How can we get power from poo?

11 July 2013



How can we get power from poo?


Hannah - So, should we lay cables courtesy of the colon? First up, we asked Dr. David Waltner-Toews, author of the Origin of Faeces, is it possible to go fracking for faeces?

Waltner - The energy content of dry manure is about 50% that of coal. Right now, the most efficient way to get that energy is to run the manure to something called an anaerobic biodigesture. So, the manure is running to a contraption where certain bacteria in the absence of air will capture methane from the manure which would otherwise be just released into the environment. That methane can then be burned directly. It can be burned for running trucks, for running machinery, or it can be used to generate energy in a secondary process.

Hannah - So, it is possible to get power from poo. Do we currently actually do it though? We delve into the data.

David - My name is David MacKay. I'm the author of Sustainable Energy Without the Hot Air. I'm the Regius Professor of Engineering at the University of Cambridge and I'm the Chief Scientific Adviser at the Department of Energy in Climate Change. Looking back in 2006, one of the biggest forms of renewable energy in the UK was collected from methane gas coming from landfill sites and from sewage. The scale of this in 2006 was about 0.3 kilowatt hours per day per person coming from all forms of waste and that made it the biggest renewable at that time. Since then wind has overtaken incidentally. How does that compare with total energy consumption? Well, total energy consumption in all forms for transport heating and electricity is about 125 kilowatt hours per day per person. So, we do produce power from poo, but it's not as big as our total power consumption at all and there's no way it could be that big either because if you think about how much food you eat, the energy in the food you eat is about 3 kilowatt hours per day per person. Obviously, the energy coming out in your poo has to be a bit smaller than that.

Hannah - So yes, poo does produce power, but we currently consume more energy. So, also look at the wind amongst other places for other sustainable sources of power. Well, making a movement with our next question.


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