A Regional Water Resource Planning Model to Explore the Water-Energy Nexus in the Southeastern United States

The power sector withdraws substantial cooling water for electricity generation across the United States and is thus heavily dependent on available water resources. Subsequently, any changes in water supply undermine the reliability of power generation. Problems related to the energy-water nexus are not confined to only water quantities. Power generation typically involves the release of cooling water to nearby surface water resources; the resulting thermal pollution negatively affects eco-systems. This research intends to inform energy policy and decision making in the context of future decisions around type and location of energy generation. Ultimately, this may lead to reduced greenhouse gas emissions and the avoidance of unintended consequences related to water thermal pollution. Different energy management strategies will have different water management implications in terms of water withdrawals and consumption for cooling, and water temperature issues that extend from the local, to the regional, and ultimately to the national scale. Further, the gravity of these impacts will be defined by the individual water systems characteristics within which energy management strategies are implemented. As a case study for exploration of the above issues, the Water Evaluation and Planning (WEAP) software system was employed to represent the water resource systems and water implications of energy production in the Southeastern United States. The WEAP application models surface water availability, stream water temperature implications, and different development pathways under current and future conditions in two basins: the Apalachicola-Chattahoochee-Flint (ACF) Basin and the Appaloosa-Coosa-Tennessee Basin (ACT). The model also represents different energy strategies through scenarios derived from the National Renewable Energy Laboratory (NREL) Regional Energy Deployment System (ReEDS) analysis that is being conducted independently, and for the entire United States. Other development pathways are explored include changes in population growth projections and agriculture water demands. A prime example of when power plant cooling water requirements and water demands interact and add stress to the system is an area of the river on the Appaloosa-Chattahoochee River in the ACF basin between Lake Lainer and West Point Reservoir. This area includes the Atlanta Metro Area which has about four million people and water withdrawals for urban consumption and cooling water for electricity generation occur along the river. Study results indicate that changes in stream water temperature due to releases of cooling water may become an important issue of consideration especially during summer and under low streamflows.