Implications of Thermal Discharge Limits on Future Power Generation in Texas

The recent drought in Texas revealed the vulnerability of curtailment for some power plants due to cooling water supplies being too hot. Assessing the risk of reduced operations at thermoelectric power plants associated with thermal discharge limits, as well the potential for cooperation between power plants, can increase the resiliency of the electricity grid in Texas and aid future planning. This evaluation compares the observed effluent discharge water temperatures from thermoelectric power plants in the Electric Reliability Council of Texas (ERCOT) interconnection with Environmental Protection Agency (EPA) discharge temperature limits. Results indicate that at least two major power plants representing over 3,000 MW of cumulative generation capacity have operated at or near these temperature limits in the past. Predicted warming from heat waves, droughts, or climate change might increase ambient air temperature (one of the primary factors affecting effluent temperature) causing even higher derating in the future.We modeled current and future average monthly cooling water effluent temperature for open loop and recirculating cooling pond systems in ERCOT using current climate data and predictions of ambient air temperature, electricity generation, dew point, and wind speed for 2027–2032. While there are some power plants that are projected to be exposed to thermal effluent-related curtailment, we estimate that there is six times as much electricity generation potential available from other existing generators that can meet demand without reaching thermal effluent temperature limits. That is, this work’s analysis indicates that other existing power plants could generate additional electricity to offset the curtailment of the particular power plants at greatest risk from derating to maintain grid reliability.Copyright © 2013 by ASME