Nowadays we can produce electricity from sewage. In the future, the waste water from your sink, bathtub, and toilet may do more than just go down the drain. It may become a source of electricity tomorrow. The bacteria naturally generate electrons as they break down organic materials. A fuel cell siphons off these electrons to create an electric current.

A fuel cell powered by naturally occurring bacteria has successfully converted 13 per cent of the energy in sewage to electricity – and cleaned the waste water at the same time. It's hoped genetic engineering could make this much more efficient.