Cow Power: photo by Art Oglesby, Cow manure can produce electricity.

What comes out of the back end of a cow?

Milk and manure. The cows at the Audet family's Blue Spruce Farm make almost 9,000 gallons of milk a day — and about 35,000 gallons of manure. With the help of their power company, Central Vermont Public Service Corp., the Audets have devised a way to extract methane from the manure and pipe it to a generator. They make enough electricity to power 300 to 400 average Vermont homes.

How can electricity be made from cow manure?

If cow manure is pushed into a long, narrow tank and held around 100 degrees, in about 20 days bacteria will digest the manure into methane gas and a liquid slurry. The methane can run an engine and generator to make electricity. A dry, odor-free, fluffy brown substance that is used as bedding for the cows can also be extracted. The remaining liquid contains enough nutrients that it can be used as fertilizer for the farm's feed crops.

Do farms in Minnesota make electricity from manure?

Since late 1999, the Haubenschild farm has been converting their cow manure into electricity. At first they, too, digested manure producing methane which fueled a generator to produce electricity. Then, on Jan. 27, 2005, for the first time anywhere in the world, the methane was fed into a fuel cell.
A fuel cell is like a battery. A chemical reaction generates the electricity. It is totally quiet, and the only waste product is clean water. Haubenschild said it costs 5.1 cents per kilowatt hour to produce electricity from the fuel cell and Great River Energy will buy the surplus electricity from the fuel cell for four cents per KWH. If Minnesota power companies can create a progam similar to Vermont's Cow power program, customers willing to pay a couple extra cents per KWH would allow farmers to make money instead of losing money.

What are the benefits of anaerobic digestion?

Reduced odor and greenhouse gas emissions
Fewer pathogens in the digested product
Nutrient rich effluent to apply to crops
Electricity to use and to sell
Possible sale of separated solids as a garden amendment
Good manure management
Pay back on the investment

Read more about Cow power
Biosystems and Agricultural Engineering Department, Univ. of MN.
Princeton Union-Eagle
Pioneer Press
FAQ about CVPS Cow Power

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