Biogas & Electric Cuts Emissions from Anaerobic Digesters

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Biogas & Electric, located in San Diego, California, has developed technology that reduces harmful emissions created during anaerobic digestion.

Anaerobic digestion may serve as a renewable energy source, and reduce methane when utilized at wastewater treatment plants, dairies, and landfills. Seth Burns was intrigued by benefits of turning waste to a resource, but realized one of the biggest challenges for the anaerobic digester industry was to reduce the harmful emissions generated by the process.

Stringent standards enforced by the California Air and Resources Board (CARB), and other regional air boards require the reduction of oxides of nitrogen (NOx) emitted during the anaerobic digestion process. NOx is known to cause an array of health problems including asthma.

In an effort to make the anaerobic digestion process more environmentally sound, Mike Matelich, process chemist and inventor of the process, and Burns partnered to develop a way to reduce NOx and SOx emissions.

The technology is an add-on solution to the biogas engine. The add-on puts the biogas engine exhaust in contact with the liquid waste stream from the anaerobic digester.

“Mike determined that certain chemicals are endogenous to the waste stream, such as ammonia, which can scrub the NOx out of the exhaust stream,” stated Burns.

The bench scale prototype chemical reaction that occurs reduces NOx and SOx, the precursors to smog and acid rain respectively, by greater than 95% each.

Burns and Matelich hope to replicate these results in the field at full scale. The following diagram outlines the process:

U.S. Patent No. 8,012,746, entitled “NOx Removal Systems for Biogas Engines at Anaerobic Digestion Facilities,” describes the Biogas and Electric technology (’746 Patent).

According to Burns, a provisional patent application was filed at the end of December 2009. The non-provisional, filed September 15, 2010, enjoyed accelerated examination via the now-defunct U.S. Patent and Trademark Office’s Green Technology Pilot Program (GTPP) (read about some fast track alternatives post-GTPP here). The ’746 Patent issued September 6, 2011, just under a year from the non-provisional filing date.

The company has received funding from USDA-NIFA SBIR Phase I and Phase II research grants and from Waste Management. A full-scale dairy-based demonstration project is being constructed in Imperial County, California. The technology will be utilized on a 300 kW biogas engine.

Previous technologies have only been able to reduce NOx to 9ppm, but Burns and Matelich are confident that their technology will be able to reduce NOx emissions enough to meet the stringent CARB standard of 2 ppm.

Burns and Matelich plan to build a demo project within the wastewater treatment industry, and begin installing their solution for revenue.

Article by Rosemary Ostfeld, appearing courtesy Green Patent Blog.

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About Author

Walter’s contributions to CleanTechies over the past 4 years have been instrumental in growing the publications social media channels via his ongoing editorial and data driven strategies. He is the founder and managing director of Sunflower Tax, a renewable energy tax and finance consultancy based in San Diego, California. Active in the San Diego clean technology community, participating in events sponsored by CleanTech San Diego, EcoTopics, and Cleantech Open San Diego, Walter has also been a presenter at numerous California Center for Sustainability (CCSE) programs. He currently serves as an adjunct professor at the University of San Diego School of Law where he teaches a course on energy taxation and policy.

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