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What is it?

Concentrated sunlight is used to heat up transition metal oxides (e.g. cerium oxide), releasing oxygen. The metal oxides are then reacted with water, which splits to re-oxidise the metal oxide as well as produce hydrogen – the cycle then repeats.

Why is it important?

This process produces hydrogen using only water and sunlight and has the potential to be low-cost due to system simplicity.


  • Inputs: Water and sunlight
  • By-products: Oxygen
  • Operating temperature: ~900 to 1,500°C
  • Energy efficiency: Theoretical greater than 30%. Demonstrated approximately 5%


  • Less complex and fewer steps than hybrid thermochemical water splitting
  • Does not require an electrolysis step (therefore no electricity input)
  • Zero CO2 emissions
  • Make use of concentrated sunlight as heat source


  • Requires very high operating temperatures
  • Dependent on solar irradiation

RD&D priorities

  • Improve concentrated solar thermal technologies
  • Improve thermal efficiency
  • Improve long-term stability of reactor materials
  • Conduct fundamental material investigations (e.g. understand mechanism of material melting and sticking)
  • Develop overall large-scale system concepts

Known active organisations

  • The Australian National University
  • Flinders University
  • The University of Adelaide
  • The University of New South Wales

Other opportunities like this

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