The Effect of Ambient Air and Water Temperature on Power Plant Efficiency

Abstract

The performance of thermoelectric generators depends on a variety of factors, many of which are meticulously controlled through generator design or operational management. However, there are environmental factors that affect operations which cannot be controlled directly, such as air temperature and water temperature. Recent studies have suggested that a warming climate will have a significant impact on cooling water availability for generators, arising in part from cooling water regulations designed to protect aquatic ecosystems. Other work has shown the effect of either air or water temperature on the efficiency of specific generating technologies. The physical relationships between ambient temperatures, combustion, and cooling processes are well understood, but the implications of these relationships for real-time plant efficiency across power generating technologies have not been fully explored in the literature. This study develops empirical estimates for the impact of air temperature and water temperature on the efficiency of coal- and natural gas-fired power plants with once-through and recirculating cooling systems. Using USGS and NOAA air and water temperature data and EPA records of power plant fuel consumption and power output, this master’s project quantifies the impact of air and water temperature on power plant efficiency. Regression models developed here indicate that a 1° C increase in air temperature is correlated with a 0.01 percentage point decrease in plant efficiency and a 1° C increase in water temperature is correlated with a 0.02 percentage point decrease in plant efficiency, though these vary for by generating technology and cooling system type. These impacts are substantially smaller in magnitude than analogous effects quantified in previous studies.