Biogenic carbon capture at pulp mills via sodium spiking and oxy-fuel calcination
Year: 2025
Type: article
Abstract: Over 13 million metric tons of biogenic carbon dioxide (CO2) are mineralized yearly in United States (US) pulp mill recovery boilers as molten sodium carbonate. The mineralized CO2 is released downstream in the rotary lime kiln where it can be captured for permanent sequestration. The use of biocarbon and bioenergy at pulp mills enables the possibility for atmospheric carbon removal when biogenic CO2 is captured and sequestered. We demonstrate the feasibility of capturing biogenic CO2 via sodium spiking coupled with oxy-fuel calcination in the rotary lime kiln at existing kraft pulp mills. Sodium (Na) spiking elevates the Na ion loading in the kraft chemical looping process by replacing chlorine-based bleaching with a highly alkaline bleaching sequence. Chemical pulping processes are modeled and simulated to understand the technical limits of implementing sodium spiking in existing pulp mills. Each 1% of sodium added to the bleaching operations increases the rate of CO2 mineralization by 4%, and the maximum increase in sodium content in the kraft process is 9%. Without sodium spiking, lime kilns' estimated CO2 capture costs are $88 and $63/mt CO2 for air and oxy-fuel combustion, respectively. With the implementation of sodium spiking, the cost of CO2 captured decreases by 41% and 52%, showing costs of $52 and $30/mt CO2 for air and oxy-fuel combustion, respectively. Oxy-fuel combustion reduces the costs of CO2 capture compared to air combustion, but merged deployment with sodium spiking seems to be the most cost-effective pathway to integrate carbon capture and storage (CCS).
Institution: North Carolina State University
Language: English
Subfield: Mechanical Engineering
Field: Engineering
Domain: Physical Sciences
Open Access status: hybrid
Estimated APC paid: $4,100
Funder: U.S. Department of Energy
OpenAlex ID: W4410423531