SONOMA -- The California Municipal Finance Authority approved $35 million in low-interest bond financing for a planned multi-megawatt renewable-energy project next to the Sonoma Valley wastewater treatment plant in the industrial area south of Sonoma.
Called Farms to Fuel, the plant would take in mainly chicken manure as well as some dairy and winery crushpad organic waste and produce methane, used to produce electricity and natural gas, as well as odorless, sterile fertilizer, according to John Naab, a Sonoma resident, former Napa Valley commercial real estate developer and director of Western U.S. operations for Kansas City, Mo.-based BioStar Systems.
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"Sonoma County is the most progressive county for green alternative energy we could find in the country," Mr. Naab said.
Sonoma BioStar LLC is one of several agricultural biodigester projects BioStar Systems has in various stages of funding and government approval in Ohio, Texas, Wisconsin, California and other undisclosed locations, he said. Each are estimated to cost about $30 million and are being pursued in locales with financing help for renewable energy projects.
BioStar's biodigesters use anaerobic bacteria to break down the organic waste in an oxygen-free environment. Gas produced in the process is mostly methane and is captured in the enclosed reaction chambers rather than being released into the air, as with traditional composting. This biogas is prepared to use in fuel cells to produce electricity or compressed natural gas.
Also using biogas to create energy are a number of dairies such as Straus Family Creamery in Marin County and wineries such as Clos du Bois in Geyserville.
BioStar is focusing on chicken manure because much of the nutrient value that anaerobic bacteria can consume to produce methane survived the birds' digestive tract, Mr. Naab said. A chicken may leave 90 percent per pound of feed, while bovines use their multichambered stomachs to break down most of it.
Existing and looming state and federal clean air and water regulations could make biodigesters a lucritive investment. Spreading manure on fields has been an agricultural practice from ancient times, but regulators increasingly are cracking down on how it's used because of potential for rainwater to carry nitrogen and phosphorous into fish habitat in nearby waterways as well as the potential for released methane to impact public-policy efforts to control smog and climate change.
The possibility of converting diesel engines to use compressed natural gas and the availability of more methane-moved passenger cars are expanding potential markets for biogas too, Mr. Naab noted.
Another possibility would be a deal with the County of Sonoma to provide electricity to power the adjacent electricity-hungry wastewater treatment plant, he said. The proposed plant would produce between 1.4 and 5.6 megawatts of electricity.
"Once the plant is built, it can have a fixed cost over 20 years and could save the county millions of dollars in energy costs," Mr. Naab said.
No project application has been submitted yet, and it's not yet known what level of environmental review will be needed for the project. The state bond financing now allows Sonoma BioStar to hire engineers, architects, contractors and other consultants to prepare documentation.