On Vermont dairy farm, energy happens

 BRIDPORT, Vt. -- The cows at the Audet family's Blue Spruce Farm make nearly 9,000 gallons of milk a day _ and about 35,000 gallons of manure.

It's long been the milk that pays, in the form of the checks farmers receive from dairy wholesalers who bottle it or turn it to cheese and other products.

But now the Audets _ brothers Eugene, Ernie and Earl and their wives _ have figured out a way to make the manure pay as well. They're using it to generate electricity.

Mixed in with the smelly gasses released by a pile of manure is a main ingredient that is odor-free: methane.

With the help of their power company, Central Vermont Public Service Corp., the Audets have devised a way to extract the methane from the manure and pipe it to a generator.

They make enough electricity to power 300 to 400 average Vermont homes. It's renewable energy _ the cows just keep on giving. And unlike wind power, which depends on the wind blowing, it isn't intermittent. The engine that powers the Audets' generator is shut down occasionally for oil changes, but in 2005, it ran 97 percent of the time, said Dave Dunn, a senior energy consultant with CVPS.

Electricity has created an important new income stream for the Audets' farm at a time when low wholesale milk prices have squeezed their margin. The utility pays 95 percent of the going New England wholesale power price for electricity from the Audets' generator.

In addition, the utility charges customers willing to pay it a 4-cents-per-kilowatt-hour premium for renewable energy and then turns the money over to the Audets. So far, more than 3,000 CVPS customers have signed up to pay the premium to support the renewable energy effort.

The bottom line, given recent wholesale power prices, is more than $120,000 a year from electricity sales. When they add in other energy savings enabled by the project, the Audets expect their $1.2 million investment in project equipment to pay for itself in about seven years.

The program has piqued interest.

Ask Marie Audet her job title and she'll tell you, "Just the wife." Pressed, she'll add, "Bookkeeper, milker." But lately she's also become a tour guide, showing people from the United States and a handful of other countries around the farm's cow power operation.

Managing 1,000 milking Holsteins and half again as many young stock is a high-tech operation. Each animal is fitted with a transponder that communicates with a computer and keeps track of their health, milk production and other data.

Each cow is registered electronically as she enters the milking barn. If the animal's milk production is down, or it is showing other signs of health problems, an automated gate opens and another closes and the animal is directed into the farm's sick bay.

"Happy cows are healthy cows and longer-living cows," says Audet, 46. The cow barns, milking barn and passageways in between have rubber floors. Supporting the animal's massive weight otherwise makes hooves and knees susceptible to injury. "They never walk on concrete, always walk on rubber," Audet says.

In their stalls, cows munch contentedly on a mix of hay and silage while, from their other ends, they make an occasional contribution of fuel for the Audets' power plant. The animals placidly lift one hind leg and then the other as an "alley scraper" _ it looks like a big squeegee on wheels _ comes by to push their manure down the row and through an occasional grate to a conveyor belt below.

From there the manure goes to an anaerobic _ meaning oxygen-free _ digester, a 100-foot-by-70-foot structure similar to a covered swimming pool. The manure spends 20 or 21 days in the digester, being pushed slowly from one end to other as more is added.

Three products result: a liquid that contains enough nutrients that it can be used as fertilizer for the farm's feed crops; a dry, odor-free, fluffy brown substance, some of which is used as bedding for the cows and some of which goes to a local firm that bags and sells it as fertilizer on the home-and-garden market; and methane collected from the top of the digester.

Other farms around the country are using digesters to make energy, said Corey Brickl, project manager with Wisconsin-based GHD Inc., which built the Audets' digester. Some are loading their digesters with other waste aside from manure, Brickl said, describing one in Washington that uses tomato waste from a salsa factory and waste from a fish stick plant as fuel. "A digester will work with carbon-based material," he said.

A key advantage for the Audets, something that makes their situation rare if not unique, is the extra 4 cents per kilowatt-hour they get under the CVPS green energy program, which it has dubbed Cow Power, said CVPS spokesman Steve Costello.

"A lot of utilities have thrown up roadblocks" for farmers who want to sell power onto the grid, Costello said, while CVPS has taken the opposite approach.

Some farms are finding anaerobic digesters a worthwhile investment even without making power from the methane, Brickl said. "They're just flaring it" _ burning it off. Doing so produces carbon dioxide but that's a far less potent greenhouse gas than the methane that otherwise would be released. "They're doing it for herd health, bedding for cows," and as a way to manage manure better, he added.

Audet said the farm was saving the $1,200 a week it formerly spent on sawdust bedding for the cows, as well as some of the cost of heating the milking barn. Agricultural scientists from the University of Vermont did a study for a while with half the Audets' herd on traditional bedding and half on the new output from the digester. Sawdust lost. "Wood harbors a lot of bacteria," she said.

The methane is piped into an adjacent shed that contains a big Caterpillar engine that powers the 200-kilowatt generator. The engine also gives off heat that is used to keep the digester warmed to 101 degrees _ the temperature of a cow's stomach.

Outside the generator building, Dave Dunn, a senior energy consultant with the power company who worked with the Audets on the cow power project, points up at a series of three transformers on utility poles that boost the 480 volts put out by the generator to the 1,270 volts that CVPS carries on its transmission system.

Dunn said the Audets "really deserve to be congratulated. They're the pioneers among Vermont farmers" in delving into a new form of renewable energy. Four other Vermont farms now have similar projects in the planning or early construction stages, CVPS officials said.

The $1.2 million the Audets invested went for the digester, generator and related equipment. They bought the 20-year-old Caterpillar engine used. "Saving money _ you know, we're dairy farmers," Marie Audet said.

Audet said a main motivation for the farm family's involvement in the project was better manure management. New state and federal rules are aimed at cracking down on phosphorus-laden farm runoff getting into streams and Lake Champlain.

"Our reason was to manage in a responsible way the waste we generate," she said. The new system creates a "very closed loop" of manure management, Audet added.

How's the project worked out so far? Well enough that the Audets are expanding it by adding a new, 75-kilowatt hour generator to the 200-kW unit already in place.

Audet said she's even grown to like giving the tours. "It's bringing a lot of people to the farm who are normally very removed from food producers."