The three Rs of the environment — reduce, reuse, and recycle have been the mantra of environmentally conscious individuals and companies for decades.
Emerging best practices, technology, and advanced equipment are now enabling the pulp and paper industry to aspire to bold new environmental targets in order to create a new generation of mills with net-zero greenhouse gas (GHG) emissions.
The pulp and paper industry is one of Canada’s most intensive energy sectors, consuming 19 percent of the industrial sector secondary energy use in the country. The industry has long been aware of the need to reduce its carbon footprint and has been taking steps to improve energy efficiency. The industry currently sources about 60 percent of its energy consumption from biomass, but it wants and needs to go further.
FPInnovations scientist, Enrique Mateos-Espejel, gave a presentation at the Paperweek Canada 2019 conference in Montreal in February titled, “Roadmap Towards a GHG Emissions-free Mill: Energy, Power and New Technologies.” The presentation was co-authored by FPInnovations scientist Tatiana Rafione, and Natural Resources Canada scientists Luciana Savulescu, Etienne Bernier, and Serge Bédard.
“The goal for pulp and paper mills is to minimize GHG emissions. And several years ago, no GHG emissions would have been very unlikely or even impossible to imagine, but we are past the imagination stage and well into the implementation stage,” says Mateos-Espejel.
Road-map to GHG-free mills
The initial action Mateos-Espejel says mill operators must take is monitoring plant operations to determine how much fossil fuel is used and what function it serves. With an accurate picture of fossil fuel use, mill operators are positioned to develop optimization approaches using best practices to evaluate control strategies to eliminate heat and water waste. This second step valorizes excess heat and maximizes its recovery.
The effluent produced by pulp and paper mills has a high concentration of excess heat that is often not recovered. Several mills have already applied solutions to recover that heat and conserve water. Methods can be designed to avoid steam injection and cold water make-up, which permits energy reduction and water conservation, which in turn avoids overflow.
The use of biomass to generate energy is an important step in lowering GHGs. Understanding the types of biomass and their characteristics, such as the level of humidity depending on the biomass supplier, can lead to improved efficiencies in biomass boilers. However, Mateos-Espejel acknowledges that biomass supply differs by region and access to biomass greatly affects a mill’s ability to move towards net-zero GHG emissions.
More radical actions
Two additional measures are what Mateos-Espejel considers more radical steps towards GHG-free mills, considering they both might require a significant capital investment: using biofuels instead of fossil fuels in lime kilns and using emerging technologies. Research is being done on the use of lignin and renewable natural gas as alternative fuels to power lime kilns.
Applying new energy-efficient technologies brings additional benefits. Mateos-Espejel says the emphasis is often on external energy devices such as heat pumps that increase energy recovery. Emerging technologies such as carbon capture hold promise. He cites the example of a Resolute Forest Products mill in Saint- Félicien, Quebec that is implementing such technology to capture Carbon dioxide (CO2). A greenhouse adjacent to this mill will use the CO2 the mill captures.
FPInnovations’ partnership with CanmetENERGY
Mateos-Espejel’s presentation was based on the work FPInnovations and Natural Resources Canada’s CanmetENERGY have done in their joint integrated energy optimization studies. The partners analyze the way heat is used to determine where it can be recovered and better applied throughout mills to increase sales of green power, lower emissions, and support the transition to a low-carbon economy. In just six years, the partnership has identified $55-million in annual potential energy savings and added energy-generating opportunities in 18 pulp and paper mills.
“It’s a progression from incremental to radical changes,” says Mateos-Espejel of the drive towards emissions-free mills. “Net-zero emissions might require radical steps to achieve the goal quickly; other operators might begin with energy optimization strategies and go from there. There’s a sliding scale of what mills can do based on their economic reality.”