Ghana's best shot at going green: sewage power

http://www.csmonitor.com/Environment/2012/1003/Ghana-s-best-shot-at-going-green-sewage-power/%28page%29/2

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.

By Drew Hinshaw, Correspondent / October 3, 2012

Accra, Ghana

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.


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 cents to 50 cents a kilowatt hour,
while Ghanaians pay just 5 cents 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.

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 and
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, frivol 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 sells a few bucks cheaper, he admits, �But we're
still optimizing the process.� If he can get costs down, Mr. Wade
intends to build four plants in Accra and lecture sub-divisions back
home in Colorado on the folly of treating their waste.

Alternatives to the alternatives

There are more sanitary ways to make a megawatt in this country. Kwame
Tufor came home from Florida to liquefy Ghana's coconut husks, cocoa
pods, and palm nut shells into gas. But you'd need a lot of coconuts
to turn a profit that way. So he and a business partner are eyeing an
old paper farm the size of Brooklyn. Sometime between one 1970s coup
and another, the owner ran out of money and political favor,
abandoning acres of trees that were meant to be mulched into notepads
35 years ago.

Mr. Tufor intends to saw those trees down, replant them, then burn
the timber and compress the smoke into a biofuel using dated World War
II technology that's been dusted off by developing world power plants.
At least 10 plants in China now gasify coal this way. Farmers in the
Philippines run irrigation pumps on generators that gasify rice husks.
If Mr. Tufor's $200 million project pans out, local farmers would also
sell him their nut shells and cocoa pods for his incinerator.

Odder sources of energy are under review. They include leftovers.
Ghana's trash, it seems, boasts curiously high food content � edibles
account for 60 percent of this country's rubbish, according to Senior
Researcher Robert Adu at England's De Montfort University, Leicester.
He's finishing a technical proposal on how to goose a charge out of
Ghana's garbage. One thing Ghana's got going for it: Locals love rice.
One kilogram of the staple grain, Mr. Adu says, packs 17 kilojoules, a
flicker compared to a kilo of kerosene, but great compared to a
vegetable.

Subsidizing trash

Ghana's government offers a subsidy for companies that can produce
renewable energy at a cost closer to the African pay scale. For Mr.
Adu, that means it might just be profitable to feed tons of rotten
groceries everyday into a fire that would boil a tank of water whose
steam would lurch a turbine forward. The trouble? How to cull the grub
from the garbage. Trash separation schemes do exist; Mr. Adu says he's
reading a book on them. He points to a plant in Germany that's
mastered the technique through a process made profitable by sales of
hot air, a byproduct, to heat homes in wintertime. If Mr. Adu goes
that route, he'll have to find buyers looking to purchase hot air in
the tropics.

Mr. Otu-Danquah isn't quite sure will this burst of invention will
wind up: At the day's end, economics on what Ghanaians and their
government can afford will surely dash some dreams. But the proposals
make for more interesting reading, he says, than the stack of
hackneyed solar plant schemes he's stuffed into a corner. Plus, some
big break just might occur.

�When the time comes,� he says. �we will have learned our lessons and
developed our own technology.� At the very least, he adds, Accra might
enjoy cleaner streets, cleaner sewers.
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