General Electric researchers at GE’s Global Research Center in Upstate New York are working with the Department of Energy to test a water desalination system that produces fresh water at low cost by using a salt and ice mixture.
If successful, the water treatment technology could reduce the cost of desalination by 20 percent compared to more conventional thermal evaporation approaches, the researchers say.
In power plants, steam turbines use pressurized steam to spin their rotating parts and power generators to produce electricity. As part of the water desalination technology being developed with the DOE, researchers are using the same steam turbine turbomachinery 3D printed in a miniaturized form to compress and stream a mixture of air, salt and water through a hyper-cooling loop that freezes seawater.
By freezing the mixture, the salt naturally separates in solid form, leaving just the ice. The ice is then melted, leaving clean water.
“97.5 percent of the earth’s water supply is virtually inaccessible because water desalination is still too expensive and difficult to deploy at a large scale. By putting desalination ‘on ice,’ we hope to change that dynamic,” says Vitali Lissianski, a chemical engineer and project leader at GE Global Research’s Energy Systems Lab.
While freezing seawater to treat it isn’t a new concept, GE says its process does it differently.
Douglas Hofer, who is leading the development of the turbine technology, says that in a low-pressure steam turbine, water vapor (steam) condenses to liquid water. For the new desalination process, GE team is extending that idea to freeze liquid salt water into solid ice and salt crystals during its expansion through the turbine. This extension from condensing liquids to freezing solids requires new and innovative solutions to address several challenges of this new turbine application.
Analysis of Global Desalination Market, finds that the market earned revenues of $11.66 billion in 2015 and estimates this to reach $19.08 billion in 2019. More than 17,000 desalination plants are in operation in 150 countries worldwide, a capacity that is expected to double by 2020.