BRISTOL — The Vermont Public Service Board has given the green light to a major methane-to-electricity facility at one of the county’s largest dairy farms.
It was this past Jan. 6 that Four Hills Farm requested a certificate of public good from the Public Service Board to install and operate a 525kW methane electrical generating facility at its 722 Burpee Road headquarters in Bristol. Four Hills has 2,500 head of cattle, around 1,250 of which are currently being milked.
Functioning as part of Central Vermont Public Service Corp.’s “Cow Power” program, the farm will soon be able to repurpose its manure into an estimated 3 million kilowatt hours of electricity per year, according to David Dunne, manager of renewable projects for CVPS. That 3 million kWh would supply roughly 18 percent of the combined energy needs of Bristol, Monkton, New Haven, Starksboro, Ripton, Lincoln, Huntington and Buel’s Gore, which are all served at one central substation, Dunne noted.
The new venture represents around a $2.5 million investment for Four Hills, a payout the farm owners will be able to gradually recoup through a couple of sources, according to Dunne.
First, the project will be enrolled in the state’s Sustainably Priced Energy Enterprise Development program (known as SPEED), through which qualifying renewable energy enterprises are paid a premium of 14 cents per kWh of electricity generated. CVPS customers are given the option of paying that premium rate for their Cow Power electricity.
“It will be a piece of their farm revenue,” Dunne said. “It should become a self-sustaining piece of their business.”
Second, the farm will capture, as byproducts of the methane-to-energy process, a higher-quality manure fertilizer and an abundant source of cow bedding.
“Even if it just cut our bedding costs in half, we would be happy,” said Shannon Hill, spouse of one of the farm’s partners, Brian Hill. Four Hills is a partnership consisting of Brian, Ronald, Joanne and Kevin Hill.
The Hills, in their application to the Public Service Board, described a project that will include construction of three buildings: an enclosed, in-ground, concrete, anaerobic manure digester measuring 200 feet long by 72 feet wide by 16 feet deep; a solids storage building measuring 120 feet long by 60 feet wide by 42 feet high; and a building housing the generator and solids-separator equipment measuring 96 feet long by 40 feet wide by 22 feet high.
The project, according to the application, is designed to be similar in appearance to the existing barns and outbuildings at the farm and will be built adjacent to existing farm structures.
Plans calls for the digester to process manure produced by cows at the farm and by off-farm feedstocks. The material will be pumped from the stall barn into an existing storage tank and then into the digester, where it will be mixed and heated. The naturally resulting decomposition will produce methane gas and biosolids.
The methane will be collected and used to fuel a “reciprocating engine” that runs a generator and in turn produces energy. The biosolids will be pumped from the effluent pit at the end of the digester to a mechanical separator. The liquid and solids, with many of the pathogens and odor characteristics greatly reduced through the digestion process, will be separated out. The solids will be treated and mainly used as cow bedding, at a savings over the cost of sawdust. The liquid waste (containing less phosphorous) will flow by gravity into an existing earthen lagoon and then will be used as fertilizer.
Electricity generated by the system will be patched into the power grid and distributed by CVPS.
“We hope to have (the system) running by June 1,” Shannon Hill said.
Four Hills will become the 11th farm statewide to participate in CVPS’s Cow Power program. Participating Addison County farms include Blue Spruce in Bridport, Dubois in Addison and Monument Farms in Weybridge. The current 10 farms produced a combined total of 1.3 million kWh of electricity in March, Dunne said. The average residential user consumes around 500 kWh per month. That means they produced enough electricity for 2,600 average homes.
Since being established in 2004, Cow Power customers have contributed around $3 million in 4-cent premiums toward the renewable energy program, according to Dunne. Around 3 percent of CVPS’s 160,000 customers are participating in the Cow Power program, he said.
There are also around 200 commercial customers of Cow Power, including Middlebury’s Cooperative Insurance Co., Vermont Hard Cider and some Middlebury College accounts, Dunne said.
“We are looking for more (Cow Power) customers,” he said.
Reporter John Flowers is at [email protected]