Maybe it's fine to play football in the house...?

How playing football indoors could light your home: Scientists create ball that harnesses kinetic energy to power LED lamp for up to THREE HOURS

A team of Harvard alumni at non-for-profit organisation, Uncharted Play have created a football that can power an LED lamp for three hours after just 30 minutes play.

Full Story:
http://www.dailymail.co.uk/sciencetech/article-2288000/How-kicking-football-light-home-Scientists-create-ball-harnesses-kinetic-energy-power-LED-lamp-THREE-HOURS.html