Can more mooing cows mean more electric power? The owners of one New England dairy say, “Why not?”
The Blue Spruce Farm in Bridport, Vt., is famed for the 3.6 million gallons of milk that its cows have produced annually since 1958. Its cattle are less well known, however, for another bovine byproduct — one you wouldn’t want to consume, let alone smell. One cow produces 30 gallons of manure, and this dairy producer is the first to call it “cow power.” By harnessing methane gas from the manure and burning it in a 600-kilowatt generator, Blue Spruce Farm can produce enough electricity to power 400 homes.
“We wouldn’t run the farm without it,” says Ernie Audet, one of the owners. He adds that, after six years of cow power, the revenue from selling energy back to the grid has nearly paid back the initial $1.5 million investment in the generator.
Cattle often get a bad rap environmentally speaking (especially in drought-stricken California) for methane, which is a byproduct of their digestive system and a greenhouse gas that compromises 14 percent of the atmosphere. But the cow power process transforms a dangerous emission into an asset.
We at NationSwell have long been fans of anaerobic digestion and its ability to turn trash into electric treasure. As a legion of microscopic flora digest waste, they slowly release methane gas which builds up to higher pressures in a 16-foot deep biodigester that looks something like a concrete swimming pool (with murky water) and a concrete cover. What’s unique about cow power is that the biological process in the digestion tank nearly replicates what’s happening in the cattle’s multi-chambered stomach, as bacteria break down tough grains and otherwise indigestible grasses.
The 1,400 black-and-white spotted girls in the barn at Blue Spruce Farm have grown accustomed to their filth being swept away into the biodigester. As they chew on their cud, a scraper runs along the floor, collecting their manure, which Audet and the other owners call “liquid gold.”
“People are always asking us ‘Why don’t all farmers do this?’” the owners write. “Many of us in the dairy industry believe that any size farm can build a digester, and eventually most will. The barriers are the sizable initial investments, and locking in a reliable revenue from the power sales. Operating a Cow Power facility also requires new skills, and more labor. But when a community gets together, these challenges can be met.”