Electric cars are being used to help power a small Portuguese island in the Atlantic. Click here to watch the BBC video.

Porto Santo Island has begun testing a scheme in which the batteries in electric vehicles are charged by solar power during the day but at night return spare energy to the grid to power people's homes.

Some experts say this form of energy storage could become a global trend.

For more information on how you can rent an electric, hybrid or low emission car from Green Motion in Portugal and around the world visit www.greenmotion.com