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

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.