Water-energy-carbon nexus: A life cycle assessment of post-combustion carbon capture technology from power plant level

Abstract

Carbon capture and storage (CCS) technology is widely regarded as an important strategy to limit CO2 emissions from point sources, especially for coal-fired power plants. However, current CO2 capture technologies are energy-intensive and require substantial cooling capacities. The extensive deployment of CCS technology increases the energy and water stress in power sectors. This study considers a plant level nexus approach to assess the relationship between water, energy consumption, and CO2 emissions of four types of available post-combustion carbon capture power plants from life cycle perspective. It is found that the integration of CCS translates into an increase in life cycle primary energy demand (PED) by 21–46% and water resources depletion by 59–95% compared with the reference power plant with wet cooling tower system, where the membrane-based system exhibits the best performance. However, the life cycle GHG reduction rate reduced to 65%–70% at 90% capture rate. The life cycle energy and water cost of GHG mitigation were quantified as 3.06–7.32 kJ/kg CO2-eq and 1.72–3.00 kg/CO2-eq, respectively, demonstrating the presence of sharp trade-offs between GHG reductions and energy demand as well as water consumptions for carbon capture technologies.