Hydrological limits to carbon capture and storage

Carbon capture and storage (CCS) is a strategy to mitigate climate change by limiting CO2 emissions from point sources such as coal-fired power plants (CFPPs). Although decision-makers are seeking to implement policies regarding CCS, the consequences of this technology on water scarcity have not been fully assessed. Here we simulate the impacts on water resources that would result from retrofitting global CFPPs with four different CCS technologies. We find that 43% of the global CFPP capacity experiences water scarcity for at least one month per year and 32% experiences scarcity for five or more months per year. Although retrofitting CFPPs with CCS would not greatly exacerbate water scarcity, we show that certain geographies lack sufficient water resources to meet the additional water demands of CCS technologies. For CFPPs located in these water-scarce areas, the trade-offs between the climate change mitigation benefits and the increased pressure on water resources of CCS should be weighed. We conclude that CCS should be preferentially deployed at those facilities least impacted by water scarcity. Carbon capture and storage (CCS) can reduce emissions from coal-fired power plants (CFPPs) but it needs additional power that increases water use for plant cooling. This study models the impacts of retrofitting CFPPs with CCS on water resources globally and finds areas at risk of water scarcity.