?Energy from waste? or waste to energy by biological conversion ? by high solids anaerobic digestion - is the most promising use of bioenergy from all renewable organic material in residues and waste. Human excreta mixed with renewable organics in household waste contain about 3000 kWh energy per tone. At least 1000 kWh can be converted to methane in biogas but with improvements of present system even more can be used as biogas. Part is lost during process but huge amount is left in biofertilizers together with all plant nutrients and beneficial microorganisms. Biofertilizers can replace artificial fertilizers and improve both soil fertility and food quality.
500 people in western countries produce about one tone of such mixture per day. Then can be added all renewable organic materials from parks, gardens, etc. Local facilities can produce biogas for local use and biofertilizers for growers of crops for food and for bioenergy.
Dogs in a Boston park have made the news lately by lighting up a single lamppost with their droppings.
But this week, the English have taken the poop-for-power concept further by connecting it to their national grid. About 200 homeowners now heat their residences and cook their meals via human feces—their own, their neighbors’, probably some other folks’.
They aren’t, of course, burning the excrement itself, but the biomethane resulting from the anaerobic break down of the waste by bacteria. The biogas is treated before being fed into the grid, and there is no discernible difference (odor, for instance) from other gas used for central heating and stovetops.
While Britain gets much of their renewable electricity from wind energy, customers can now enjoy a renewable form of gas. From flush to flame, the recycling process takes about 3 weeks.
Martin Baggs of Thames Water in a statement:
We already produce £15m a year of electricity by burning biogas from the 2.8bn litres [7.4bn gallons] a day of sewage produced by our 13.8 million customers. Feeding this renewable gas directly into the gas grid is the logical next step in our ‘energy from waste’ business.
In case you were wondering, each year the average person makes 66 pounds of this sludge (dried). That could power a lot of lampposts! British Gas says the sewage drawn from the entire British population would serve the gas needs for about 200,000 homes, reports The Independent.
But for now, it’s a pilot project, costing about $4 million, taken on by British Gas, Thames Water and Scotia Gas Network. A similar effort is in the works by United Utilities in Manchester for next summer.
Related on SmartPlanet:
- Toilets in Skyscrapers: energy source?
- California laws becoming ‘dairy digester’ intolerant
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Image
: Flickr_forbesphotographer and Park Spark
Via: The Independent
