A group of students from MIT have won the MIT and Dow Materials Engineering contest with their electrical charging device. The BioVolt team built their device from about $2 worth of materials and it can use all kinds of biomass such as leaves and grass clippings as a fuel. The charger is based on using microbes that anaerobically digest the cellulose and then use the products in a microbial fuel cell to produce electricity. The fuel cell doesn't require any precious metals which contributes to its low cost. Unfortunately the device brings new meaning to the term trickle charge. They estimate it would take about six months to charge a cell phone.
[Source: DailyTech, via Engadget]