Nokia has its bicycle-powered mobile phone charger. And now Orange has its 'Power Wellies'; thermoelectric wellington boots that are perfect for summer festivals because they can charge a mobile phone by using heat from your feet.
The prototype footwear, created in collaboration with renewable energy organisation GotWind, uses a sole that converts heat from your feet into an electrical current. It's a phenomenon known as the Seebeck effect. Apparently 12 hours of walking generates an hour of talk time, with hotter feet generating energy more quickly.
This is the fourth year that GotWind has worked with Orange to create a charging prototype for festival-goers. Orange is Official Communications Partner for the Glastonbury Festival.
