BBC: Royal Dutch Shell is selling a biofuel made from straw at one of their service stations in Canada. The station in Ottawa will sell a blend of cellulosic ethanol and petrol. Biofuels have been hailed as a way to fight climate change, but have also been criticised for their potential impact on food stocks and prices. This biofuel, however, is made from a non-food portions of crops, such as corn stalks and corn cobs, which are renewable, according to Shell. Such …