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Vermont Cow Power Program Makes Most Out of Manure, Benefits Farmers and Environment

April 12, 2012 |

Some might underestimate the power behind a cow—or let’s just say the power that comes from a cow’s behind.

But that’s not the case with electric utility Central Vermont Public Service (CVPS), which uses its Cow Power program to make the most out of cow manure while simultaneously lowering the manure’s negative impacts on the environment and benefiting farmers’ bottom lines.

By partnering with the Cow Power program, 10 dairy farms in Vermont have been able to acquire anaerobic digesters for their farms. The digesters are used to turn cow manure into renewable energy, which is sold back to the utility and then purchased by local customers who are willing to pay a little bit extra for the cleaner power. The process also leads to the production of things like bedding material and compost, which can be sold by the farms or used directly on their own operations.

The CVPS program was initiated in 2004, though it’s first Cow Power farm wasn’t producing digester-generated renewable energy until 2005. Since then, the program has grown dramatically. Cow Power added its 10th farm in November and it’s currently in the process of adding two more this summer, said Dave Dunn, manager of renewable projects for CVPS. Dunn said even more growth lies ahead on Cow Power’s horizon.

“I expect by the end of 2013 for us to have a total of 18 digesters in Vermont,” he said.

Cow Power uses a state feed-in tariff (which pays a predetermined price for the energy) and a voluntary additional charge to customers of 4 cents per kilowatt-hour to reimburse its partners for their power. The program also takes advantage of local, state and federal grants that help farmers pay for their digesters, which can be pricey and are often out of the reach of farmers’ budgets.

Dunn and partner farms note that the following benefits result from the Cow Power program: it provides a stable revenue stream for the farms; it provides farms with considerable savings due to resulting byproducts from the anaerobic digestion process such as bedding material for the cows; and it also provides a way to reduce methane gas emissions and odor levels.

“There’s a methane reduction for farms (that) store manure and use it periodically as a fertilizer,” said Dunn, who noted that methane has a global warming impact that is 22 to 24 greater than carbon dioxide. “We’ve seen on our first 10 farms a significant climate change impact.”

Launching Cow Power

“I knew of digester technology, most of which had failed during the 1970s during our last energy crisis,” he said. “I wanted to see if we could re-stimulate or rejuvenate that market. I had a lot of farms in Vermont that I thought would be able to benefit from the technology.”

He noted that the state Legislature had passed a bill during that time (the early 2000s) that allowed utilities to create a voluntary option for customers to support renewable energy. But nobody had really figured out a way to fully utilize that option, he said. That’s when Dunn and others at CVPS started considering implementing a voluntary tariff program of their own.

With the support of customers willing to pay an extra 4 cents per kilowatt hour for their cow-powered electricity with the knowledge that it would benefit farmers or support renewable energy market, the voluntary tariff became available in 2004.

Starting in 2004, the farmers were able to cover the basic costs of the energy with the tariff, plus they were able to receive an additional incentive of 4 cents per kilowatt hour paid by customers in the program. (Customers can choose to buy 25 percent, 50 percent, or all of their energy through Cow Power.)

CVPS also set up a renewable development fund, which would help pay for project grants and a project coordinator. Meanwhile, CVPS had also recruited its first partner.

Audet’s Blue Spruce Farm, a family-owned dairy farm in Bridgeport, Vt., was Cow Power’s program pioneer. It started producing renewable energy in January 2005, Dunn said.

“I knew (Blue Spruce Farm) to be an innovative and focused-on-environmental-issues type farm,” Dunn said. “We worked together to get their project started, to actually build a digester with the assumption that in 2004, when we offered the tariff,  that people in Vermont would pay for that premium.”

Marie Audet, a member of the part of the family that runs Blue Spruce Farm, said the move was considered a business decision and a way to generate additional cash flow.

“We were all starting at that time to understand that there was some value to capture that methane from the cow manure,” she said. “We’re avoiding all those gases from going into the atmosphere, and additionally we are providing our neighbors with a renewable energy source, so it goes way beyond the economics.”

That first digester cost about $1.3 million, and about 13 percent of that cost was paid through grant funds, Audet said. The farm also recently added a second digester, which cost about $1.8 million.

Here’s how Blue Spruce Farm’s Cow Power operation works:

A scraper that “looks like squeegee on wheels” moves slowly and constantly across rubber-coated barn floors, collecting the cow manure, according to the farm’s website. The manure is then pumped into the biodigester, which looks like “a concrete in-ground swimming pool with a concrete cover.” Excess heat from the generator is used to keep the digester at the same temperature as a cow. Methane gases collects at the top of the digester and are used to power generators, which “push enough electricity onto the grid for about 300+ homes.”

And if that’s not enough of a value, a mechanical separator creates two byproducts—liquid, which is used as fertilizer for the farm’s crops (applied through an aerator); and undigested plant fibers, which are turned into bedding material and fertilizer compost, used on the farm itself and sold to others. (For many Cow Power farms, this bedding is used as an alternative to imported sawdust bedding.)

Furthermore, excess heat and used oil from the process are directed toward operations on the farm.

Diagram illustrating how Cow Power works. Courtesy of CVPS.

Challenges to bringing other farms online

However, even with the success of this first project, it took some time to get other farms started in the program, Dunn said.

“Even though the technology had existed for years, it had not really gained widespread acceptance,” Dunn said. “The reason for that is building the systems is expensive, and they’re also expensive to own and operate and maintain. So, we looked at how we could get over that hurdle.”

CVPS’ grant fund and other government grants have made it possible for farms to subsidize some of that cost. This grant assistance has varies widely, Dunn said. From 2005 through part of 2010, it generally made up about 40 percent of the project cost, Dunn said. Then starting in 2010, that has even gone as high as 70 percent with the help of the Renewable Energy Production Tax Credit, which was made available to projects through the U.S. Treasury as a 30-percent grant on project completion.


By December 2006, Cow Power’s second farm, Berkshire Cow Power LLC in Richford, became active in the program, Dunn said. Green Mountain Dairy Farm in Sheldon was the third farm, which started with Cow Power in March 2007. Seven other farms followed step.

The program currently has about 3,500 customers, compared to the 2,000 customers it had at the end of 2005, its first full year of operation, Dunn said. The farms in the program have so far produced almost 53 million kilowatt hours of renewable energy through the program, compared to the $1.2 million kilowatt hours Blue Spruce Farm produced by the end of 2005. Since Cow Power’s inception, customers have paid more than $3 million in 4-cent premiums, Dunn said.

Meanwhile, the story of Cow Power and some of its farms has spread far and wide. Blue Spruce Farm is going to be featured as a Cow Power farm on PBS’s “America Revealed” series this month. It has also been featured on the Discovery Channel and other major media outlets. Green Mountain Dairy Farm has received nearly 16,000 visitors over the last five years from 23 different countries.

“They’ve heard there’s a Green Revolution going on in Vermont and that farm methane is a recognizable part of that,” said Bill Rowell, who operates Green Mountain Dairy Farm with his brother, Brian Rowell. “They want to see how we’re doing this.”


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