Strategic responses to CO2 emission reduction targets drive shift in U.S. electric sector water use

The U.S. electric sector's reliance on water makes it vulnerable to climate variability and change. Here we investigate whether carbon mitigation policies would improve or exacerbate electric sector water reliance. We use EPAUS9r MARKAL to model changes in U.S. electric sector water withdrawal and consumption through 2055 resulting from energy system-wide CO2 emissions reduction targets of 10%, 25%, and 50%, as well as nine sensitivity analysis scenarios. CO2 reduction strategies accelerate the deployment of more water-efficient thermoelectric generation technologies and increase the use of renewables, nuclear, and carbon capture. The 50% CO2 reduction scenario also prompts electrification in end-use demand sectors, most notably transportation, increasing electricity demand 36% by 2055. In aggregate, CO2 reduction strategies decrease national electric sector water withdrawal in all scenarios (−31% to −46% by 2055), but have a varied impact on water consumption (−4% to +42% by 2055). These changes in electricity generation technology and the resulting change in water use would likely reduce electric sector vulnerability to droughts and heat waves.