Energy and Food Waste are becoming major issues in Africa at present, with warning of dire consequences if the existing trends continue. One technology that sits at the intersection of these sectors is the treatment of processing waste using anaerobic digestion – or biogas.
Biogas is a simple process that is used at household level by millions and is increasingly being used in Europe as part of the sustainable energy drive.
Any organic waste can be fermented in simple ambient reactors over a long period, producing a combustible mixture of gasses consisting mainly of CO2 and Methane. Environmentally, burning Methane is beneficial because it has a hothouse effect some 14 times that of CO2 and is often naturally released by fermenting waste.
The liquid remaining after fermentation is stable and not noxious, even if the waste fed to the process are eg human waste and can be used as a fertiliser.
In household processes gas is used for direct heating and lighting, while in industrial applications is can generate electricity which can be sold to the grid.
There has recently been news of a commercial approach in Canada
Ontario-based StormFisher Biogas is forming partnerships with North American food and drinks firms to allow it to use the organic by-products of farming and food processing operations to produce and sell renewable energy.
“Food processors typically send their by-products to landfills or compost sites. Since we are able to extract more value from these by-products by using the energy they create, we are able to charge a lower disposal fee than landfill and compost sites”.
He added that another advantage afforded processors was environmental stewardship: “This allows food processors to reduce greenhouse gas emissions since the gases that are produced by these by-products are used to create energy, rather then seeping into the atmosphere.”
“When captured and used to generate energy, however, methane serves as an excellent fuel and provides the dual environment benefit of being sequestered from the atmosphere and displacing traditional, polluting forms of energy like coal.”