Ghana's best shot at going green: sewage power
With solar and wind power costly and inadequate, Ghanaians are turning to some very alternative sources of energy – like human waste.
How might the world's poorest continent go green? Kwabena Otu-Danquah's job is to crack that riddle. The renewable energy czar for Ghana ranks among the handful of bureaucrats across Africa tasked with picking which forms of green energy might prove affordable on a continent where most people don't pay for the electricity they sometimes receive.Skip to next paragraph
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Last year the Ghanaian Parliament signed a pledge to derive 10 percent of the country's electricity from alternative sources come 2020. Mr. Otu-Danquah is still trying to figure out which alternatives.
Sun? Forget it. Solar costs 40 to 50 cents a kilowatt-hour, while Ghanaians pay just 5 to 10 cents for electricity from conventional sources. Wind? Too slow. Breeze ambles through this tropical doldrum at a leisurely average of five kilometers an hour (3.2 miles per hour). How about jatropha, a local flower Goldman Sachs pitched as the next fad biofuel? Ghana tried that. As growers mowed down farms to plant nuts for fuel, drought-battered countries to Ghana's north complained of food price spikes in some of the world's hungriest villages.
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That's forced Ghana to consider a more imaginative set of choices. Among them, sewage. Flush with a $1.5 million grant from the Bill & Melinda Gates Foundation, local Waste Enterprisers Ltd. is building Ghana's first "fecal sludge-fed biodiesel plant." That's longhand for cooking human excrement into generator fuel, chief operating officer Tim Wade explains. The transformation would serve a dual purpose. Open sewers sweep 1,000 tons of slurry each day into the ocean off Accra, spewing an ocean-top brown slick that is visible on Google Earth. Outside the upland city of Kumasi, roughly 100 trucks dump tens of thousands of liters of septic tank sewage daily into what used to be a small pond.
Luckily, nobody bothers to treat that slop. Sewage treatment plants, as far as Mr. Wade is concerned, fritter away the good stuff. If all goes according to plan, next month one truck a day from Kumasi will dump its payload into a warm and massive vat that will skim lipids – fat – off the top. “That's your biodeisel,” he explains.
At $7 a gallon, he can sell the muck to local mining companies, who are keen to buy because they, too, have been required by Parliament to power 10 percent of their private electric plants from green sources. Normal diesel does sell for a few bucks cheaper, he admits, “But we're still optimizing the process.” If he can get costs down, Wade intends to build four plants in Accra and lecture subdivisions back home in Colorado on the folly of treating their waste.