Treatment of brackish water for fossil power plant cooling

Abstract

In this study, we evaluated the technical, economic and environmental impacts of retrofitting brackish groundwater treatment systems at existing coal- and gas-fired electric generating units (EGUs) to reduce freshwater consumption in wet cooling towers. Based on fleet averages, retrofitting brackish water treatment systems decreases unit freshwater consumption by 94–100%, while increasing the cost of electricity generation by 8–10%. The unit capacity shortfalls are less than 1.1%. The resulting cost of freshwater consumption savings by brackish water treatment is US$1.7 m−3 and US$2.9 m−3 on average for coal- and gas-fired EGUs, respectively. However, these trade-offs are highly affected by the brine disposal method. The use of thermal zero liquid discharge for brine disposal can roughly double the average cost of freshwater consumption savings. The cost-effectiveness of brackish water treatment compared with dry cooling deployment depends on how concentrated brines are managed. The identified trade-offs and their dependence fill knowledge gaps to better inform water management. This study reveals trade-offs in freshwater savings, cost and capacity shortfalls from deploying treated brackish water for wet thermoelectric cooling, as well as its cost-effectiveness, relative to dry cooling retrofit, in saving freshwater.