turn this tide, Kamen designed the Slingshot, a vapor compression distillation system powered by a Stirling engine—or, a water purifier the size of a mini-fridge capable of running off any combustible fuel, including dried cow dung. Using less electricity than required to power a hair dryer, the Slingshot can purify water from any source: polluted groundwater, saltwater, sewage, urine, take your pick. One machine provides clean drinking water for three hundred people a day; a hundred thousand machines—now that’s the kind of cooperative effort we’re talking about.
