In rural Kenya, pit toilets—basically holes in the ground, with no water for flushing—are the most common type of toilet. They don't always work well. At Maseno School, a large boarding school in western Kenya, the sewer system often backed up and contaminated a nearby stream. And, of course, it didn't smell very good either.
A teenage student at the school came up with a solution: Why not turn the sewage, along with food waste and dung from the school's cattle, into power for the school?
"My inspiration was drawn from the pressing demand for a clean, renewable sustainable source of fuel," says student Leroy Mwasaru, now 17. "In the African continent we have lots of resources that masquerades as 'waste.'"
Along with a team of fellow students, Mwasaru started researching biodigesters—underground chambers that collect waste and use microorganisms to efficiently convert the waste into a renewable fuel. "We were out to make ours more flexible and better," Mwasaru says.
After winning a national competition, Innovate Kenya, for their idea, the students built two prototypes. The second prototype is now in use at the school, sending biogas directly to the school's kitchen, where it provides fuel for stoves. Cooking used to happen on wood fires, a process that sent black soot into the cooks' lungs and stripped local forests of trees.
The same system could also be scaled down to work in individual houses. "After the success of our second prototype I gained enough conviction to build one at our rural home," Mwasaru says. "The blueprint can be retouched based on the target market demands."
The team of students is currently working on another iteration of the design that will separate out liquid waste, since pee can make the process less efficient. Ultimately, they hope to provide the school with plans for a system that can process the waste of all 1,200 students. It will cost around $85,000, but may save half that amount in fuel savings alone.
They hope to eventually launch a startup to bring the system to buildings around the country, based on a sliding scale that will let richer customers subsidize cleaner sanitation and energy for low-income communities.
"After completing high school next year, our team looks to venturing into the project's greatest potentials," Mwasaru says.