March 23, 2011 | General

Anaerobic Digest

BioCycle March 2011, Vol. 52, No. 3, p. 22

San Rafael, California
The Central Marin Sanitation District (CMSA) is moving forward with an innovative Food to Energy (F2E) project to divert commercial food waste from the landfill and process it in two existing digesters at CMSA’s wastewater treatment plant (WWTP). Final design plans were recently approved by the CMSA board. The project is now out for bid with an award expected by mid-April. The new facility is a component of a larger capital project where improvements are being made to the CMSA’s wastewater treatment plant digesters and mixing system. As part of the plan, the local solid waste hauler, Marin Sanitary Service (MSS), will collect, sort and preprocess the food waste at its transfer station, then deliver the material to the new renewable energy facility at the WWTP. The facility will be ready to receive commercial food waste about a year after construction begins.
“We conducted a methane capture study with the city of San Rafael and Marin Sanitation Service to determine whether it was feasible for MSS to collect commercial food waste from its service area and bring it to their transfer station to do the processing,” says CMSA’s General Manager Jason Dow. Next, a predesign report mapped out three scenarios that evaluated where to build the new facility, type of equipment to be used and how the new operation would interface with existing infrastructure. The chosen alternative couples another project to process fats oils and grease (FOG) with the one to process food waste. Once the food is cleaned and ground up, it will be comingled with the FOG and injected into the digesters.
“Our wastewater treatment plant’s two digesters have quite a bit of unused capacity,” explains Dow. “We can process over 100 tons/day [combined FOG/food waste].” Biogas from the digesters has been powering a 750 kW Waukesha engine but only enough was being produced to power the genset eight hours/day. In the late 1990s, the system was hooked up to a local utility’s natural gas pipeline so it could be switched over when the biogas ran out. With efficiencies maximized, Dow says the engine now runs about 12 hours a day on biogas and the remaining 12 hours on natural gas. “If Marin Sanitation collects all the available food waste in its service area, we believe we can run almost fulltime on biogas, which would make us energy self-sufficient,” he adds.
Williamsburg County, South Carolina
The Burrows Hall hog farm in Williamsburg County joined forces with Santee Cooper, South Carolina’s state-owned electric and water utility, and Environmental Fabrics, Inc. (EFI), a digester construction company, to install a digester to treat swine manure. The 180-kw Burrows Hall Renewable Energy Facility is expected to begin generating renewable energy for the grid early this summer. Duffy Connolly, owner of Burrows Hall Farm, approached Santee Cooper four years ago with the idea of building an anaerobic digester to generate electricity. The South Carolina Energy Office granted $199,995 for the initial feasibility study by Clemson’s South Carolina Institute for Energy Studies using funds from the state’s Department of Agriculture. EFI, which is building an earthen, insulated covered lagoon that is heated and mixed is paying the construction costs and will own and operate the digester. Santee Cooper has contracted to purchase the power from EFI, which Santee Electric Cooperative will distribute from Burrows Hall to the Santee Cooper transmission network. Generating equipment includes a 200 kW MAN and a 180 kW Marathon generator. Santee Cooper has 197 MW of renewable generation already online or under contract to come online in the next couple of years, including power generated from landfill biogas, forest-waste biomass, solar and wind. “Now we can add agricultural biogas to the lineup,” says Marc Tye of Santee Cooper.
Oxnard, California
Agromin, a large organics recovery and composting company based in Oxnard, California, and Zero Waste Energy, LLC, a waste processing solutions provider and project developer in San Jose, have begun the permitting process for their first biogenic energy facility (biogenic is defined as “produced by living organisms or biological processes”). The two companies plan to transform a 9.6-acre green waste composting site in Santa Paula, California, into a 26-acre Biogenic Energy Park that will include anaerobic digestion and biomass gasification facilities. “These will have the capability of generating up to 1.7 megawatt (MW) of biogenic renewable energy per year from 52,000 tons of green waste and food waste at the anaerobic digestion facility and 15,000 tons/year of clean wood waste at the biomass gasification facility,” says Bill Camarillo, CEO of Agromin. “We will also be adding state-of-the-art [covered aerated static pile] technology to the current compost operation.”
Agromin owns and operates the 9.6-acre compost facility, which manages green material for the surrounding cities of Ventura, Santa Paula, Fillmore, Carpinteria and the county of Ventura. It is located on property owned by Limoneira Company, a producer of lemons, avocados, oranges and other specialty crops. Agromin will supply the organic materials for the project, including green, wood, agricultural and food wastes, says Camarillo. Zero Waste Energy will convert these organics into biogas using the Kompoferm Plus dry anaerobic digestion technology developed by its German partner Eggersmann Anlagenbau. The digester will be sized to process 26,000 tons/year of commercial food waste and green waste.
The biogas will be used to generate electricity and transportation fuel. Limoneria Company will use the electricity for cooling and operations in its 200,000-square-foot packinghouse facility in Santa Paula, which processes 3 million field cartons of lemons annually. Fuel produced from the biogas will be sold to a Ventura-based trash and recycling hauler, E.J. Harrison & Sons Industries. The project will be developed in three phases but permitted as one project. Phase 1 includes the digester and construction of a covered aerated static pile (CASP) facility to compost 100,000 tons/year of green waste and cocollected food waste. The 1 MW biomass gasification facility will be constructed in Phase 2, followed by the planned addition of a second anaerobic digester to process another 26,000 tons annually of commercial food waste and green waste in Phase 3.
“The proposed facility will increase landfill diversion in Ventura County from the current 80,000 tons/year to 152,000 tons/year, helping to achieve an 80 percent recycling rate and comply with upcoming measures in the AB 32 Scoping Plan to reduce greenhouse gases by 29 percent by 2020.” The facility is scheduled to begin operating in spring 2012.
Montpelier, Vermont
In order to avoid the appearance of competition between two agencies, USDA Rural Development and Natural Resources Conservation Service (NRCS) developed a working partnership to deliver services to producers interested in making on-farm anaerobic digester part of their farm operations. Much collaborating has taken place since, e.g., in one case, costs of the digester components were split between the agencies into “manure handling” and “electrical.” NRCS provided Environmental Quality Incentive Program (EQIP) financial assistance for the former, including the digester, manure pumps and separator. Rural Development provided a grant and low interest loans for the electrical generation equipment including engines, generators and electrical hook up. Costs broke down into a roughly 50 percent split in terms of what each program is authorized to cover with assistance.
If an eligible producer has no other contracts with NRCS, up to $450,000 in financial assistance can be available to at least partially fund 50 percent of the project costs. Coordination between NRCS and Rural Development also enables the agencies to provide assistance without the risk of duplicate funding.

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