Published on March 24th, 2010 | by Tina Casey0
Countdown to "Free" Renewable Energy from Sewage Begins
March 24th, 2010 by Tina Casey
They prefer to call it wastewater, but the bottom line is that researchers at the University of Nevada are close to commercializing a process for generating renewable energy from sewage sludge. The energy could be used to run equipment at the plants, which is a big deal because sewage treatment plants (okay, so wastewater treatment plants) are massive energy consumers. Operations like pumping and aerating, skimming off trash, separating grease, drying sludge, and disposing of sludge have a huge carbon footprint, especially when you get into big-city treatment systems that handle hundreds of millions of gallons daily.
Nationwide, that activity adds up millions of tons of greenhouse gases which could be neutralized by sewage-to-electricity technology. It could also help reverse the relationship between cities and energy; they will produce a good chunk of the energy they use instead of importing it, using wastewater treatment plants and other infrastructure as inexpensive clean energy generators that help keep local budgets manageable while reducing air pollution and greenhouse gases.
The University of Nevada project will be set up at the Truckee Meadows Water Reclamation Facility, which serves the cities of Reno and Sparks. They hope to have the system up and running in May. In a continuously cycling process the system will dry sludge (the organic byproduct of sewage treatment) into a solid fuel that could be used in a gasification process, and converted into electrical energy. In addition to generating electricity, the process would significantly reduce the cost of trucking sludge off site for disposal. The researchers estimate that a single full scale facility could generate about 14,000 kilowatt hours daily.
Mining the Potential of Sewage Sludge
The potential for renewable energy generation from sludge on a national level is enormous. The researchers estimate that California alone generates approximately 700,000 metric tons of dried sludge every year, enough to yield 10 million kilowatt hours daily. Access to inexpensive, renewable (and reliable) energy will become even more important because the cost of sewage treatment is bound to rise (there are a variety of reasons for that, including stricter environmental regulations). Electricity from sewage sludge isn’t entirely free of course, but the feedstock is free through the generous contributions of numerous small donors. With the addition of solar energy installations and other renewables at treatment plants, sewage-to-energy could at least help keep costs manageable.
Support Your Friendly Neighborhood Sewage Plant
Seriously, we ought to be way past the ick factor when it comes to exploiting the abundant riches of municipal sewage. It truly is a renewable, reliable feedstock and it can be harvested quite easily through existing infrastructure (aka sewers) without blowing up pristine mountains. Among the new sewage resource developments to look out for are a bacteria that could directly convert sewage to electricity, a method for making bioplastics from sewage, and biogas recovery. The treated effluent from sewage treatment plants, which used to be shunted into the nearest waterway, is now being used to irrigate golf courses and recharge aquifers. The U.S. Navy is even getting into the act with a test-run of a portable wastewater recycling system. Reclaimed water from the system meets drinking water standards but for now the Navy uses it to flush toilets and perform maintenance tasks. Waste not, want not, right? Go, Navy!
Image: Sewage by Elsie esq. on flickr.com.