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Could these cows soon be fueling your home?

Dairy cows graze on the 400-acre Crescent Farm in Haverhill.
Dairy cows graze on the 400-acre Crescent Farm in Haverhill.Mark Lorenz for the Boston Globe

Neighbors of Haverhill’s Crescent Farm will soon notice a change in the air — literally.

The farm, which has nearly 200 dairy cows, will begin construction on an anaerobic waste digester the week of July 10. It aims to begin using the machine to convert manure into renewable methane fuel within seven months.

The digester, the sixth in the state and fourth constructed and managed by Wellesley’s Vanguard Renewables, will convert roughly 100 tons of manure and organic food waste per day. Once it’s running at full capacity, the digester will provide direct power to about 950 homes in the area, said John Hanselman, chairman of Vanguard Renewables.

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“I’m the fourth generation of farmers,” said Crescent Farm’s owner, Michael Davidowicz. “Dairy farming is tough right now, and in order to survive, farms need to find a way to make extra money . . . in almost 37 years, we’ve seen no adjustment in earnings even though the cost to produce milk has increased.”

Davidowicz said the digester will help him heat the buildings on his property, and he plans to sell some of the power to the city of Haverhill, which authorized the project.

The digester works much like an elaborate Crock-pot. Manure and organic food waste from neighboring farms and groceries are loaded into a 100-ton tank, where they are heated at 104 degrees for 30 days. During this time, methanogens — naturally occurring organisms found in the guts and manure of cows — thrive in the heat and consume the waste, emitting methane in the process. The released methane is then harvested, impurities are removed, and the resulting product is renewable, natural gas that can be converted to electric power by a generator.

Hanselman said the digester has the potential to produce more energy than a solar panel because it can run 24/7.

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“A megawatt of solar energy powers about 200 homes, and one megawatt of anaerobic digestion powers about 2,000,” he said.

Hanselman said while the anaerobic digester is fairly new technology in the United States, it’s been used in Europe for years. “The hard thing with digestion is that it’s more complex than solar and wind and much less incentivized,” he said. Unlike Europe, which provides large subsidies and tax incentives for anaerobic digesters, the US has yet to grant the same tax rebate status as renewable solar or wind energy.

“Methane is 20 times more corrosive than [carbon dioxide], and it’s definitely responsible for climate change,” said Hanselman. “So, in a sense, we’re converting nasty methane into happy energy.”

Davidowicz will use the digester byproduct — an organic fertilizer high in nutrients — to grow his crops and certify his 400-acre farm as organic. The leftover solid waste can be pulled out of the digester, dried, and used as bedding for the cows.

Crescent Farm and Vanguard Renewables held three public meetings with the Haverhill Board of Health in order to hear resident concerns and obtain building permits. Davidowicz said residents were initially concerned about the smell and disruption that trucks full of food waste could bring.

“We’ll be putting out a product that smells less than our manure, and won’t be spreading manure in our fields as much,” said Davidowicz. “All of [the waste] will be enclosed, and people won’t be able to see the process going on, because we’ll keep it behind our main barn.”

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By the third meeting, Hanselman said the board and residents unanimously approved the project.

“Thirty percent of food manufactured in the USA goes to waste, and it’s just crazy,” he said. “Knowing that, you’ll never look at a half-eaten cheeseburger the same way. But, the same way that cheeseburger is a threat, it’s also a huge energy provider.”

The waste digestor at Barstow’s Longview Farm in Hadley.
The waste digestor at Barstow’s Longview Farm in Hadley.Vanguard Renewables

Samson Amore can be reached at samson.amore@globe.com.