Integrating water resources and power generation: the energy-water nexus in Illinois

Thermoelectric power plants contribute 90 percent of the electricity generated in the United States. Steam condensation in the power generation cycle creates a need for cooling, often accomplished using large amounts of water. Negative consequences of power plant water demands, such as dialing down or shutting down, have become increasingly apparent during times of low water availability. Consequently, water constraints can translate into energy constraints. Projected future population growth and changing climate conditions might also increase the competition for water. These water constraints motivate a resource accounting analysis to both establish a baseline of current water requirements and simulate possible impacts from future water and energy management decisions. Furthermore, a potential future increase in the magnitude and duration of droughts and heat waves in the United States motivates a further scenario analysis on the possible impacts of drought and heat waves on power plant cooling operations. The analysis combined existing digital spatial datasets with engineering basic principles to synthesize a geographic information systems (GIS) model of current and projected water demand for thermoelectric power plants. Two potential future cases were evaluated based on their water use implications: 1) a shift in fuel from coal to natural gas, and 2) a shift in cooling technology from open-loop to closed-loop cooling. The results show that a shift from coal-generated to natural gas-generated electricity could decrease statewide water consumption by 100 million m3/yr (32%) and withdrawal by 7.9 billion m3/yr (37%), on average. A shift from open-loop to closed-loop cooling technologies could decrease withdrawals by an average of 21 billion m3/yr (96%), with the tradeoff of increasing statewide water consumption for power generation by 180 million m3/yr (58%). Furthermore, an economic analysis was performed of retrofitting open-loop cooling systems to closed-loop cooling, revealing an annual cost between $0.58 and $1.3 billion to retrofit the 22 open-loop cooling plants in the analysis, translating to an effective water price between $0.17 and $0.68/m3 saved, comparable to current municipal drinking water prices. The tradeoffs associated with these unique water users yield interesting implications for integrated energy and water decision making and policy in Illinois and elsewhere. While there is evidence that a shift from coal-generated to natural gas-generated electricity is economically and politically motivated in the United States, a shift from open-loop to closed-loop cooling technologies is not economically motivated, thus policy would likely need to be the driver