Daniel_Stuckey writes "With funding from the Bill and Melinda Gates Foundation's Reinvent the Toilet challenge, [a] team has developed a toilet that uses concentrated solar power to scorch and disinfect human waste, turning feces into a useful byproduct called biochar ... a sanitary charcoal material that is good for soils and agriculture. By converting solid waste to biochar (liquid waste is diverted elsewhere, as it's easier to deal with), the toilet thus allows for sanitary waste disposal without huge infrastructure investments. The toilet itself, called the Sol-Char, is a fascinating bit of engineering. In order to sanitize waste without the help of massive treatment facilities, Linden's team instead designed the toilet to scorch waste in a chamber heated by fiber optic cables that pipe in heat from solar collectors on the toilet's roof. 'A solar concentrator has all this light focused in on one centimeter. It'd be fine if we could bring everyone's fecal waste up to that one point, like burning it with a magnifying glass,' Linden said. 'But that's not practical, so we were thinking of other ways to concentrate that light.'"