Technoeconomic Analysis of Kraft Pulp Mill Integration with an Advanced Nuclear Reactor

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Nuclear power presents a highly efficient and clean energy solution that could meet the energy needs of the pulp and paper industry.In this sense, the U.S. Department of Energy's (DOE) Integrated Energy Systems (IES) program is actively engaged in research, development, design, economic siting, and risk analysis to demonstrate how advanced nuclear reactors can be integrated with existing industrial operations to provide clean energy, thereby reducing CO2 and other emissions.An IES initiative aims to facilitate the first on-site demonstrations and commercial deployments of advanced high-temperature gascooled reactors (HTGRs) within industries such as chemical production, refining, iron and steel manufacturing, and more.The DOE IES program seeks to prove that advanced nuclear reactors can sustainably and cost-effectively meet the heat, steam, and power demands of different industries while significantly cutting CO2 emissions and improving decarbonization.This study focuses on post-combustion capture and oxy-fuel combustion for the boilers at the mill, as well as steam integration with the nuclear power plant (NPP).The primary goal of the research outlined in this report is to design, analyze, and document the integration of an industrial-scale HTGR with a reference kraft pulp mill.The purpose is to deliver reliable, cost-effective, and sustainable clean energy alternatives while reducing CO2 emissions.Specifically, this study focuses on six different scenarios that include carbon capture equipment, and some of them use nuclear power to meet the heat and electricity needs of the reference plant.Two of these scenarios are created while also producing clean hydrogen through integrated high-temperature steam electrolysis (HTSE).This report offers a detailed technoeconomic assessment of different scenarios for a kraft pulp mill, including an analysis of tax credits (sections 45V, 45Q, and 48E) provided by the Inflation Reduction Act (IRA) of 2022.The evaluation explores the potential economic benefits and challenges of incorporating different configurations, including nuclear energy, into kraft pulp mill operations, with particular attention to energy efficiency, economic implications, and environmental impact.By assessing both technical feasibility and economic viability, this analysis aims to identify existing gaps and propose solutions for the successful implementation of nuclear integration.The findings are intended to provide valuable insights for stakeholders considering the adoption of advanced nuclear reactors in the pulp and paper industries.Chemical wood pulping is essential for extracting cellulose from wood, but it contributes significantly to CO2 emissions, particularly through the kraft, sulfite, and neutral sulfite semichemical processes.The kraft process, which dominates U.S. production with over 80% of chemical pulp output, is heavily impactful due to its energy-intensive nature and reliance on fossil fuels for additional steam generation.The kraft process involves the high pressure, medium temperature digestion of wood chips in a solution of sodium sulfide and sodium hydroxide.After the pulping process, the spent cooking liquor is concentrated and combusted in a recovery furnace, which generates process steam and recovers chemicals.However, the steam generated is often insufficient, necessitating the use of conventional boilers fueled by coal, oil, natural gas, or biomass, thereby increasing CO2 emissions.In addition, the lime used in the chemical recovery cycle requires high temperature to be produced, and the technology used to provide the heat required relies mostly on fossil fuels.Decarbonization potential in the chemical wood pulping sector lies in reducing reliance on fossil fuels, enhancing energy efficiency, and adopting cleaner technologies.Transitioning to renewable energy sources for process heating and steam generation, optimizing the chemical recovery process, and exploring innovative pulping methods could significantly lower the sector's carbon footprint.Prioritizing these strategies is critical for reducing the environmental impact of the kraft process and advancing the industry's contribution to global decarbonization efforts.Nuclear integration to pulp and paper operations offers significant benefits, such as cogeneration of heat and power, carbon neutrality, and power source reliability and stability.Hydrogen generation from the integration of nuclear power in the conventional kraft process for producing pulp and paper products can lead to new opportunities that include: (1) using nuclear hydrogen as a fuel source for the lime kiln, or in combination with natural gas or other fuels to decrease its carbon intensity, and (2) assessing alternatives to convert woody biomass (e.g., lignin, bark) to biofuels.Scenarios 4 and 5, when an oxy-fuel combustion retrofit in the boilers is considered, show a potential capacity of more than 200 metric tons of hydrogen production per day.The decarbonization pathways for kraft mills fall into two categories: reduction of fossil fuel use and carbon capture. Nuclear integration: coupling NPPs with the pulp and paper industry has been happening for decades around the globe.For instance, the Gösgen NPP in Switzerland has supplied process steam to nearby heat users, and district heating for nearby municipalities. Black liquor gasification: black liquor gasification allows harvesting black liquor solids, using the energy released from the gasification process in the form of syngas, to be burned in other applications or processed into fuels and chemicals.Some studies show that over the next two decades, a significant number of recovery boilers will be replaced, and a significant quantity of new recovery capacity will be added.The total new recovery capacity is estimated to be 12 million pounds.Benefits of this pathway are described in section 2.1.2. Lignin precipitation: studies show that lignin recovery processes are only profitable for kraft pulp plants if the precipitation increases pulp yields, however, higher lignin market prices and government subsidies can increase the internal rate of return. Hydrogen blend with natural gas: there is a well-established precedent of utility companies blending hydrogen into natural gas through specialized equipment to combust high hydrogen fuel gas blends at a manufacturing plant scale.More recently, some new projects are targeting hydrogen content up to 100%, relying on specialized materials. Carbon-neutral and clean fuels: opportunities exist for fuel switching in the lime kiln unit, which is the only unit in a pulp plant that relies mainly on fossil fuels for normal operation.Co-firing or complete fuel substitution in the lime kiln are technologically feasible with alternative fuels such as tall oil and tall oil pitch, producer gases, hydrogen, bark powder, lignin, and torrefied biomass. Electric lime kilns: electrification offers an alternative to reduce the carbon footprint of lime kilns in the paper industry, however, large-scale demonstrations of this technology are still needed.

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