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An early prototype of the Walker Wellington turbine.
Wednesday, November 21, 2012

Making electricity from the outflow pipe of a sewage plant

The state has just announced seven renewable energy projects to be partly funded from the Renewable Energy Fund, which gets money from utility companies as part of the state's push to diversity our energy supply. (More details here.)

The most interesting announcement involves a prototype of a hydropower generator that will be installed at the outfall pipe of Dover's wastewater treatment plant. It's a special turbine developed by a Portsmouth company called Walker Wellington, that is engineered for low head (i.e., the water doesn't fall very far), variable-flow applications, unlike the situation you get in a hydropower plant on a river dam.

The company got $100,000, out of $129,000 total cost, for a 20 kilowatt unit - not much by utility standards, admittedly, but every bit helps. The inventor says its variable-pitch blades allow the turbine to work when most wouldn't.

Turning various bits of unavoidable waste into usable energy is part of the approach we need to take; combined heat-and-power plants, which make use of excess heat generated by electricity-generating facilities, are the most obvious example.