Advanced capture configurations for selected pulp and paper plants incl. technoeconomic analysis

Report, 2025

This report presents estimations of CO2 capture and avoidance costs for advanced CO2 capture integration configurations in pulp and paper mills. The report is a deliverable from work package 5 of the ACCSESS project, where focus has been on Stora Enso’s kraft pulp mill located in Skutskär
(Sweden) and Stora Enso’s recycled paper mill located in Langerbrugge (Belgium). The capture technologies considered for pulp and paper mill integration are post-combustion capture technologies using an amine-based solvent (AMP/PZ) and a carbonate-based solvent (CO2 Solutions).

In the Pulp Mill, heat integration opportunities for both capture technologies were evaluated using pinch-analysis tools. The results indicate that the high-
temperature excess heat from the recovery boilers is sufficient to meet the heat demand for capture. However, without additional fuel use, integrating carbon capture in this way would result in a loss in electricity generation. Similarly, in the Paper Mill, it was found that the heat demand for capturing CO2 could only be met by steam extraction from one of the turbines, with a resulting loss in electricity generation.

Comparing the capture cost between the Paper Mill and Pulp Mill confirmed that site-specific factors, such as CO2 flow, concentration of CO2 in the flue gases and the geographical location of the mill, have a strong influence on the capture cost.

Avoiding losses in electricity generation in the Pulp Mill by firing additional fuel for steam generation was explored, leading to the development of several heat integration scenarios. This was done by optimizing the size of a simplified steam cycle to maximize electricity generation either using existing back-pressure steam turbine capacity or investing in extended capacity. Additionally, as pulp mills in the future may look different from today due to strategic developments towards better biomass resource utilization, the cost of CO2 capture in a Pulp Mill with lignin extraction was also evaluated. This cost was found to be higher than for the Pulp Mill without lignin extraction, which clearly indicates that the cost of carbon capture implementation is benefitted by favourable mill energy balances.

A sensitivity analysis assessed the impact of future energy market uncertainties on the capture cost of the heat integration scenarios of the Pulp Mill. At low electricity prices, the results indicate that capture cost does not differ significantly if fuel consumption or co-generation of electricity is
prioritized. In a high electricity price market, on the other hand, investing in extended back-pressure steam turbine capacity, and therefore producing more electricity than the Pulp Mill without carbon capture, clearly achieves the lowest capture cost.

The reboiler heat demand of the CO2 Solutions™ process can be covered by recovering excess process heat due to its lower regeneration temperature. In the Paper Mill, there is limited potential for heat recovery, however in the Pulp Mill, it was found that approximately 34% of the heat demand for capture could, theoretically, be met by excess heat from the mill instead of by lowpressure utility steam. Comparing the capture cost of the CO2 Solutions™ process between the two sites indicate that excess heat availability is an important parameter for achieving a lower capture cost. Of the excess heat potential identified for the Pulp Mill, a single process stream of black liquor flash steam provides 25% of the heat requirement for capture. For the AMP/PZ process, the possibility of upgrading the black liquor flash steam using a mechanical-vapor recompression (MVR) heat pump to meet part of its heat demand was explored where it was found that the potential cost savings from reduced LP utility steam compensate quite well the cost of
investing in and operating an MVR heat pump with a limited temperature lift.

A bottom-up cost engineering approach was adopted to estimate the CAPEX of the capture technologies where “Nth-of-kind” (NOAK) cost factors were utilized, following the assumption that the retrofit will occur in the future, when carbon capture integration with the pulp and paper industry has reached a greater level of maturity. As carbon capture has yet to be demonstrated in the pulp and paper industry, the NOAK cost estimates presented in this work are optimistic compared to expected cost of near-term implementation and should be treated as such.