A team of researchers from the University of Nevada at Reno is out to prove that sludge from a wastewater treatment plant can be dried, powdered, gassified as biofuel, and then burned to generate electricity, which in turn can run equipment at the same treatment plant. Talk about having your cake and eating it, too! The question is whether the researchers can make their sewage sludge-to-biofuel process operate at a cost low enough to compete with the price of conventional fuels.
From Sewage Sludge to Biofuel
The University of Nevada team has come up with at least part of the answer. Sewage sludge, as its name implies, is a liquid, and normally it would take an enormous amount of energy – or a lot of space and time – to dry it into powder form. To accomplish the task economically, the team built a processing machine based on a bed of sand and salts, which can be operated at a relatively low temperature. Waste heat from the process is also reclaimed to generate electricity. It should also be noted that processing sludge on site also saves a great deal of energy, compared to trucking it off site for disposal, which would help make the cost of running the system overall more competitive.
Wastewater In, Renewable Energy Out
CleanTechnica covered the startup of the project last spring at the Truckee Meadows Water Reclamation Facility, and so far, so good. The equipment, which is only the size of a refrigerator, is processing about twenty pounds of sludge an hour, which yields about three pounds of dry powder. When scaled up, the team estimates that the system could generate 25,000 kilowatt hours daily. And if that’s not enough, some wastewater treatment plants are already beginning to install solar energy, which could be used as a supplement.
Image: Sewage sludge by robbie1 on flickr.com.
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