Effects of environmental temperature change on the efficiency of coal- and natural gas-fired power plants

Abstract

Modeling studies predict that droughts and hotter water and air temperatures caused by climate warming will reduce the efficiency (eta) of thermoelectric plants by 0.12-0.45% for each 1 degrees C of warming. We evaluate these predictions using historical performance data for 39 open- and closed-loop coal and natural gas plants from across the U.S., which operated under daily and seasonal temperature fluctuations multiples greater than future average warming projections. Seven to 14 years of hourly water (T-w), dry-bulb air (T-a), and wet-bulb air (T-wb) temperature recordings collected near each plant are regressed against efficiency to attain estimates of Delta eta per 1 degrees C increase. We find reductions in eta with increased T-w (for open-loop plants) up to 1 order of magnitude less than previous estimates. We also find that changes in eta associated with changes in T-a (open-loop plants) or T-wb (closed-loop plants) are not only smaller than previous estimates but also variable; i.e., eta rises with T-a or T-wb for some plants and falls for others. Our findings suggest that thermoelectric plants, particularly closed-loop plants, should be more resilient to climate warming than previously expected.