Thursday, 31 January 2008

Biogas toilets and carbon credits

Here’s a thought for IYS2008, prompted by my colleague at Leeds, Professor Ed Stentiford. In Nepal there’s the Biogas Support Program (project design document here) which is registered with the Clean Development Mechanism (CDM) of the United Nations Framework Convention on Climate Change (UNFCCC). Essentially just under 10,000 biogas plants (typically 4−10 m3) are fed with animal excreta and the biogas produced (equivalent to a total of 14.73 MW of electrical energy) is used for domestic cooking, lighting, heating, etc. The resulting certified emission reduction (CER) is estimated at just under 50,000 tonnes of CO2-equivalent per year (based on the emissions from the firewood and/or kerosene that would otherwise be used and taking into account methane leakage from the biogas plants and incomplete combustion during biogas use). As a result the Biogas Support Program can sell this annual carbon credit of 50,000 t CO2 and the current price is EUR 23 per t CO2-equivalent, so it’s worth quite a lot of money. OK, these biogas plants are fed with animal excreta, but they could be fed with a mixture of human and animal excreta, together with kitchen wastes. So biogas toilets could earn carbon credits and thus hard cash. Wouldn’t this be a useful starting point for rural sanitation promotion, at least in some countries or some parts of some countries? [For more info. see Carbon – Making the right choice for waste management in developing countries (Waste Management, 2008).]