What alternative energy source powers a new bus in London?

The U.K.’s first bio-bus is powered by the methane gas generated from the treatment of its primary power source: human poop and food waste. The bus can travel 186 miles on a full tank of fuel and generates 30 percent less pollution than a diesel powered bus. Those worried about the smell of emission were comforted to learn that the treatment process eliminates the impurities that cause odor. CNN estimated that biomethane production from sewage, already used to heat homes in the U.K., could replace about 10 percent of the nation’s domestic gas needs if all waste were to be utilized.