Securing adequate freshwater supplies for fossil fuel-fired power plant cooling tower systems is an increasing challenge for operators due to drought and climate change impacts. The evolving transition to plant decarbonization by carbon capture and storage is also expected to significantly increase water consumption and exacerbate water competition with other sectors. An alternative may be at hand in the form of brackish water desalination for power plant cooling needs.

Greater reliance on such nontraditional water sources can help alleviate potential competition for freshwater resources among various sectors in water-stressed regions. However, switching water cooling towers to dry cooling systems at coal- and natural gas-fired power plants incurs additional costs associated with water treatment equipment deployment, which in turn can affect power generation economics.

Researchers from Carnegie Mellon University, University of Wyoming and the U.S. National Energy Technology Laboratory analyzed the technical and economic feasibility of multiple desalination processes for such application. The assessment indicates that retrofitting power plants to treat brackish groundwater could nearly eliminate the use of fresh water but would increase the cost of electricity generation by up to 10%. Zero liquid discharge minimizes environmental impacts of desalination but is particularly costly.

Continued research on the feasibility of exploiting other nontraditional water sources for cooling of power plants, such as treated municipal wastewater and water produced from oil and gas extraction, is warranted.

The analysis of trade-offs in freshwater savings, cost and generating capacity shortfalls from desalination deployment is published in Nature Water.