February 22, 2011 | General

Anaerobic Digest

BioCycle February 2011, Vol. 52, No. 2, p. 15

Dane County, Wisconsin
The first “community” anaerobic digester facility in Wisconsin began operating December 16, 2010 in Dane County. The digester was built in the Town of Vienna and is processing manure generated by Ripp’s Dairy Valley farm, White Gold Dairy and Richard Endres Farm. The digester was designed and built by Clear Horizons LLC in Milwaukee, which will also own and operate the facility. Construction began in August 2010. Nearly $2 million/year worth of electricity will be produced, enough to power 2,500 homes. The three 1-million gallon digester tanks each take about two weeks to initially fill. The Vienna facility is expected to begin producing electricity for sale to Alliant Energy in February.
Four dairy farm families in the Town of Springfield, Wisconsin are working with the county and Clear Horizons to develop a second digester which will also be built and operated by Clear Horizons. The company is working with the county and the four town of Springfield farms to develop a design and schedule and identify the best site and layout.
Dane County (population 453,000) is Wisconsin’s second largest county. Its $700-million dairy industry, which employs 4,000 people, includes 400 dairy farms that milk 50,000 cows. Those farms produce more than two billion pounds of manure annually. The digesters are designed to remove most of the phosphorus in the manure, which will reduce algae-growth and pollution in local lakes and streams. Total costs of building and installing the two digesters is approximately $24 million. The state of Wisconsin is providing $3.3 million for each project; the remainder is being funded by Clear Horizons.
Washington, D.C.
U.S. Secretary of Agriculture Tom Vilsack announced in late January that biofuels and biomass energy projects across America have been selected for funding to continue the administration’s support for the development of renewable fuels. “Building an active biofuels and biomass industry in every region of the country will help to create jobs and provide economic opportunity for people who live in rural communities,” he said. Payments were made to eligible producers under the Advanced Biofuels Payment Program – Section 9005 of the 2008 Farm Bill – to support and ensure expanding production of advanced biofuels. Vilsack also announced $1.6 million in grant funding for 68 feasibility studies under the Rural Energy for America Program (REAP) – Section 9007 of the 2008 Farm Bill. Grant recipients include: $17,500 feasibility study grant to Select Milk Producers, Inc. in Hale County, Texas to analyze all aspects of a proposed anaerobic digester (AD) project, including conversion of biogas to electricity, compressed natural gas for injection into natural gas pipelines and compressed natural gas for use as a diesel fuel replacement; $40,000 feasibility study grant to the Cayuga County (New York) Public Utility Service Agency to examine a proposal to connect up to 20 Cayuga County farms to a collector pipeline that will deliver farm-produced biogas to produce renewable heat and power for sale to business customers; and $8,250 grant to J & D Wilson and Sons Dairy in Fresno County, California for a feasibility study to evaluate the viability of installing a biomethane recovery and liquefied natural gas plant at the dairy.
Escondido, California
The city of Escondido and Southern California Gas Co. (SoCalGas) began testing a pressure swing adsorption system at the city’s Hale Avenue Resource Recovery Facility (RRF) to upgrade biogas from the treatment plant digesters through a multistage process to pipeline quality natural gas. “The city is always looking for opportunities to take advantage of green technologies,” said Sam Abed, mayor of Escondido. “An added bonus is the fact that the recovery and reuse of this methane gas will save money for our city’s ratepayers.” The $2.7 million demonstration project is expected to continue for up to 12 months in order to prove that this technology can cost-effectively produce renewable natural gas that reliably meets California’s stringent gas quality standards. After that, the equipment will be put into commercial use on-site or, if necessary, moved to an alternative location. The demonstration project is being funded by SoCalGas’ research and development group, and is expected to produce enough natural gas to serve about 1,200 homes.
The project at the Hale Avenue RRF is an example of SoCal Gas’ renewable energy vision. In November, SoCalGas and San Diego Gas &Electric filed a proposal with the California Public Utilities Commission seeking authorization to develop, own, operate and maintain bioenergy production and gas conditioning facilities that would transform organic waste from water treatment plants, farms and other operations into renewable natural gas suitable for power production or injection into utility pipelines. Power generated using biomethane as a fuel qualifies as clean, renewable power. Thus, the increased availability of pipeline-quality biomethane is expected to help electric utilities meet California’s aggressive renewable energy goals.
Washington, D.C.
The U.S. Department of Agriculture published two reports in February dealing with carbon prices, climate change and the adoption of methane digesters on dairy and hog farms to manage potential greenhouse gases (GHG), nutrients and odors while producing electricity and heat for use on and off the farm. According to both the summary and comprehensive reports, climate change mitigation policies that effectively put a price on GHG emissions could allow livestock producers to “sell” these reductions to other GHG emitters who face emissions caps or who voluntarily wish to offset their own emissions. Depending on the direction and scope of future climate change legislation, the reports state, income from carbon-offset sales could make methane digesters profitable for many livestock producers. Of 157 farm-based digesters in the United States (as of October 2010), 126 are on dairies and 24 are at hog operations.
The reports concluded that larger operations would be more likely to adopt a digester and would likely earn substantially higher profits on average than smaller operations. Hence, introduction of a carbon market in a region could enhance existing economies of scale in production and result in further concentration of production on the largest operations. The reports also found that smaller livestock operations may be able to achieve a more efficient digester scale by supplementing manure with food waste products – thus boosting methane production and introducing tip fees – or by sharing a digester with other small operations. The full reports are available at and
Portland, Oregon
Columbia Biogas, LLC. secured key permits in late 2010 for plans to build a food waste digester in Portland. The company is managed by Verde Renewables, which is owned by John McKinney. The proposed anaerobic digestion system is expected to use waste from local restaurants, grocery stores and institutions to produce 5 megawatts of power, with heat to be shared with industrial and commercial neighbors and digested fiber to be sold as a soil amendment. In November, the Oregon Department of Environmental Quality issued air and solid waste permits for the project. Metro, a regional government encompassing Portland and surrounding counties, unanimously approved a franchise permit for the project on December 9. Municipal permits won’t be pulled until the company finishes design details and other business arrangements.
Columbia Biogas will use a two-stage wet digestion process designed by Enbasys. Negatively pressurized loading bays are planned to control odors. Most waste will be processed within a few hours of receipt, undergoing a one- to three-days of hydrolysis followed by three days of fermentation. The facility expects to process about 80,000 gallons/day of liquid waste and 90,000 tons/year of solid waste. Tip fees of $50 to $60/ton are expected. Residential waste will not be accepted. One potential customer is the Port of Portland, whose waste minimization manager Stan Jones spoke in favor of the Columbia Biogas facility at two hearings. The project, Jones said, could avoid the 270 mile round trip currently necessary to send 250 to 300 tons of food waste, plus more from business partners, each year to the Cedar Grove facility in neighboring Washington state. Columbia Biogas is also working with neighborhood stakeholders and community groups to provide services from the facility as well as job training and recruitment and contracts to local businesses. Metro approved Columbia Biogas’ permit with conditions that the company keeps and follows a good neighbor plan and pays a community enhancement fee. Veolia Water North America-West has been subcontracted to operate the facility. Columbia Biogas is discussing the possibility of a 15-year power purchase agreement with PacifiCorp.

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