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Clean Power A new co-generation project at a sewage treatment plant in Washington State will save energy and reduce greenhouse gas emissions

Published on May 4th, 2010 | by Tina Casey

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Saving the World, One Sewage Treatment Plant at a Time

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May 4th, 2010 by
 
A new co-generation project at a sewage treatment plant in Washington State will save energy and reduce greenhouse gas emissionsA new $2.4 million biogas and energy efficiency project at a sewage treatment plant in Washington State will capture methane gas from the treatment process and recycle it as fuel to run equipment at the plant, saving the sewage agency more than $228,000 yearly in utility costs.  That’s a pretty decent payback, especially since $1.7 million of the total was chipped in by Puget Sound Energy, the local utility company.  Along with the efficiency upgrade, the biogas project will greatly reduce greenhouse gas emissions from the treatment plant and save about 2.8 million kilowatt hours yearly (enough to power about 210 homes), relieving pressure on the local grid and helping to obviate the need for new fossil fuel burning power plants in the region.

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The project, which is located at the Budd Inlet Treatment Plant, is just one of a veritable flood of new methods for reclaiming valuable resources from what is, let’s face it, the ultimate renewable energy feedstock.  Perhaps before we go any farther with high risk energy sources such as deep sea oil drilling we should more fully exploit the riches at hand.

Biogas and Energy Efficiency

The Budd Inlet project is a cut above the run-of-the-mill biogas retrofit because it also incorporates a significant energy efficiency upgrade.  Methane biogas is generated from the natural processes in which microorganisms digest organic matter.  To make the process operate more quickly and efficiently, sewage treatment plants use aerating equipment to pump more oxygen into the wastewater.  The Budd Inlet plant is receiving new aeration equipment that is expected to save more than $48,000 of the total in utility costs.  Also, in addition to running equipment at the plant (which also includes a water resources education center), the biogas project will provide heat and energy for a new children’s museum next door.

Old Energy, New Energy

The utility company that provided the grant for the system is Puget Sound Energy, which is the oldest energy utility in Washington State.  Old age hasn’t stopped the utility from plunging ahead with new sustainable energy technology for the future.  In doing so it is pushing a significant trend toward reclaiming human and animal waste for renewable methane, including biogas from cows, biogas from pigs, and biogas from food processors.  The resource recovery potentials also include bioplastics and biofuel.

The New Sewage Treatment Gold Rush

In addition to the waste recover potential, many sewage treatment plants are ideal sites for solar power installations: large parcels of flat land with no tree shade or other sun blockage.  Also, sewage treatment plants are all about managed flow, which could make them potential sites for small scale hydrokinetic turbines that capture energy from moving water.  Sure, “Retrofit, baby, retrofit” isn’t as catchy as “Drill, baby, drill,” but I think at this point we’d all like to dump the idea of making energy policy by catch phrase and just start doing things that make sense in the real world.  Those billions that will be spent on cleaning up British Petroleum’s oil spill in the Gulf Coast sure could have bought a lot of retrofits.

Image: Sewer manhole by St_A_Sh on flickr.com.

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About the Author

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+.



  • http://www.digivu.co.za davve

    I’m a bit worried that you article could leave people with incorrect perceptions about biogas.

    Its a very old technology not a “new sustainable energy technology for the future” there are millions of plant in operation around the world mainly at homestead but also at industrial level and originates in the 19 century if I remember correctly. Since its so effective lets hope it does become a technology of the future.

    Biogas is produced by the anaerobic (without air) fermentation of organic waste, so the aeration definitely doesn’t make the biogas process run faster. I assume it improves other parts of the process which improve the integration between sewage treatment and biogas production.

    • Tina Casey

      Agreed, and I think I mentioned that in the post…reclaiming biogas from municipal sewage treatment plants is nothing new, but the technology is still developing and until recently it was something of an afterthought, not standard operating procedure. Also yes, the improved aeration from the new blowers resulted in energy savings from other parts of the treatment process, not the biogas part.

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