That doesn't mean that dairy farming can't be sustainable -- or a least approach sustainability. This much we can be sure of: as long as cows exist there will be manure. Keeping that manure out of our streams and lakes, and turning it into energy puts us on a sustainable path. (GW)
Electricity From What Cows Leave Behind
By Katie Zezima
September 24, 2008
For years, the cows at Green Mountain Dairy here produced only milk and manure. But recently they have generated something else: electricity.
The farm is part of a growing alternative energy program that converts the methane gas from cow manure into electricity that is sold to the power utility’s grid.
Central Vermont Public Service, which supplies electricity to 158,000 customers around the state, was among the first utilities in the country to draw electricity from cow manure on dairy farms. About 4,000 utility customers participate by agreeing to pay a premium for the electricity.
“We realized we could help meet a customer demand for renewables, help solve a manure management problem and make these farmers more financially secure,” said Steve Costello, a spokesman for Central Vermont Public Service.
Residents and businesses that get their electricity from the program pay a premium of 4 cents a kilowatt hour above the typical rate of 12.5 cents. Most of that money goes to the farmers, who must purchase their own equipment, which can run up to $2 million per farm. Most farmers expect to make back their investment in 7 to 10 years.
The brothers who own Green Mountain Dairy, Bill and Brian Rowell, were looking to squeeze more profit from their farm, where they have 1,050 cows and have begun acquiring 600 heifers. Milk prices had dipped and they wanted another source of income.
They also thought that the huge amount of waste their cows produced could be used for something other than fertilizer. So they decided to give electricity a try, armed with about $750,000 in federal, state and utility company grants.
“We saw this as an economic and environmental management tool,” Bill Rowell said. “It’s helped to diversify our farm,” which was named the 2008 Vermont Dairy Farm of the Year.
The Rowells’ cows live in a barn where a mechanical scraper sweeps the animals’ waste into a large drain. The waste is then pumped into a huge sealed concrete tank known as a digester, which holds 21 days’ worth of waste and is kept at a temperature of 101 degrees Fahrenheit. Anaerobic bacteria break down the organic matter in the waste, producing a mix of methane and other gases, known as bio-gas. The gas is burned in an engine that runs an electrical generator.
The cow waste produces 250 to 300 kilowatts of electricity daily, enough to power 300 to 350 homes, according to the utility.
“We’re making a resource out of a waste stream,” said Bill Rowell, who is running for the State Senate.
In return, the Rowells receive a payment based on the wholesale cost of power, which averages about 7 cents per kilowatt hour, plus the 4-cent premium. Mr. Rowell said they earned about $200,000 from electricity annually, and with the additional cows should receive $235,000 to $240,000 in revenue from electricity.
The Rowells are also transforming commercial waste. The farm processes about 500,000 gallons of waste and outdated ice cream from Ben & Jerry’s each year and puts it in the digester. The free ice cream, which the company drops off, helps the Rowells generate more electricity and saves Ben & Jerry’s the cost of disposing of it. “We’re improving our processes, and they’re improving theirs,” Mr. Rowell said.
The digester produces more than electricity. After 21 days, the waste is pumped through a separator, which siphons off the liquid into a silo and drops the solids into a barn.
The liquid manure is used as fertilizer, while the solids are used for cow bedding. The bedding saves the Rowells thousands of dollars a month on sawdust, and they sell the excess to garden stores.
Other utilities across the country are purchasing power from farms as part of their renewable energy portfolios. Some, like Central Vermont Public Service, charge their customers a premium, while others do not.
Alliant Energy, which supplies electricity to rural customers in
“Our economy is agriculture, and people recognize that supporting the industry is a positive,” Mr. Johnson said. The utility charges 2 cents a kilowatt hour more for cow power.
“Rural customers, in particular, are very excited that something that is considered by some to be a liability, manure, has become, in essence, a resource,” Mr. Johnson said.
“We were interested in finding a type of green power that was, No. 1, not intermittent, like wind or solar,” said Steve Oden, a spokesman for Buckeye, which will not charge extra for the power.
Marie Audet’s family farm in
“We’re saving money by not using sawdust, reducing original waste by recycling and generating revenue by selling electricity into the grid,” Ms. Audet said.
And many customers here have chosen to pay more for power that is both renewable and supports local farmers.
Maggie Hatch, who owns the Newbury Village Store in
“It’s worth it to us to spend that money to help the producers and use power that helps sustain the environment,” Ms. Hatch said. “When you live in a place like we do, which is a beautiful part of the country, you’re really aware of the environment and want to keep it that way.”