About 2.6 billion people worldwide do not have access to a sanitary toilet. To fix this, the Bill and Melinda Gates Foundation awarded eight grants last year to scientists and engineers to invent a toilet that could function without piped water, a sewer system or outside electricity—and would cost less than 5 cents a day to operate. With the funding, scientists are working on using processes such as evaporation, combustion, pyrolysis and anaerobic digestion to break down waste in toilets into three essential resources: water, fertilizer and fuel.