LEWISTON, Maine — A new analysis by the federal Environmental Protection Agency may be good news for Maine firms that make electricity by burning wood, but some environmental groups are crying foul.

The new EPA analysis, issued last week, suggests how the federal government will count greenhouse gas emissions from wood-fired biomass facilities, and an accompanying memo from a top-ranking EPA official suggests biomass producers will likely get a pass when it comes to strict, new carbon dioxide regulations.

Carbon dioxide is a gas byproduct that comes from burning any carbon-based fuel, including coal, petroleum and wood, and it is largely blamed for the effects of global climate change.

But the new analysis suggests that because wood-fired biomass facilities are fueled with forest byproducts, namely leftover branches, limbs, chips and sawdust, the net impact on the environment is neutral over time.

The analysis involves some complex science that models the amount of CO2 live trees absorb compared to the amount that’s released when they either decompose naturally or are burned for energy.

Live trees and other plants absorb carbon dioxide, but once dead and decomposing they slowly release it back into the atmosphere and soil.

The EPA’s new determination that biomass-generated electricity has no net impact on climate change means the biomass facilities may be exempted from some strict new federal air emission regulations on the horizon. The new analysis comes as the federal government moves to implement the Obama Administration’s Clean Power Plan over the next two years.

“There have been differing definitions in various federal statutes for long periods of time but this is the most clear ruling, decision by the federal government that makes clear that biomass has undeniable climate benefits for Maine and the country,” said Bob Cleaves of Portland-based Biomass Power Association.

The association represents the state’s 10 biomass producers and also advocates for national policy that favors biomass energy.

Maine’s biomass industry includes independent power generators that sell the energy they make onto the New England electricity grid but also co-generation facilities that are operated by some of the state’s paper mills. The mills either sell the power onto the grid or use it for their own consumption, depending on the power’s overall value at the time and the mills’ local demand for energy.

With about 345 megawatts of biomass generating capacity, Maine is the largest producer of that type of electricity in New England and one of the largest in the U.S.

“It does provide reassurance,” said Sarah Boggess, a spokeswoman for ReEnergy Holdings, which employs about 105 workers at its four biomass plants in Maine.

ReEnergy owns and operates facilities in Eustis, Livermore Falls, Fort Fairfield and Ashland.

In all, the industry in Maine employs about 1,300 workers and associated jobs and contributes between $100 million to $200 million a year to the state’s economy, according to the Biomass Power Association.

Boggess said the EPA analysis and subsequent memo issued to states by Janet McCabe, the EPA’s acting administrator for Air and Radiation, recognizes biomass as a solution to the problem of climate change and not contributor to it.

But at least one opponent of biomass energy in the U.S., the Partnership for Policy Integrity, claims that burning trees to produce electricity actually produces more CO2 than burning coal — long considered one of the dirtiest of fossil fuels.

Mary Booth, a Massachusetts-based ecosystem and climate-change research scientist, and the director of Partnership for Policy Integrity, said the McCabe memo essentially ignores the science in the EPA’s own report.

She said the controversy over biomass and greenhouse gas is about net emissions over time. She said the amount of carbon dioxide released when wood is burned is much more than when it slowly decomposes. For burning wood to be “carbon neutral,” she adds, a tree would have to grow back nearly as fast is it can be burned.

“Everyone pretty much acknowledges that it emits more CO2 at the stack than burning fossil fuels,” Booth said. “So how can it possibly be treated as climate friendly?”

Booth said the answer to that question is often that the wood fuels that are being burned would release their CO2 naturally anyway or that they will grow back and “re-sequester carbon that’s equivalent to what you would release by burning.”

Booth said the theory is flawed in it doesn’t consider the time it takes to grow a tree back and the net effect of CO2 being released into the atmosphere by burning isn’t made up for decades or even centuries.

She said the EPA got the science basically right in its analysis until it decided that it would exempt biomass that came from so-called “sustainably harvested” sources and treated as “zero carbon under the state’s carbon plan.”

Booth, who has also closely studied Maine’s biomass industry, said the federal policy looks like it’s set to go completely askew by treating an industry that not only pumps CO2 into the atmosphere but also removes the vegetation that mitigates CO2 emissions a pass. She said biomass should be compared on a level playing field to other energy sources, including no-fuel sources like solar, wind and tidal, and not stacked against other fossil fuels.

“They are receiving renewable energy credits alongside wind and solar, and in some cases are out-competing wind and solar for getting those ratepayer funded subsidies and taxpayer-funded subsidies,” Booth said. “Yet they are filthy, super polluting when it comes to conventional emissions, and they are huge greenhouse gas emitters, too.”

Maine’s energy policies, including the state’s renewable energy portfolio standards, 80 percent of which is made up by biomass energy, are likely to be a priority topic for state lawmakers in the coming legislative session.

How the state will meet the requirements in the federal Clean Power Plan and other changes to the state’s energy policy, including how much of the renewable portfolio should come from which sector and what types of energy will qualify as renewable, will all be issues for debate and legislation in 2015.

Booth called the Maine biomass facilities, “some of the worst in the country.”

But Cleaves, the industry spokesman in Maine, said the EPA analysis and subsequent memo “is just a huge win for us.”

“It validates our industry; for years, because of people like (Booth), they have been out there saying things about the industry that have no basis in science,” Cleaves said. “So for the EPA to emphatically and clearly say that sustainable biomass should be supported and promoted in the United States is a very good thing.”

Scott Thistle

Scott Thistle is the State Politics Editor for the Lewiston Sun Journal. He has covered federal, state and local politics in Maine for nearly two decades.