Biogas: Poo-Powered Prison in Rwanda

Our friends are WorldChanging link to very interesting posts from the Timbuktu Chronicles. Emeka Okafor wrote about an excellent example of how to use biogas: The Kigali Institute of Science and Technology's Center for Innovations and Technology Transfer (Kigali is the capital of Rwanda) designed and built a 150 cubic meters fixed dome digester in Cyangugu prison. The digester is fed human waste generated by 1500 prisoners and it produces 50% of the energy needed to cook for the 6000 to 10,000 inmates (the number vary depending on the source), cutting in half the £25,000 ($44,000) yearly firewood bill - a lot of money in Rwanda. I'm not sure why the digester doesn't get the waste from all prisoners, but the simple answer probably is that it's simply too small for that, which would mean that with expansion the firewood bill could be eliminated.The Kigali Institute of Science and Technology has also built a smaller digester (25 cubic meters) for the Lycée de Kigali, solving its sewerage and hygiene problem. "The methane gas produced is used to cook for 400 students and for operating bunsen burners in the school science laboratories..."

Five of the country's largest prisons - two at Gitarama, and one each at Butare, Kigali and Cyangugu - now boast biogas plants, either in operation or under construction, and their effect has been dramatic. [...]

Biogas doesn't sound the most pleasant of energy sources - either in sight or smell. But for anyone who's not seen one in operation, the result can be surprisingly attractive. All the guts of the system are tucked safely out of sight underground. The gas produced burns with a clean, blue smokeless flame - in contrast to the wood which it's replacing. And the residue makes excellent, odour-free compost: a thick treacle of dark grey muck which enriches the prison's gardens, growing maize, mangos, bananas and tomatoes, and in some prisons, fuelwood trees, too.


The prison officers at Cyangugu were understandably proud of their scheme: they'd taken the soil excavated from the biogas pits, and used it to make two gardens: small, peaceful oases of flowers and shrubs in the heart of the prison.
::KIST Rwanda , Biogas, ::KIST Rwanda, Biogas Award, ::Ashden Awards 2005, via ::WorldChanging