Article written by Cecilia Baldwin
Photography by Don Reid
SACRAMENTO, Calif. – The nation’s first commercial anaerobic biodigester designed by a UC Davis professor is drawing local and global attention for uniting ecology with economy and promoting environmental stewardship.
Ruihong Zhang, a UC Davis professor of biological and agricultural engineering, has been working on the biodigester system for a decade with a pilot stage that began in 2006 on the UC Davis campus.
Zhang’s anaerobic digester technology uses natural microbes to break down organic waste and in the process generates biogas and other forms of renewable energy such as heat, electricity, natural gas, and fertilizer.
The biodigester was completed on a commercial scale in April 2012 after CleanWorld Partners obtained exclusive licensing of the technology from UC Davis and implemented the system at American River Packaging; establishing proof of concept for the Sacramento South Area Transfer Station biodigester construction.
California has three biodigesters; the UC Davis campus where it produces electricity for the university, a second at the American River Packaging in Natomas which produces its own electricity and a third location at the Sacramento South Area Transfer Station.
CleanWorld Partners were awarded the International Bioenergy Project of the Year Award on Dec. 5 and were among the 13 organizations that were recognized last Wednesday with the 2013 Governor’s Environmental and Economic Leadership Award (GEELA), the state’s highest environmental honor.
CleanWorld also received the “Energy Vision’s Leadership Award” for its renewable transportation fuel production and the “Game Changer of the Year Award” for job creation and economic growth efforts.
The Transfer Station’s biodigester is the largest of the three and processes an average of 25 tons a day of mixed corrugated and food waste product from the surrounding Sacramento area.
According to Katie Oliver, an environmental engineer for CleanWorld Partners, once the expansion is complete they expect to quadruple those numbers preventing 100 tons of food waste a day from going into local landfills resulting in fewer greenhouse gas emissions in Sacramento.
Organic waste is collected from local restaurants, supermarkets, hospitals, hotels and food processing companies to be converted into renewable energy; even big box companies like Costco, Campbell’s and Target use the facility to dispose and process their pre-consumer waste.
The station’s biodigester provides clean fuel to the adjacent CNG Fueling Station operated by Atlas Disposal; the fuel is then used to power waste disposal vehicles, school buses and other fleet vehicles.
CleanWorld was awarded $6 million for the biodigester’s expansion in June 2012 through the Alternative and Renewable Fuel and Vehicle Technology Program Award that was created by Assembly Bill 118.
Once the system is upgraded, “the biodigester will produce 700,000 diesel gallons per year of renewable CNG and prevent the release of 18,000 tons of CO2 into the atmosphere,” said the CEO of CleanWorld Partners, Michele Wong in a press release.
The station also “produces 8 million gallons a year of organic soils and fertilizer products for Sacramento area farms and agriculture and generates a million kilowatts of electricity to be used to power the facility and the adjacent Fueling Station,” said Michele.
“The fueling station produces the only commercially available fuel that has negative carbon intensity in the US, meaning it destroys more carbon than it creates,” said Katie.
According to Katie, the City of Sacramento is saving $1 million a year by switching from diesel to the biodigester’s transportation quality methane fuel and the remaining solid waste from the system is separated out and shipped to Davis where it becomes fertilizer sold under the brand name Ecoscraps.