WHERE there’s muck, there’s brass—or so the old saying has it. The cynical may suggest this refers to the question of who gets what, but thoughtful readers may be forgiven for wondering, while they are recovering from the excesses of Christmas in the smallest room in the house, what exactly happens when they flush the toilet.
The answer is encouraging. Less and less waste, these days, is actually allowed to go to waste. Instead, it is used to generate biogas, a methane-rich mixture that can be employed for heating and for the generation of electricity. Moreover, in an age concerned with the efficient use of energy, technological improvements are squeezing human fecal matter to release every last drop of the stuff. Making biogas means doing artificially to faeces what would happen to them naturally if they were simply dumped into the environment or allowed to degrade in the open air at a traditional sewage farm—namely, arranging for them to be chewed up by bacteria. Capturing the resulting methane has a double benefit. As well as yielding energy, it also prevents what is a potent greenhouse gas from being released into the atmosphere.
The consequence of techniques such as these is that an ever-larger proportion of sewage is being used as a raw material for energy generation. Germans already process about 60% of their faeces this way, and the Czechs, Britons and Dutch are close behind (see chart). GENeco reckons the figure in Britain by the end of 2010 will have leapt to 75%—enough, when converted into electricity, to power 350,000 homes. And the latest thinking is to improve yields still further by cutting out the middle man. Faeces are food that has been processed by the human digestive system to extract as much useful energy as possible. An awful lot of waste food, though, never enters anyone’s mouth in the first place, and this is an even more promising source of biogas.
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