Seawater holds enormous potential for green hydrogen production, but realizing that potential remains far from straightforward. Direct seawater electrolysis can damage electrodes, whereas conventional freshwater electrolysis loses much of its energy as low-grade waste heat. Researchers have now found a way to harness this otherwise wasted heat, using it to desalinate seawater and produce fresh water alongside hydrogen.

In a study published in Nature Energy on Sept. 15, a team led by Prof. Deng Dehui and Associate Prof. Liu Yanting from the Dalian Institute of Chemical Physics (DICP) of the Chinese Academy of Sciences (CAS) proposed a “seawater to hydrogen and fresh water (STHW)” route that couples alkaline water electrolysis (AWE) with low-temperature vacuum distillation desalination.

The STHW process uses waste heat generated during AWE to drive low-temperature seawater desalination, producing fresh water for electrolysis and external use. The resulting concentrated brine can also be used for resource recovery, including salt, uranium and bromine.