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NREL scientists advance solar thermochemical hydrogen (STCH) production

Perovskite materials may hold the potential to play an important role in a process to produce hydrogen in a renewable manner, according to an analysis from scientists at the National Renewable Energy Laboratory (NREL).

Hydrogen has emerged as an important carrier to store energy generated by renewable resources, as a substitute for fossil fuels used for transportation, in the production of ammonia, and for other industrial applications. Key to the successful use of hydrogen as a fuel is being able to meet the Department of Energy’s Hydrogen Energy Earthshot—a recently announced goal to cut the cost of clean hydrogen by 80% to $1 per kilogram in a decade.

The NREL scientists analyzed solar thermochemical hydrogen (STCH) production, which can be potentially more energy-efficient than producing hydrogen via the commonly used electrolysis method. Electrolysis needs electricity to split water into hydrogen and oxygen. STCH relies on a two-step chemical process in which metal oxides are exposed to temperatures greater than 1,400 degrees Celsius and then re-oxidized with steam at lower temperatures to produce hydrogen.


Ma et al.

It’s certainly a very challenging field, and it has a lot of research questions still unanswered, mainly on the materials perspective.

—Zhiwen Ma, a senior engineer at NREL

Ma is the lead author of a new paper, “System and Technoeconomic Analysis of Solar Thermochemical Hydrogen Production,” which appears in the journal Renewable Energy. His co-authors, all from NREL, are Patrick Davenport and Genevieve Saur.

The paper complements ongoing materials discovery research by looking at the system-level design and techno-economic analysis for integrating possible materials into a solar-fuel platform and supporting the Department of Energy’s HydroGEN program. The material discovery in the HydroGEN program involved machine learning, defect calculations, and experimental work to develop new perovskite materials. The researchers need to identify perovskites capable of handling the high temperatures required while hitting performance targets.


A conceptual solar thermochemical hydrogen production platform. Illustration by Patrick Davenport, NREL

This work shows part of a portfolio of techno-economic analysis focused on hydrogen production pathways each with its own advantages and disadvantages. Electrolysis, for example, is commercially available and the electricity required can come from photovoltaics (PV). The PV cells used, however, only capture a section of the solar spectrum. STCH uses the entire spectrum. The concentrated solar thermal power enables STCH to create the chemical reaction.

Active research to identify the best materials for the STCH process is critical to the success of this method for hydrogen production, the scientists noted.

This research is funded by the Department of Energy’s Hydrogen and Fuel Cell Technologies Office.


  • Zhiwen Ma, Patrick Davenport, Genevieve Saur (2022) “System and technoeconomic analysis of solar thermochemical hydrogen production,” Renewable Energy, Volume 190, Pages 294-308 doi: 10.1016/j.renene.2022.03.108



"at temperatures greater than 1400 degrees Celsius"

Not going to fly using heliostats,


Why are they even investigating this?  The sulfur-iodine cycle beats 50% efficiency at a mere 1000°C.

Of course, the economics of using solar energy for water-cracking are dismal.  You've got the restriction to places with cloudless skies and a lousy capacity factor imposed by day-night cycles, not to mention all the thermal cycling problems.  The best sites for this are deserts, which are notoriously poor in water resources for feedstock.  Nuclear energy can supply heat 24/7/365 and be put where the water and consumers are.


Don't tell me that i will have a permanent headache till 2030 where i will decide what kind of car i will purchase, hydrogen or bev or continu with a 2029 gasser for another 14 years.

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