Water Supply and Demand in the Future U.S. Power Sector

Abstract:

The U.S. power sector withdraws more water for thermal cooling than any other sector in the country, predominantly for coal-fired and nuclear power plants reliant on fresh surface water. Future power sector water use, however, is highly uncertain. Some emerging low-carbon technologies use little water (e.g., wind and solar photovoltaic), while others such as carbon capture and sequestration can have relatively high water use. The generating technologies demanding water will depend on a range of market and policy interactions, and the sources of power sector cooling water might change because of regional constraints on the availability of alternative water source types (e.g., fresh surface water, fresh groundwater, wastewater, brackish surface or ground water). Projecting power sector water supply-demand matching is thus crucial for understanding multisector energy-water interactions. This work examines such relationships in unprecedented detail using the National Renewable Energy Laboratory (NREL) Regional Energy Deployment System (ReEDS), a national electric sector planning model. Where previous work tracked technology-specific water demands in ReEDS, the model now links and constrains technology-specific water supply-demand relationships (e.g., groundwater use by coal-fired units using once-through cooling in Georgia), all while honoring physical and legal constructs relevant to U.S. water management. We explore a range of future electricity scenarios to demonstrate national and regional outcomes for power sector water use to identify and discuss: (1) how and where power sector water sources could change, (2) key drivers for future power sector water use, (3) multisector implications for competing water users. Water outcomes are discussed in the context of broader electricity system planning, operations, economics, and environmental outcomes.