June 16, 2011 | General

Anaerobic Digest

BioCycle June 2011, Vol. 52, No. 6, p. 15

Gooding, Idaho
A large anaerobic digestion system in rural Idaho is converting manure from about 4,700 dairy cows to 1.2 megawatts of electricity, sold to Idaho Power. Big Sky West Dairy in Gooding utilizes modified mixed/plug flow GHD digester technology. Manure is scraped into a flume, flushed into a collection pit and then pumped to the digester.
The biogas fuels two 710 kW cogeneration units. A two-stage solid-liquid separation system is used, and manure fibers are separated out and used to provide bedding for the livestock. The remaining fiber and emissions credits are sold to third parties.
The system was featured in an onsite tour during the recent AgSTAR national conference. In operation for two-and-a-half years, the project is producing power at 105 percent of original projections. It is a joint venture of Dean Foods and Ag Power Partners and is operated by Andgar Corporation. “We had anticipated that it would work very, very well,” said Bob Joplin of Ag Power Partners. “It’s better than we projected. This year so far, we’re at 95 percent uptime.” He said a similar system would work well at dairies where cows are kept in free stalls and the water use is such that the solid/liquid ratio can be kept at optimum levels.
Oshkosh, Wisconsin
An 8,000 tons/year dry fermentation anaerobic digestion system is undergoing commissioning (primarily equipment testing) following a dedication ceremony in mid-May. Actual loading of the units with food waste and yard trimmings is anticipated in late July. The facility, located on the campus of the University of Wisconsin-Oshkosh, was designed and constructed by BIOFerm Energy Systems. The university owns the facility, which is projected to provide the campus with 8 percent of its electricity needs. A combined heat and power unit supplied by 2G Cenergy (370 kW cogeneration unit) will generate about 2.3 million kWh annually. The 7,900 MMbtu of thermal energy will be used to heat adjacent buildings. The project was funded in part by grants from Wisconsin Focus on Energy and the federal government.
After 28 days in the fermenters, material will be transported to a commercial composting site. Feedstocks for the digester will come from campus dining halls and landscaping trimmings, as well as from the city of Oshkosh.
Rutland, Massachusetts
With more than 200 people and 350 cows in attendance, Gov. Deval L. Patrick celebrated the opening of Massachusetts’s first commercial anaerobic digester at the 375-head Jordan Dairy Farm, proclaiming that “We are at a moment in history, and you have invented the pathway here. I feel very strongly about inventing our future and applying ourselves to make it a reality.” Following nearly four years in planning and development, the Jordan Farm digester is the first of five on-farm digesters being developed by the Agreen Energy Project, the farmer-owned company that partnered with Casella Waste Systems to supply the food waste and operate the digesters. At the ribbon cutting, refreshments were provided by HP Hood, Cains Foods, Cabot Creamery and Kayem – companies that will be sending source separated organics (SSO) to the five farm digesters and will purchase power from the projects.
The $3 million Jordan Farm project utilizes a German-designed mesophilic complete-mix digester from Quasar Energy Group that will process liquid dairy manure and food waste. Quasar reports that all components for the Jordan Farm project were manufactured in the U.S, and it is anticipated that each farm will generate 450 kW. Although the project took four years to permit and develop, it is anticipated that the next four digesters will all be developed within the next two years, thanks to the regulatory pathway Gov. Patrick referred to that evolved through the Jordan Farm project (see “Permitting Farm Codigestion,” September 2010). The Massachusetts Department of Environmental Protection, in support of its Solid Waste Master Plan objectives to divert SSO from landfills and incinerators, applied a policy that exempts conventional material recycling facilities from solid waste permitting to conversion of SSO at the five on-farm digesters. The same logic of beneficially using recycled materials is applied to the farm projects in consideration of the fact that energy and fertilizer are being manufactured from the manure and SSO.
Financing for the Agreen Energy projects comes from Farm Credit East, backed by a loan guarantee from USDA Rural Development and subsidized with grants from USDA NRCS, Mass Clean Energy Collaborative, Massachusetts Department of Agriculture and Federal stimulus funds. The Massachusetts Green Communities Act also qualified the electricity from the projects to receive $0.14 per kWh, in addition to resulting Renewable Energy Credits. Future projects will likely include adjacent greenhouses to utilize excess heat and produce revenue from sale of produce grown in the greenhouses.
Boise, Idaho
An ambitious goal of seeing 1,300 anaerobic digesters operating across the country by 2020 was recently announced jointly by a The Innovation Center for U.S. Dairy (Innovation Center), the Dairy Research Institute and Idaho’s Center for Advanced Energy Studies. Currently, about 160 on-farm digesters operate in the U.S. (Germany has more than 5,000). Chris Voell, program manager of the U.S. Environmental Protection Agency’s AgSTAR program, said in a BioCycle interview in April (see “On-farm Anaerobic Digester Trends In The United States”) that there needs to be “a fundamental shift” in business models, energy policy and public support for anaerobic digesters to take off in this country.
