Water-Related Power Plant Curtailments: An Overview of Incidents and Contributing Factors

Thermal pollution impacts on rivers and power supply in the Mississippi River watershed

“…The study focuses on the Mississippi River watershed as it accounts for the majority (75%) of OT-based capacity that relies on riverine freshwater in the US, most of the curtailment events due to CWA temperature limits when enforced (CWA limits may not always be enforced) and 90% of thermal pollution impacts on power supply (SI available at stacks. iop.org/ERL/13/034033/mmedia) [10,11,[31][32]. Between 1995-2015, 87-128 OT-based plants (66-81 GW) and 179-198 RC-based plants (111-146 GW) were simulated.…”

“…Warm river temperatures and thermal effluents are not only an environmental concern. Thermal pollution is regulated under the Clean Water Act (CWA) section 316(a), which prohibits plants without variance permits from raising river temperatures above threshold limits to the extent that electricity generation may need to be curtailed [11,12]. In addition, OTbased plants rely on sufficiently cool river temperatures to maintain optimal thermal efficiency [13,14].…”

“…The study focuses on summer months when electricity generation is at its peak, river temperatures are warmest and CWA curtailments typically occur [8,11]. Three metric categories are discussed: adjusted available capacity (AAC): the available capacity as a percentage of nameplate capacity accounting for losses or gains in thermal efficiencies due exclusively to changes in condenser inlet temperatures (AAC C ) and the total AAC (AAC T ) accounting for all climate-water impacts and CWA-forced curtailments; plant-to-plant interferences: thermal interferences (TI) and consumptive interferences, when thermal effluents and consumptive water use at upstream plants lower the AAC at downstream plants, respectively; thermal pollution: the length (km) of river reaches where thermal effluents cause an increase of 1 • C-3 • C (TP 1−3 ) or >3 • C (TP >3 ) in river temperatures above natural conditions (as if thermal pollution is absent).…”

Quantification of the water-use reduction associated with the transition from coal to natural gas in the US electricity sector

“…The large volume of water utilized by this sector, compounded with climate change, growing population, degradation of water quality, as well as other factors, may exacerbate future water availability problems [5][6][7]. Reduced water availability could also have important implications for reliability of the electric power sector, as suggested by 18 episodes from 2000 to 2015, when coal plants were unable to generate electricity because of insufficient or high-temperature water supplies [8,9]. In almost all incidents the curtailments happened in the summer months during drought periods.…”

“…Recent reports examining the threats that climate change pose to the future US economy highlight the reduction in CO 2 emissions that could be achieved by decommissioning coal plants [8,12,[17][18][19][20]. Nonetheless, with natural gas becoming the predominant energy source for the electricity sector, the intensification of shale gas production in the US, and the significant increase in the intensity of water consumption of this process [21], raises questions about the implications of the transition from coal to natural gas on water availability.…”