University of Nevada Develops Biofuel from Sewage Sludge

September 23rd, 2010 by Tina Casey

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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Tags: sewage sludge, Truckee Meadows, University of Nevada at Reno, Wastewater

About the Author

Tina Casey Tina Casey specializes in military and corporate sustainability, advanced technology, emerging materials, biofuels, and water and wastewater issues. Tina’s articles are reposted frequently on Reuters, Scientific American, and many other sites. Views expressed are her own. Follow her on Twitter @TinaMCasey and Google+.

Guest

It’s misleading to include the term “biofuel” in this article; the final energy form is electricity, and not a transportation fuel, as the term “biofuel” implies.
- Bob_Wallace
  
  Oil used to run a diesel generator is not fuel?
http://Yahoo.com Name (required)Lawrence Landherr

Only in Nevada (or the desert SW will this ever be energy efficient. Using sun provided heat energy to dry the sludge gives a net return in excess of energy inputted. If you Energy Return isn’t more than you Energy Input this approach is a total failure.
- Tina Casey
  
  Lawrence: I agree with the general (and obvious) point that the process must be cost-effective in order to succeed. The process was designed for high efficiency, including waste heat reuse, so although solar and other renewable energy may be preferable, depending on the cost of other available methods of sludge disposal it’s also possible that running the process on conventional fuel may be a cost-effective means of managing sludge at some treatment plants.
Eric Higgins

I’m happy to see gasification processes such as these starting to gain more public attention. However, I dare say – these Reno guys are a little behind the game as far as waste-to-energy goes. The process their using – pyrolytic gasification – can actually be used to process any carbon based material (organic or synthetic) into usable fuels. A large number of companies have already run commercial pilot programs including Envergent Technologies (who also use a fluidized bed approach). It’s cool stuff… but there are still a few hurdles… partcularly when you start infusing sand like these guys do…