Is global warming natural as well as man-made? What effect will arctic melting have on our sea levels? Why have cars not evolved past piston engines and fossil fuels? Can sugars be used to fuel cars? We tackle these energy-related questions on this week's show as well as reveal how iron ships are kept buoyant, how inkjet printers work and how many wind turbines are needed to power the UK. Plus we investigate how much of our coastline is eroding each year and how old the water is that comes out of our taps!