Even the electricity that the bioethanol factories use comes from burning sugar cane. Burning biofuels produces gases like co but when we grow them, the plants take Co, out of the air. Because of this, sugar cane bioethanol produces 78 per cent less Co, than petrol. The newest biofuels are made from very small living things called algae. Algae produce more energy than other biofuels, and they can grow in places where we do not grow food, like seas and waste land. In the future, people want to change the way that some bacteria and plants grow. In this way they hope to get biofuels that work better or grow in different places. One day there may be huge algae farms in the sea, and many buildings may grow biofuel plants on their roofs Driving on air! Electric cars do not burn fuel: devices called batteries keep electricity and use it to power the engine. People have driven them for years, and they are a great way to have less pollution in city centres, but where does the electricity come from? It may come from burning coal, for example.