A quarter of the people in the world still drink filthy water and live miles from electrical power; nearly half the world lacks sewage treatment. Environmental engineer Bruce Logan and his team at Pennsylvania State University are working to remedy all three problems at once. They have created a fuel cell that uses wastewater to generate electricity—and spits out pure water in the process.
The essential ingredients are bacteria that feast on sewage. Such bacteria, commonly used in commercial wastewater treatment, can act as little power plants. “When bacteria break down a compound, just like when you and I eat, they oxidize the compound and derive energy from it,” Logan says. The oxidation process liberates electrons, which he harvests in the fuel cell to produce a small electric current. Logan’s teacup-size prototype can generate enough electricity to run a small fan. Within a year or two, Logan predicts, the Penn State team will have an expanded fuel cell—about the size of a filing cabinet—that can process a gallon of water a minute and power a standard household refrigerator.
Although there are many other ways to produce electricity and clean water in undeveloped areas, Logan notes that sanitizing wastewater usually consumes power; in this case, it generates power instead, potentially making the bacterial fuel cell a more economical option. “This has huge implications globally,” he says, “because there are a billion people who lack adequate sanitation.”