ANAEROBIC DIGESTION To help the farmer, CVPS Cow Power has a full-time project manager to help identify funding opportunities, obtain permits, fill out paperwork and work with the digester technology provider. “Dairy farmers (already) have a million other things that they are doing,” Dunn says.
Digester Technology Challenges GHD Inc. of Chilton, Wis., has been the primary anaerobic digester technology provider in Vermont, Dunn says. According to GHD, the smallest dairies served by its
technology have approximately 650 head of cattle. In Wisconsin, Dairyland’s three primary digesters use Microgy-branded technology provided by Environmental Power Corp. of Tarrytown, N.Y.; each of Dairyland’s digesters process manure from approximately 900 cows. However, CVPS and Dairyland digester operations pale in comparison with many of GHD’s and Environmental Power Corp.’s projects, which serve farmers with thousands of cattle. Smaller farmers have been virtually eliminated from cow power programs. To meet this challenge, Kennebeck says
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Dairyland has been working with a company that develops systems for sewage treatment plants and potable water systems to develop a technology that would be feasible for a farmer with as few as 250 head of dairy cattle. He says the smaller reactor is more efficient and costs less. “Working on the development of this smaller tank for smaller herds is something that we’re very interested in doing,” Kennebeck says. “We don’t want to turn our back on the smaller farms.” However, continued research and development is on hold because of the recession. “Nobody has got a lot of walking-around-money anymore,” Kennebeck says. CVPS is in the same situation. “In Vermont, our biggest farm is 1,500 cows and so, compared with the rest of the country, we’re relatively small by comparison on the dairy scale,” Dunn says. He says what is needed are systems that are cost-effective for dairies in the 200- to 300-cow range. To offset the need for more cows, smaller farmers can partner with food companies to process food waste with their manure. Dunn says all CVPS digesters use additional food waste, including whey from cheese-makers, ice cream waste from Ben & Jerry’s, and leftover grease from meat preparation. Kennebeck says he sees Dairyland tapping into sources of whey, turkey manure and vegetable waste for anaerobic digestion. “We have an incredible amount of agricultural waste streams that can be turned into something beneficial that now is not,” Kennebeck says. In the future, operational benefits and regulatory incentives might be enough to get farmers to build anaerobic digesters, even if they can’t install generators to sell power to utilities, Kennebeck says. “Farmers will do this on their own without an electrical component,” he says. “They will do it for bedding, to get the pathogen kill and to generate the gas, which they may be able to use on the farm to heat the home and to heat the barn. “The regulatory world loves these digesters,” Kennebeck says. BIO Ryan C. Christiansen is a Biomass Magazine staff writer. Reach him at rchristiansen@ bbiinternational.com or (701) 373-8042.
28 BIOMASS MAGAZINE 2|2009