Assessing the undesired impacts on water sustainability from climate change mitigation technologies in fossil-based power generation†

This work investigates the water impact of carbon capture technologies employed in coal and natural gas power generation, viz. the integrated gasification combined cycle, oxy-fuel combustion, solid oxide fuel cells and solvent-based post-combustion. The water impact per CO₂ avoided (WICa) metric was developed to understand the tradeoff between water usage and global warming potential, and additionally as a decision-making tool. It relates the impact on available water resources to greenhouse gas reduction over the cradle-to-plant-exit lifecycle by leveraging existing metrics, including the water impact index (WII), water withdrawal, water consumption, water quality, and water scarcity index (WSI). The results show that some carbon capture technologies increase the overall water usage of power generation plants, thereby increasing the water impact per CO₂ avoided. Solid oxide fuel cells and oxy-fuel technology, though not mature in comparison with post-combustion capture, have the least water impact per CO₂ avoided. Furthermore, water withdrawal and consumption are shown to trend with the WII in specific scenarios, implying that, in the absence of water quality and WSI data, the metric's use as a stakeholder decision-making tool remains. The potential to reduce global warming via carbon capture technologies in the power generation industry can create additional water resource challenges for countries if not carefully considered.