Some people say that buying an electric car is a great way to fight climate change - but if they use electricity that is made by burning fossil fuels, are they really more environmentally friendly than gas powered cars?
Biofuels can provide energy without the reliance on environmentally harmful fossils fuels -- but scientists are still searching for a plentiful source. Craig A. Kohn demonstrates how cellulose, the naturally abundant tough walls of plant cells, might be the solution.