Dry cooling retrofits at existing fossil fuel-fired power plants in a water-stressed region: Tradeoffs in water savings, cost, and capacity shortfalls

Abstract

This study investigates the performance, cost, and generating capacity impacts of switching from wet cooling towers to dry cooling systems to reduce the consumptive water use at existing fossil fuel-fired power plants in a water-stressed region. Retrofit analysis of dry cooling is conducted on a unit-by-unit basis for both coal-fired and gas-fired power plants. Unit-level results are then aggregated to the regional level. Based on regional averages, retrofitting dry cooling systems in lieu of wet cooling towers decreases total annual plant water consumption at existing coal- and gas-fired power plants by 93% and 100%, respectively, while increasing the levelized cost of electricity generation by approximately 12% and 18%, respectively. Based on a nominal regional water price, this cost increase corresponds to an average cost of consumptive water savings of $2.5 and $5.9 per cubic meter of water saved at coal and gas plants, respectively, if retrofit difficulty is minimal. Over the course of a year, the change in monthly net regional generating capacity from dry cooling retrofits exhibits a seasonal pattern, with the largest shortfalls occurring in July. The average monthly reduction in net capacity is estimated at 0.7% and 1.2% of the regional nameplate capacity for coal- and gas-based plants, respectively. Dry cooling retrofits thus lead to tradeoffs in water savings, cost, and capacity shortfalls, which vary with power plant characteristics. The tradeoffs identified here can fill existing knowledge gaps to better inform electric power industry water management policies, planning, and decision-making in water-stressed regions.