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Published on December 15th, 2012 | by Tina Casey


Largest “Stomach” In The U.S.A. Digests Food Waste, Spits Out Biogas Fuel For Trucks

December 15th, 2012 by  

The company CleanWorld has just started up what could be described as a gigantic man-made digestive system at a garbage transfer station in Sacramento, California. When it’s fully expanded, the Sacramento Biodigester will be the largest facility of its kind in the U.S., capable of gobbling up about 100 tons of food waste per day and converting it into enough natural gas fuel to replace 1 million gallons of conventional diesel fuel per year — and that’s just for starters.

Sacramento will get biggest food waste biodigester in the US

The Skinny on the Sacramento Biodigester

The new digester basically employs the natural process of anaerobic digestion to break down organic material, only it’s revved up and precisely balanced to achieve a high level of efficiency on a truly massive scale (anaerobic digestion refers to bacteria that thrive without oxygen). The process yields both renewable biogas and inert solids that can be safely used as a fertilizer or soil enhancer.

Anaerobic digesters are becoming commonplace at sewage treatment facilities, where the waste stream is essentially a liquid containing very low levels of solid material. The particular challenge faced by CleanWorld has been to develop a cost-effective process for waste streams containing high levels of solids.

CleanWorld’s proprietary process was originally developed over a span of ten years at the University of California–Davis. The company first caught our eye last May, when it developed a digester system for the company American River Packaging. At 7.5 tons of waste per day, though, that system is peanuts compared to the Sacramento Biodigester.

One Waste Stream, Many Benefits

Biodigesters are familiar ground to regular readers of CleanTechnica, since we’ve been regularly following the Obama Administration’s championship of anaerobic digesters for livestock manure through the Agstar program.

In livestock operations, digesters give farmers a sustainability twofer by turning a huge liability (raw manure) into valuable products (low-cost energy and soil enhancer) that they can sell or use on site.

Similarly, the Sacramento Biodigester turns a gigantic 100 ton-per-day food waste liability into useful products. Though the transfer operation isn’t set up to handle household waste, it will take in waste from food processors, restaurants, and supermarkets.

Part of the aforementioned natural gas produced by the new digester will go to a fueling station at the site. Currently under development by Atlas Disposal Industries, this will be the first renewable biogas (via anaerobic digestion, that is) station in California.

There will be enough gas to fuel Atlas Disposal’s trucks and generate electricity for the fueling station, which will apparently make it the first anaerobic digestion biogas-powered fueling station in the U.S.

There will also be plenty of gas left over for natural gas vehicles owned by other agencies in the area.

In addition to the biogas, the facility will also yield organic solids that can be used as fertilizers and soil enhancers by local farms.

We Built This!

Not to rub it in, but what the heck. When you hold a public office or campaign for one, you take on a civic responsibility that should offer at least a passing nod to reality, and the reality is that the U.S., like all developed countries, has always been and will always be developed by a working relationship between the taxpaying public and private enterprise. We’re all in this together, right?

So here’s a shout-out to all the partners that made the Sacramento Biodigester happen. Aside from long-term foundational research support through California’s public education system, the project was financed and developed by: Synergex, Five Star Bank, Central Valley Community Bank, California Energy Commission, CalRecycle, California Office of State Treasurer, Otto Construction, Atlas Disposal, City of Sacramento, Sacramento County, Sacramento Municipal Utility District, Sacramento Metropolitan Air Quality Management District, Carson Development Company, Peabody Engineering, TSS Consultants, Capstone Turbine Corp., and the engineering firm Frank M. Booth.

Image: Food by sampsyo

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About the Author

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+.

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