Alternative Energies Update

Carbon nanotubes are used to create direct and efficient solar propulsion for water vehicles:

http://www.technologyreview.com/energy/22423/

"When light is focused onto it, a boat about a centimeter long can travel as fast as eight centimeters per second. The second machine is a simple rotor with one nanotube strip on one side of each of its four fins. When exposed to direct sunlight, it spins at about 70 rotations per minute."