Electric power could bring paper mills to net zero emissions October 15, 2025 Joey Pitchford 5-min. read

A study finds that replacing natural gas with electric and biomass power, along with improved energy efficiency, could help some pulp and paper mills reach zero net emissions.

Researchers began with a simulation of mills defined by two characteristics: whether they used virgin or recycled fibers, and whether they were integrated or not. A virgin mill creates pulp and paper from fresh wood that is being used for the first time, while a recycled fiber mill re-uses readily available fibers which may have been previously processed. A mill is considered integrated if it has the capability to turn wood and other biomass into pulp and paper on site, whereas a non-integrated mill uses pulp that has been produced and dried off site.

“When looking at decarbonization, most prior studies have looked at one product or one type of mill,” said Lokendra Pal, co-author of the study and professor in the Department of Forest Biomaterials and the Department of Mechanical & Aerospace Engineering at NC State. “By building a whole-mill simulation for each of these four categories, we can capture the relative strengths and weaknesses of each. Mixing these different variables lets us understand the tradeoffs and interdependencies of operations in far more detail than has previously been available.”

Virgin integrated mills account for 30% of annual U.S. paper production and 33 percent of greenhouse gas emissions, the largest shares of both between the four types of mills. While these mills produce between 80 and 90% of their energy using waste wood sourced on site, they also typically include a natural gas boiler to provide the remaining necessary energy. Non-integrated mills, on the other hand, do not produce energy on site and rely entirely on natural gas boilers and purchased electricity for heating and drying during the paper-making process. Taken together, the paper industry accounts for 6% of the total U.S. industrial energy consumption, making it the fourth-largest industrial energy consumer.

Researchers found that by moving to electric-powered boilers, these mills could reduce their emissions by as much as 61%, potentially reaching zero net emissions. Doing so would require changes in how electricity is produced, Pal said, so that emissions from electricity production would not cancel out reductions at the mill.

“The electric system in the United States is expected to increase its share of clean and renewable energy by 2050, which would make boilers powered by that electricity much cleaner than using natural gas,” he said. “What we’ve found is that there is a path toward zero emissions for these mills, but only if that progress is made in the electrical grid.”

Researchers also examined the decarbonization effects of using energy-efficient dewatering methods like enzymatic treatments and mechanical presses to remove excess water before the thermal drying process. Drying traditionally involves jetting wet pulp on a moving wire, removing most of the water by gravity and vacuum, and then transferring the wet paper web to press rollers which mechanically squeeze out more water before the paper is passed around steam-heated metal cylinders to boil and evaporate the rest. This heating method, known as thermal drying, is the most energy-intensive part of the papermaking process.

Increasing the water removal during pressing resulted in significant energy savings and reductions in greenhouse gas emissions, said Maria E. Gonzalez, lead author and Ph.D. student in the Department of Forest Biomaterials at NC State. Doing so could have trade-offs when it comes to energy production on site, however.

“We found that each 1% of water removed before drying translated to a 3% increase in total energy efficiency for the papermaking process. However, it also meant less steam production, which is used to power turbines,” said González. “Mill operations are often interdependent, so if you change one process it may impact others. We are trying to overcome the interdependency by offering multiple strategies for mills to pick and choose from.”

The final strategy researchers analyzed was the use of low-carbon alternatives, like using waste wood in boilers instead of fossil fuels. The effectiveness of the method changed depending on whether or not the mill was integrated, but all types saw reductions in greenhouse gas emissions.

Integrated mills benefitted significantly from replacing their limited fossil fuel usage with biomass, especially when electricity costs exceeded that of natural gas. They could also opt to supplement the steam used for powering their turbines with biomass combustion. Overall, this method showed decarbonization rates of between 24 and 48%, depending on how completely the mill replaced its fossil fuels. While these numbers do not reach the emission reductions gained from full electrification, biomass is also a readily available fuel source which could provide mills with higher energy independence, Pal said.

“Looking at all three of these strategies together is a significant step toward improving the sustainability and competitive edge of the U.S. pulp and paper industry,” Pal said. “Trade-offs like this appear no matter what strategy or strategies you use. There is no one-size-fits-all answer to sustainability.”

The paper, “Advancing sustainability in the U.S. pulp and paper industry: Decarbonization through energy efficiency, electrification, low-carbon fuels, and the social cost of emissions,” is published in the Journal of Cleaner Production. Maria E. González of NC State University is lead author of the study, and co-authors include Nelson Barrios and Richard Venditti, also of NC State University. The authors acknowledge support for this work from the Alliance for Pulp & Paper Technology Innovation (APPTI) consortium, which is supported by leading pulp and paper producers and their associated team members.

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Note to editors: The abstract of the paper follows.

Advancing sustainability in the U.S. pulp and paper industry: Decarbonization through energy efficiency, electrification, low-carbon fuels, and the social cost of emissions

Authors: Maria E. González, Nelson Barrios, Richard A. Venditti, Lokendra Pal, North Carolina State University

Published: Aug. 11 in Journal of Cleaner Production

DOI: 10.1016/j.jclepro.2025.146196               

Abstract: The increasing need to mitigate greenhouse gas emissions from the industrial sector requires a clear understanding and effective implementation of decarbonization strategies. The U.S. pulp and paper industry is responsible for 78 million metric tons (MT) of fossil carbon emissions annually across four major mill configurations: virgin integrated, non-integrated, recycle integrated, and virgin-recycle integrated. These mills manufacture diverse products, necessitating specific decarbonization strategies. This study presents a comprehensive analysis of three decarbonization pathways, energy efficiency through improved dewatering, electrification, and low-carbon fuels, tailored to each mill configuration. Distinct energy flows and emission hotspots were identified across environmental scopes: Scope 1 (direct emissions), Scope 2 (purchased electricity), and Scope 3 (external operations). A virgin integrated linerboard mill has the highest fossil fuel share (52 %) in Scope 1, along with 1968 kg CO₂-eq per MT of biogenic emissions. In contrast, a non-integrated tissue mill shows the highest contribution (40 %) from Scope 2. Switching to 100 % biomass fuel reduces total CO₂-eq emissions by 48 % in the integrated mill, while biomass-powered gas turbines can achieve a 38 % reduction in the non-integrated mill. Under a green grid scenario, electrification reduces emissions by 61 % in the non-integrated mill and by 52 % in the integrated mill. However, some strategies present trade-offs across other environmental impact categories. Additionally, the social cost, representing the monetized societal damage from CO₂-eq emissions, was estimated to assess broader implications. Overall, this study recommends case-specific approaches for decarbonizing different mill configurations and highlights the social impact of the evaluated strategies, contributing to the development of a comprehensive strategic roadmap for a more sustainable forest products industry.