Green Sanctuary Program
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Bellingham Unitarian Fellowship
Green Sanctuary Program |
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February 18, 2010 Northwest Food and Farms http://nwfarmsandfood.com/index.php/unlikely-renewable-energy-hero The 50,000 cows grazing serenely on Whatcom County’s rich farmland in Northwest Washington supply more than just 133 million gallons of milk every year. They also produce over 1 million tons of manure—waste that could dramatically reduce greenhouse gas and make the Whatcom County and City of Bellingham vehicle fleets energy independent. With the potential to convert manure into biogas which can generate electricity, or (with a little modification) fuel vehicles, innovative farms in Northwest Washington are turning to anaerobic digesters. In 2004, the Andgar Corporation built Washington State’s (and Whatcom County’s) first anaerobic digester at the Vander Haak Dairy near Lynden. The anaerobic digester is a closed vessel where bacteria, in the absence of oxygen, break down manure and other organic material. Vander Haak’s digester is a concrete closed tank 73 feet wide, 150 feet long, and 16 feet high. Vander Haak Dairy gathers the manure from its 750 cows into a collection pit with other organic wastes, such as chicken and fish trimmings, and pumps the waste into the digester. Over the next 22 days, anaerobic bacteria reduce the harmful aerobic bacteria by 99% and generate biogas, as well as a residual solid and a liquid. The biogas is 60% methane (CH4) and 40% carbon dioxide (CO2) with traces of hydrogen sulfide (H2S). Vander Haak burns the biogas directly in a 450-kilowatt diesel generator to produce electricity for the grid. They use the solids as soil amendment and as a pathogen-free bedding for their cows. The liquid, also largely pathogen free, provides fertilizer for fields with nutrients plants can readily absorb without contamination dangers to groundwater. The biogas, however, has an additional and potentially much greater value to the community. In pioneering work, the Vehicle Research Institute at Western Washington University in Bellingham has developed a low cost, small scale refinery technology to remove the carbon dioxide and hydrogen sulfide from the biogas mix. The resulting pure methane can then be compressed into a low emission high-energy vehicle fuel. Running Cars and Buses on Biomass Methane In Whatcom County the potential is huge. Each cow produces approximately 120 lbs. of manure per day, which generates about 60 cubic feet of methane. According Eric Leonhardt, director of the Vehicle Research Institute, 60 cubic feet of methane has the energy content of nearly one-half gallon of gasoline. So Whatcom’s County’s 50,000 cows produce about 25,000 gallons of gasoline equivalent per day. To understand the sustainable energy potential of this amount of fuel, consider that the Whatcom Transit Authority’s fleet of 135 buses and vehicles use about 1,700 gallons of fuel per day. The 25,000 gallons a day of gasoline equivalent from Whatcom County’s cows add up to a formidable 9.125 million gallons in a year—seven times the amount needed to run the vehicles of all of the county’s major government agencies combined. In 2008, the Whatcom Transit Authority, Whatcom County, City of Bellingham, City of Ferndale, and City of Lynden used 1.285 million gallons of fuel. Their entire fuel requirements could be met by only 14% of the combined dairy cows’ yearly methane output. With the remaining 7.84 million gallons of gasoline equivalent, Whatcom County could power 14,000 additional cars (retrofitted to run on natural gas) and reduce its three million tons of CO2 emissions each year by 80,000 tons. In addition, with dairy farms charging a conservative $2.25 per gallon of gasoline equivalent, Whatcom’s farm economy could gain $20 million dollars. Sweden’s Renewable Energy Plan Beyond individual dairies, anaerobic digesters have the potential to create power on a larger scale. Consider the case of Linköping, a city of 98,000 inhabitants, located on the fertile Östergötland plain in southern Sweden. Spurred on by the Swedish Parliament’s mandates to create a sustainable environment, in the late 1990s city and county authorities began to use the region’s dairy manure and meat processing wastes to generate biogas. (See the International Energy Agency report on Linköping.) In the years that followed, Linköping expanded production and distribution of the processed biogas. Today, methane powers the city’s buses and taxis. Most recently, Svensk Biogas, a subsidiary of the city of Linköping, converted a former diesel commuter train methane power for its 50 mile (80 km) run to the coastal city of Västervik. Sweden plans to replace three percent of its imported petroleum with biogas. Methane Energy in Whatcom County Linköping’s use of methane power shows what is possible here. Whatcom County is making a start. Western Washington University’s Vehicle Research Institute recently recieved a $500,000 grant from the U.S. Department of Energy to retrofit three diesel buses to burn methane. Two methane digesters — one in Whatcom and one in nearby Skagit County — are currently in operation, producing electricity for the Puget Power grid. Yet, more can be done. What could a long-term methane digester energy plan do in Whatcom County?
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