Three of the four inventors of the urine-powered generator (Eric Hersman)Four African girls have created a generator that produces electricity for six hours using a single liter of urine as fuel. The generator was unveiled at last week's Maker Faire in Lagos, Nigeria, by the four teens Duro-Aina Adebola, Akindele Abiola, and Faleke Oluwatoyin, all age 14, and Bello Eniola, 15. So how exactly does the urine-powered generator work? Urine is put into an electrolytic cell, which separates out the hydrogen. The hydrogen goes into a water filter for purification, which then gets pushed into the gas cylinder. The gas cylinder pushes hydrogen into a cylinder of liquid borax, which is used to remove the moisture from the hydrogen gas. This purified hydrogen gas is pushed into the generator. And as for delivering the fuel itself? Well, we'll leave that up to the consumer. The Maker Faire is a popular event across the African continent, drawing thousands of participants who travel to Lagos to show their inventions and other practical creations. As the Next Web describes it, the Maker Faire is intended to highlight creations "that solve immediate challenges and problems, and then works to support and propagate them. Put another way, this isn't just a bunch of rich people talking about how their apps are going to change the world."