Reducing Electricity Penalty of Carbon Capture by Waste Heat Valorization in an Industrial Pulp Mill

Abstract

Industrial CO\(_2\) emissions, particularly from flue gases, are a major barrier to climate change mitigation. Carbon capture, particularly with bioenergy (BECCS), offers a pathway to negative emissions. This study models an MEA-based carbon capture system using operational data from a stand-alone pulp mill, focusing on its energy impact and optimization strategies. The analysis distinguishes between high-quality steam, critical for electricity generation, and waste heat, which can be valorized for carbon capture. The thermal energy demand for capture was found to be 3.6 MJ/kg CO\(_2\), leading to a reduction in energy efficiency. Integration scenarios such as flue gas valorization, combustion air preheating, and a steam generation heat pump (SGHP) were evaluated to address this. The electrical energy penalty (EEP) was introduced as a metric to quantify power losses due to steam extraction. The results show that while flue gas valorization and air preheating offer limited benefits, the steam generation heat pump effectively reduces both steam dependency and electrical energy losses, enabling high CO\(_2\) capture efficiency with minimal impact on mill operations, with the SGHP achieving the lowest EEP of 0.50 MJ/kg CO\(_2\) and enabling a 90% CO\(_2\) capture rate.