Power-to-Water Battery


Novel, versatile battery that stores surplus renewable-generated electricity as thermal energy and discharges it for rapid, scalable and sustainable atmospheric-water harvesting or humidity control.

  • Power-to-Water Battery 0
  • Power-to-Water Battery 1
  • Power-to-Water Battery 2
  • Power-to-Water Battery 3
  • Power-to-Water Battery 4
Research completion
Commercialisation opportunities
Technology licensing agreement
Problem addressed

Energy storage system (ESS) can bridge the mismatch between renewable energy (e.g., wind power, solar power) supply and end-users’ demand.

  • The surplus renewable electricity from the grid can charge the thermal storage medium via heat pumping or joule heating (e.g., ohmic, induction, microwave).
  • The low-cost, environmental-friendly, and high-storage-density medium (e.g., fire brick, molten salts, stones, concrete, paraffin, etc.) stores the excessive renewable energy in a well-insulated container.
  • The concentrated hygroscopic solution can absorb the atmospheric moisture or the indoor humidity driven by vapor pressure.
Key impact
  • The module structure is simple, and the working fluid is stable. The deployment does not rely on any specific terrain.
  • The microporous polymeric membrane features high specific areas that contribute to high mass flux in a compact structure.
  • The TES materials feature high energy storage density which is a benefit to achieving a low energy loss and thus high efficiency.
  • The high temperature and active heating strategy enable a higher initial concentration and thus faster sorption kinetics compared with the state-of-art AWH modules.
  • 48th International Exhibition of Inventions Geneva (IEIG) - Gold Medal
  • Atmospheric water harvesting (AWH)
  • Humidity control (dehumidification)


  • PWG/PA/1424/2/2023 (USA) Patent number: 63/486,657 (USA)
City University of Hong Kong (CityU)

As one of the fastest growing universities in the world over the past decade, City University of Hong Kong (CityU) is recognised as a hub for innovation in research and professional education. CityU identifies solutions to critical global challenges by extending the frontiers of knowledge both within and beyond existing research paradigms.

The University’s highly qualified academics are drawn from all over the world, not only bringing a wealth of research and professional experience to the teaching programmes, but also contributing to the knowledge and technology advancement.