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Farming Out Heat and Electricity through Biopower

December 16, 2011 - 4:00pm

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Cows like these in Skagit County, Washington, supply the biodigester developed by Kevin Maas of Farm Power up to 70,000 gallons of manure per day. The newest Farm Power facility in Washington generates enough electricity to power 500 homes. Photo courtesy of <a href="http://creativecommons.org/licenses/by-nc-nd/2.0/">sea_turtle</a>.

Cows like these in Skagit County, Washington, supply the biodigester developed by Kevin Maas of Farm Power up to 70,000 gallons of manure per day. The newest Farm Power facility in Washington generates enough electricity to power 500 homes. Photo courtesy of sea_turtle.

Five years ago, Kevin Maas and his brother Daryl started a business producing electricity from what many would consider an unlikely source -- cow manure.

Kevin Maas developed an anaerobic digester and then a company around a biodigester, which heats and processes dairy manure and other organic wastes in an oxygen-free environment designed to induce digestion by bacteria and then collects the bacteria’s output -- methane-rich biogas.

The system, the first-of-its-kind in the state, stores the gas from the biodigester and then feeds it through bright yellow pipes into an engine generator to produce electricity. After digestion, the fibrous solids are separated and dried, then returned to dairy farms for use as cow bedding. The digested liquid is also returned to farms, stored in lagoons, and then spread on fields, providing nutrients for crop production.

A few years later after learning about the State Energy Program, the Maas brothers applied for and received a $1.06 million Recovery Act grant from the Department of Commerce to construct a second digester near Lynden, a small Washington town just south of the Canadian border.

Nearby MJD Farms, a dairy farm with over 2,000 cows, agreed to supply the manure -- 70,000 gallons per day. 

A closed-loop heat extractor at the Lynden facility uses the heat produced by the burning methane biogas for multiple purposes. First, it heats the digester vessel to sustain bacteria growth. Second, it dries the fiber product. Third, it heats water that is piped to a nearby commercial greenhouse for radiant floor heating.

Maas calculates that the greenhouse, owned by Van Wingerden Greenhouses, will save approximately $30,000 per year in energy costs due to its participation in the digester project. The greenhouse employs 15 workers.

Farm Power Lynden generates over 6,000 megawatt hours of electricity per year, 20 times the amount of power to run its own operations, or enough electricity to power 500 homes. The excess electricity is sold to Puget Sound Energy under a 10-year fixed-price contract.

The methane emissions eliminated by the Lynden facility are projected to reduce net annual greenhouse gas emissions equivalent to taking 3,000 cars off the road.

Farm Power is currently working to establish additional digester projects in the state. “The State Energy Program is outstanding,” said Maas. 

Anaerobic digestion of agricultural waste is a proven and rapidly growing source of renewable energy generated at more than 150 other facilities around the country.

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