Evaluation of cooling requirements of post-combustion CO 2 capture applied to coal-fired power plants

Abstract

Whilst CO2 capture and storage (CCS) technology is widely regarded as being an important tool in mitigating anthro-pogenic climate change, care must be taken that its extensive deployment does not substantially increase the water requirements of electricity generation. In this work, we present an evaluation of the cooling demand of an amine-based post-combustion CO2 capture process integrated with a coal- red power plant. It is found that the addition of a capture unit translates into an increase in the total cooling duty of 47% (subcritical), 33% (supercritical) and 31% (ultra-supercritical) compared to a power plant without capture. However, as the temperature at which this cooling is required varies appreciably throughout the integrated power capture process, it is found that his increase in cooling duty (MW) does not necessarily lead to an increase in cooling water usage (kgH2O/MW). Via a heat integration approach, we demonstrate how astute cascading of cooling water can enable a reduction of cooling water requirements of a decarbonised power plant relative to an unmitigated facility. This is in contrast to previous suggestions that the addition of CCS would double the water footprint.