What goes around comes around, you might say, at Blue Spruce Farm in Bridport.
With the only operating manure digester in the Northeast, the giant dairy farm is able to convert moo doo from 1000 milkers and hundreds of heifers into enough renewable energy to light 800 average-size Vermont homes. It's the methane from all that manure that powers an electricity generator at Blue Spruce linked to the lines of the local utility, Central Vermont Public Service Corp. If the methane weren't captured in the concrete-encased digester, it would be released into the atmosphere and act as a global-warming gas 20 times more potent than carbon dioxide.
Excess heat from the roaring generator, which produces at least as many decibels as degrees, meanwhile gets pumped into the hot-water pipes in Blue Spruce's milking parlor and office, saving $10,000 in annual heating costs.
The generator keeps the manure in the 14-foot-deep digester at the same temperature as that of a cow's stomachs - 101 degrees Fahrenheit. After 20 days of enhanced anaerobic activity, a mechanical separator processes a portion of the manure into a sand-colored, crumbly material that's used as bedding for the Holsteins, which never leave the barns. By eliminating the need for sawdust, this decontaminated solid saves the farm another $55,000 a year.
The manure that remains in liquid form will eventually be spread over most of Blue Spruce's 2000 acres. This fertilizer for the farm's feed crops doesn't have the sickening stench of unprocessed liquid manure. "That makes the neighbors and our own workers a lot happier," observes Marie Audet, the Blue Spruce bookkeeper and wife of one of the three brothers who jointly own the farm. "It used to be we'd never have social gatherings on the farm when the spreading was going on. It just stank too much."
The 100-foot-long, 72-foot-wide digester is about as inconspicuous as a big block of concrete can be. Its off-white surface protrudes only a few feet above ground level. And it provides still more benefits for the farm and its surroundings.
All of Blue Spruce's wastewater gets pumped into the digester along with the tons of manure. The seasonal spreading of fertilizer meanwhile results in less runoff into streams because the liquid manure has been thinned to a consistency that seeps into soil more easily. The manure also contains no viable weed seeds because the heating process kills them as well as pathogens that cause Johne's disease, which makes cows waste away.
The whole process delights environmentalists and helps keep an extended Vermont family in the dairy business.
The downside: The digester-generator system isn't easy to operate; nor is it readily replicated.
"They're always tweaking it," Marie Audet says of her husband Eugene and her brothers-in-law Earl and Ernest. The 16-month-old system remains "a work in progress," she adds. "It would have failed if not for their skills for fixing things and keeping them running."
Other manure digesters on New England farms have failed, although several are functioning in the Midwest. The Audets learned from both the successful and unsuccessful models, and spent five years pondering options for improving Blue Spruce's manure management.
"We have a responsibility to do what's right with the waste produced here," says Marie Audet. "None of the other ideas made as much sense to us as the digester did."
Even so, the venture was chancy. The system required a $1.2 million capital investment and, as Audet notes, "There isn't much margin in the milk business."
But the family's entrepreneurial drive has kept Blue Spruce going, and growing, for nearly half a century - a period in which thousands of Vermont dairy farms have been lost. And the three current owners have inherited the willingness to take calculated risks, Marie says.
It helped that Central Vermont Public Service, along with the state and federal government, contributed about a third of the capital costs, leaving the brothers to put up $750,000 of their own money. CVPS maintains a renewable-energy development fund that helped defray the Audets' costs, and it will soon provide a total of $660,000 to four other Vermont dairy farms that plan to install manure digesters and methane generators. Those operations - in Sheldon, Fairlee, West Pawlet and St. Albans - are expected to produce enough electricity to service nearly 1400 average Vermont homes.
The money for CVPS' fund comes from 2500 of the utility's customers who have enrolled in its Cow Power program. They volunteer to pay a premium of up to 4 cents per kilowatt-hour, which amounts to about $20 extra in their monthly bills. CVPS also offers customers the options of a 25- or 50-percent Cow Power surcharge, resulting in about $5 or $10 in monthly increases.
The largest alpaca farm in New England, located in Perkinsville in central Vermont, recently joined the roster of Cow Power participants. In fact, with annual electric use of about 55,000 kilowatt-hours, Cas-Cad-Nac Farm ranks as the single-largest CVPS customer enrolled in the program.
"We're strong supporters of sustainable, Vermont-scale agriculture, so it's a natural decision for us to become Cow Power customers," says Ian Lutz, who with his wife, Jennifer, co-owns the 250-head alpaca farm in Perkinsville.
The added Cow Power payment to the utility is also passed on to the farmers who sell renewable energy to CVPS. The Audets receive about 11 cents per kilowatt-hour for the power they generate - nearly the full 7-cent market price of energy, plus the 4-cent Cow Power bonus sum.
Central Vermont hopes to expand its manure-to-energy program to supply enough power in the coming years for 5 percent of its residential customers. Despite this projected growth and the environmental benefits it entails, says Vermont Public Service Commissioner David O'Brien, "These projects are small steps in resolving our energy future."