Large scale human powered Biogas production: A solution whose time has arrived

The average human body produces .696 kilograms of solid waste every day, that's 248 kilograms a year and 18,626 kilograms a lifetime (75). The city of Johannesburg in South Africa was home to 3,225,812 people in 2001, which would mean Joburgers on average produce over 2,245,165 kilograms of solid human waste every day. Waste being the operative word here because that's what we do with it, we waste what is potentially a huge amount of energy and add to global warming at the same time by doing so. To understand how much potential energy is being wasted we must go to prison in Rwanda.

In 1997, The Kigali Institute of Science, Technology and Management (KIST) was formed in Rwanda to address the serious loss of professional manpower. In 2005 it was awarded The Ashden Award for Sustainable Energy for the large scale innovative implementation and use of a biogas system within the Rwandan prisons. The average Rwandan prison holds 5,000 people who together produce 50 m3 of toilet waste water per day. This is waste water is channelled into a 500 m3 capacity biogas system and produces a whopping 250 m3 of biogas per day.

Now although in the Rwandan systems the biogas is almost exclusively burnt for heat energy and accounts thus for a saving of over 60% in wood fuels, it also has the potential to produce electricity through natural gas generators. Approximately .6 m3 of biogas is needed to generate 1 kilowatt-hour (kW-h) of electricity in a gas generator system; this means in a single day one prison of 5,000 people could produce over 416 kW-h. Which bring us back to Johannesburg in 2001 which according to these latter figures could have been potentially producing nearly 161250 m3 of biogas per day or 268,750 kW-h/day. If we take the recent highest monthly electricity consumption for the whole of South Africa which was 20 631 Gigawatt-hours (GW-h) in July 2007, the biogas/electricity from Johannesburg alone could have accounted for 8,331,250 kW-h of that, or roughly 8,33 GW-h or .04% of the national monthly consumption for July at is highest peak. So why is this not the case, why is human and even animal biogas potential not exploited to the fullest extent possible? Are we so prudish and vain as to let this valuable resource literally go down the drain?

Biogas is not a new technology but is has for the most part been sidelined in the face of oil and natural gas resources. Whether

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