4. Human Waste

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Yes, by “human waste,” we are talking about what you are already thinking. It’s true that both feces and urine can be utilized to create energy. Feces, when left to its own devices, can produce methane gas, which can be burned to produce energy that could be used for any number of things. And although we might not think of “number one” as the number one way to produce energy, there is some promise of generating energy with urine. Researchers at the Heriot-Watt University’s School of Engineering and Physical Sciences in Edinburgh are currently experimenting with ideas that may lead to a fuel cell powered by urine.