Sewage isn’t for dumping anymore. Millions of gallons of raw sewage streaming into the world’s treatment plants have begun attracting a handful of people interested in turning the sludge into an alternative energy source, particularly in developing countries reliant on money-draining oil and gas imports.
Ghana hopes to lead the charge, reports the Christian Science Monitor. Ghana’s parliament has mandated that 10% of the country’s electricity come from alternative sources by 2020 (similar to the state-level goals set by U.S. states like Minnesota, Missouri, and Wisconsin).
Ghana’s renewable energy czar, Kwabena Otu-Danquah, plans to tap one of the country’s more plentiful resources—the 1,000 tons of sewage Ghana dumps into the ocean off the coast of its capital Accra every day—by building its first "fecal sludge-fed biodiesel plant." The facility will essentially cook human excrement into biodiesel.
For decades, methane from decomposing organic matter in sewage has been captured to generate power. Now techniques to turn raw sewage directly into liquid fuels are making that a viable source of energy. Research in the journal Environmental Science & Technology this September reports that sewage yields cheaper biodiesel (it’s derived from fats rather than algae or soybean oils): $0.03 for a liter of lipids extracted from sludge compared to soybeans at $0.80.
Cost and engineering barriers still exist. The biofuel from the sewage plant may cost about $7 per gallon, but the Ghanian firm Waste Enterprisers—backed by $1.5 million from the Bill & Melinda Gates Foundation—intends to sell the fuel to commercial customers who are also bound by the 10% goal and build four more plants in Accra if the pilot is successful.
If Africa is going to build a green power grid, it will have to turn its cheapest waste into some of its most valuable resources.