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Energy: Supply, Demand, and Impacts 247Compounding Impacts of DroughtBox 12.1Delivery of electricity may become more vulnerableto disruption due to climate-induced extremeheat and drought events as a result of:• increased demand for home and commercialcooling,• reduced power-plant efficiencies due to hightemperatures,• reduced transmission-line, substation,and transformer capacities due to elevatedtemperatures,• potential loss of hydropower production,• threatened thermoelectric generation due tolimited water supply, and• threat of wildfire to transmissioninfrastructure.Figure 12.5 Compounding impacts of drought on energy. combined-cycle power plant (dry cooling) capacity drops 0.35% per °F rise in ambienttemperature. Using these assumptions, climate change projections suggest natural gasthermal power plant capacity in California could drop on average between 2% and 5%,and as much as 6% during hot summer afternoons by the end of the century. Duringpeak load periods, reserve margins can be low and natural gas power plants are runningnear capacity.