At Peaks Renewables in Clinton, millions of gallons of cow manure gets trucked in from nearby farms and pumped into a 125,000 gallon holding tank.
From there, the liquified waste gets piped into an anerobic digester the size of a football field.
Manure cooks for about a month. Remaining solids and liquids are filtered out and returned to farmers for livestock bedding and fertilizer.
The gas gets pumped into a refiner that scrubs out impurities such as carbon dioxide and hydrogen sulfide.
Finally, the end product — 90% methane — is ready to get piped into homes, said Peaks Renewables president Angus King III, son of the sitting U.S. Senator.
"Instead of buying gas from Pennsylvania or Russia or wherever else it happens to come from, it's coming from right here, which I think is a pretty exciting thing," King said.
Maine has no known fossil fuel reserves. But it's found a way to produce pipeline-quality natural gas.
Companies are transforming methane emissions from cow manure and decomposing trash into so-called renewable natural gas, often touted as a way to curb climate-warming pollution.
But environmental critics argue the promise of homegrown gas is being oversold. Bringing more gas online just tethers consumers to pipeline infrastructure, at the time Maine should be focused on new, nonpolluting energy sources, according to critics.
Peaks Renewables' $25 million digester runs on manure from about 6,000 cows.
Cow manure emits methane, a greenhouse gas 80 times more potent than carbon dioxide. And it typically sits in big farm lagoons, polluting the atmosphere.
King said that’s putting a valuable resource to waste. The Clinton plant makes enough gas to fuel about 2,500 homes, almost half the residential customers of its parent company, Summit Natural Gas.
"So it's really taking advantage of the infrastructure we have, taking advantage of the heritage farming that we have, and capturing those emissions and then putting them to beneficial use," King said.
Meanwhile, an hour up I-95 in Old Town, a subsidiary of British Petroleum called Archaea Energy quietly started processing gas from the state-owned Juniper Ridge Landfill this year.
At full capacity, it could provide enough energy to heat 11,000 homes, according to Jeff Weld, spokesperson for Casella Waste Systems, the private company that manages the landfill.
Juniper Ridge was Maine's single largest recorded source of methane emissions in 2022, according to the state's most recent greenhouse gas inventory.
Gas from the landfill is captured and then burned off, instead of being allowed to freely emit, Weld said.
"The fact is, methane has a high energy quality, high value," Weld said. "We can take that methane, turn it into something that has high energy value and and put it to a better use than simply flaring it."
Bangor Natural Gas has agreed to connect the landfill refinery to its network with a pipeline. Weld says until that’s finished, gas is getting trucked to a pipeline in Eliot, 200 miles to the south.
Regulators recently decided it was in the public interest to expand Juniper Ridge by 60 acres and add 11 years to its lifespan. Expanding the facility has met with fierce opposition from environmental groups, the Penobscot Nation and local residents.
Weld argues extending the landfill's lifeline won't encourage filling it up to try and extract more gas.
But opponents disagree.
"Landfills are bad for human health. They're bad for the environment. They're bad for the climate," said Emily Green senior attorney for the Conservation Law Foundation.
Gas production just incentivizes landfilling, which is supposed to be the last resort for waste disposal in Maine, Green added.
The whole idea that renewable gas is a cleaner alternative is misleading, Green said. Regardless of its source, consuming gas produces carbon dioxide, at the same time Maine is trying to slash greenhouse gas emissions.
"Slapping that green or renewable or eco label on there doesn't change that fundamental premise, which is you are burning methane to to heat homes. And that's a problem," Green said.
And adding gas sources means using, or expanding, pipelines that leak methane into the air and homes, risking the environment and human health, said Jack Shapiro, climate and clean energy director at the National Resources Council of Maine. Shapiro said consumers could be paying for that infrastructure well into the future.
"Every time we switch over to a gas system, we're sort of locking in pollution for years to come," he said.
Maine has the third-lowest per capita gas use in the U.S.
But even if every waste source in the state was tapped into production, they could only supply a third of the state's annual demand, according to projections from the American Gas Association.
Dylan Chase from the Coalition for Renewable Natural Gas acknowledges the resource has limits. But it is growing by leaps and bounds nationwide.
"Awareness around methane is starting to grow, and I think with that wider uptake of RNG as a solution to manage methane," Chase said.
Back in 2011, there were just 31 operating plants in North America, Chase added. Today, there are close to 500, with about 400 more in development.
Peaks Renewables says it is trying to contract with more farms increase the plant's output.
Maine Public’s Climate Desk is made possible by Androscoggin bank, with additional support from Evergreen Home Performance, Bigelow Laboratory, & Lee Auto Malls.
