually associated with producing biofuels. The process is claimed to use significantly less water and energy than making ethanol from grain. Instead, the fuel is made from a wide variety of waste materials, such as wood chippings, food waste and even used tyres and plastics. Ethanol production using grain is often criticised for taking away land needed to grow food, while planting palm oil for ethanol is often at the expense of virgin rainforest, which helps to reduce CO2. Pioneered by US company Coskata, the new process also uses significantly less energy than standard ethanol production – one unit of energy used in production produces 7.7 units in ethanol form. Ethanol from grain uses one unit to create 1.6 units of energy. Water use is also cut; a gallon of water is required for a gallon of ethanol, compared to the three to four gallons needed in conventional production.At the project's announcement at Detroit yesterday, General Motors’ president Rick Wagoner said there were currently six million vehicles in the US capable of running on ethanol, and if all of these cars, plus the ones that will be made in the next four years, used the fuel the US could save 29 billion gallons of petrol.