The “fundamental shift” that Jerry Bingold, director of renewable energy for the Innovation Center, sees is bringing in a third-party entity to finance and run the anaerobic system, taking the financial investment and risk off the farmer’s back. He explains that the current financing methods for other renewables, such as wind and solar, are backed by the equity of the systems. Farmers typically need to invest around $1 million for an anaerobic system and the entire farming operation can be at risk if the project fails. With a third party – specialized in building, owning and operating digesters – the farmer can lease out a few acres of land and receive free bedding and fertilizer while saving money on manure management, Bingold says. “There’s some strong benefits to the dairy.” Under this model, the operating partner would take biogas from the operation to sell for power generation or as natural gas if a pipeline is close by. At one site, he notes, developers are planning to make compressed natural gas to run farm vehicles and milk trucks.
Currently, 2,600 U.S. farms have been identified as potential sites for such operations, Bingold adds. One project moving forward is a $24 million digester system in Idaho that will collect manure from 15,000 cows and generate 4.5 megawatts of power – the largest dairy biogas project in North America. The project is a build-own-operate model with no risk to the farmer and no requirement for a personal loan guarantee. It is wholly owned by Camco International Unlimited and operated by the consortium AgPower Group LLC.
Bingold says investment tax credits offered through the American Reinvestment and Recovery Act are still available for digester projects that are 5 percent complete by the end of 2011, adding that several projects are likely to receive funding. What is needed to qualify, he explains, is a supply agreement in place for 20 years, a technology guarantee that the digester will work no matter what, and products from the venture – power, biogas, fiber, carbon and fertilizers – that can assure there’s more revenue than debt at a 1.5 debt service coverage ratio. Projects that qualify receive a 30 percent tax grant for construction costs after six months of operation. “One other thing that’s driving this industry now is the immense amount of business that is being generated from food waste,” Bingold adds.
Zebulon, North Carolina
Barham Farms in Zebulon, began construction of a digester to process 90 to 140 tons/day of food waste from area grocery stores, including a Walmart, with manure from about 4,000 hogs. Construction began in May and the digester is scheduled to start up in October or November. The food will be blended with crop waste from the greenhouses, ground and directed to a 750,000-gallon complete mix high temperature anaerobic digester designed and supplied by Brinson Farms LLC in Prentiss, Mississippi. Effluent in the system will flow into a lagoon and be pumped to the greenhouses, where it is applied to tomato plants. A composting system is also in place at the site. Barham Farms previously generated energy with a digester, but shut down the generator project in 2003 after failing to secure a contract with a local utility. Biogas from the Brinson digester will be used to produce energy for the greenhouse operation.
Eagle Green Energy, Inc., the operational arm of Brinson Farms, includes composting operations in all the projects it builds, according to John Logan, president and manager of Brinson Farms and CEO of Eagle Green Energy, Inc. He said an agreement with Walmart to provide food waste has been essential to digesting and composting projects it is involved with in Mississippi.
Boston, Massachusetts
The State of Massachusetts’ Agriculture Energy Grant (AEG) program has been targeting clean alternative energy technologies, with grants of up to $30,000 being awarded. Proposals for the current round of funding (FY2012) are due June 30. The AEG program has funded 59 projects totaling about $850,000 to date. Grants in this year’s cycle will be available for: biofuel crops grown on marginal soils or in crop rotation, biofuel production, high-efficiency advanced gasification biomass thermal boilers or furnaces and advanced biomass wood boilers (outdoor wood boilers or OWB). Gerald Palano, alternative energy specialist for the state’s Department of Agricultural Resources, says anaerobic digesters are funded through this grant program. He notes the department helps with engineering design and provides technical support for understanding the feedstock mix, potential fuel content and methane generation.
The Request for Proposals for energy efficiency grants focuses on dairies, greenhouses and nurseries. Grants also can target renewable technology projects that advance urban food gardens. Palano said a surge in support for seasonal food production and buying local, as well as this year’s USDA elimination of the geographic eligibility requirement for the Rural Energy for America Program, have opened up opportunities for urban gardeners. “We’ve seen some great proposals to use food waste and landscape waste for compost or for biomass fuels,” he says.
Burning of biomass has been a contentious issue in Massachusetts. Under the grant guidelines, all biomass projects must meet current federal, state and/or local construction, emission and efficiency standards. OWB systems must meet local board of health requirements and be installed and certified under the Massachusetts Department of Environmental Protection requirements.

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