“In Maine, there are several plants that are still burning coal and… tires,” said Courtney Bernhardt, EIP’s director of research who co-authored the report. “We wanted to raise awareness about that.”

The group analyzed greenhouse gas emissions from 185 paper plants across the country, which Bernhardt says are undercounted by federal estimates because of a loophole in the reporting process: the U.S. Environmental Protection Agency doesn’t include greenhouse gas emissions from “biogenic” fuel sources like biomass or black liquor, a wood byproduct of the chemical papermaking process, both of which mills burn to power their operations and can be dirtier than coal.

The agency’s rationale for excluding those sources from total emissions estimates in its Greenhouse Gas Reporting Program, according to EIP, is “because trees can grow back in the future” and offset the carbon emissions from biomass fuels.

Until the EPA accurately reports and regulates all facility emissions, mill owners will have less of a reason to pursue energy efficiency upgrades that can both cut back reliance on dirty fuels and maintain profits, the report claims.

The study’s recommendations for tightening limits on the paper industry’s emissions come as the Trump administration eyes drastic rollbacks of federal rules curtailing greenhouse gases and hazardous air pollutants released by American power plants, according to reporting from The New York Times.

Maine is home to two of the last remaining paper plants in the country that burn tires as fuel. As other mills move away from so-called “tire-derived fuels,” Maine plants have increased their use in recent years, adding to their output of harmful pollutants.

The combination of coal, tires and other fuels burned by ND Paper’s plant in Rumford made it the second-largest emitter of mercury out of the 185 facilities included in EIP’s analysis of 2023 EPA data. The Sappi Somerset mill in Skowhegan, which also burns tires, was a top-20 emitter of hazardous air pollutants in 2020.

Both plants’ emissions have local and global effects. Common mill byproducts like nitrogen oxides, sulfur dioxide and fine particulate matter all harm the respiratory system and can linger in the atmosphere, where nitrogen oxide creates acid rain.

When biogenic fuel is taken into account, mill greenhouse gas emissions are almost as high as the dirtiest U.S. oil refineries, according to EIP. Sappi Somerset mill’s total greenhouse gas emissions balloon from 316,000 metric tons of carbon dioxide to nearly 1.6 million when including biogenic fuel sources — a 400 percent increase.

Nationwide, EIP found that paper mills’ greenhouse gas emissions were 350 percent higher than public-facing EPA estimates.

At the state level, these emissions are counted. Maine ditched the EPA’s model and began including biogenic sources of carbon dioxide in a 2022 update on its climate change goals.

Maine lawmakers recently codified a new 2040 deadline to reach net zero carbon emissions, and one effective way to do so nationwide, according to Bernhardt, is upgrading the inefficient boilers that many mills have relied on for decades to power operations.

The EIP report estimates that 40 percent of all analyzed pulp and paper mills have a boiler that is at least a half century old, including the power boiler that Woodland Pulp’s Washington County mill still uses 54 years after it was installed.

A representative for Woodland Pulp said that the company’s Baileyville mill has reduced its emissions over the past two decades by switching from fuel oil to natural gas. Mill energy needs are also supported by on-site hydropower.

Although many boilers are upgraded and retrofitted to add pollution controls — including the one used by Woodland Pulp — EIP recommends replacing them with zero-emission industrial heat technologies where possible, reducing overall emissions and the amount of heat lost by inefficient boilers during the papermaking process.

Sappi has pursued similar efficiency updates at its Somerset mill in recent years, according to Sappi communications manager April Jones. The company no longer burns coal and has reduced reliance on other dirty fuels, setting a 2030 deadline to reduce the mill’s 2019 greenhouse gas emissions by 41.5 percent per ton of product.

Sappi and Woodland Pulp also disputed EIP’s claims that their total mill greenhouse gas emissions are underreported. Despite EPA’s reporting framework, both companies stated that they still publish their mills’ biogenic emissions. (ND Paper did not respond to requests for comment).

The paper industry hasn’t yet been targeted by rollbacks on hazardous air pollution limits the same way power plants have, according to Bernhardt, but broad changes in emissions regulations could impact industries across the board. Further greenhouse gas reductions may instead have to come from paper companies deciding to invest in clean technologies and reduce pollution.

“There’s a real role for paper to play in a more sustainable economy,” Bernhardt said. “It really comes down to dollars. Can companies afford it?”