Researchers at the National Renewable Energy Laboratory (NREL) in the US have developed an approach to renewable hydrogen production where perovskite materials play a key role. This new process for producing hydrogen in a renewable way could help replace the huge amounts of fossil fuels used in transportation, as well as in the production of ammonia and other industrial applications.
Hydrogen is increasingly being recognized as an important carrier to store energy generated by renewable resources, and can be obtained from a range of feedstocks using renewable energy sources. Hydrogen as a fuel is also crucial to meeting the Department of Energy’s (DOE) Hydrogen Energy Earthshot initiative, which has the target of accelerating breakthroughs of more abundant, affordable, and reliable clean energy solutions. In addition, it aims to reduce the cost of clean hydrogen by 80% to $1 per kilogram within the next decade.
As reported in the journal Renewable Energy [Ma et al. Renew. Energy (2022) DOI: 10.1016/j.renene.2022.03.108], the study assessed solar thermochemical hydrogen (STCH) production, a water-splitting technology that could be more energy efficient than producing hydrogen using the more common electrolysis method. Electrolysis requires electricity to split water into its hydrogen and oxygen constituents, and is commercially available, with the electricity required able to be produced from photovoltaics (PV).
STCH, on the other hand, is based on a two-step chemical process where metal oxides are exposed to temperatures of more than 1,400oC before they are re-oxidized with steam at lower temperatures to make hydrogen. Although the PV cells used in electrolysis only capture some of the solar spectrum, direct STCH production by water splitting utilizes the whole spectrum of solar radiation, with the concentrated solar thermal power enabling the chemical reaction.
The study complements other research on materials by investigating the design and analysis for integrating potential materials into a solar fuel platform, as well as helping support the DOE’s HydroGEN program. Based on machine learning, defect calculations, and experimental work, the program aims to develop new perovskite materials that can cope with the high temperatures needed while also achieving performance targets.
The study assesses the performance of various STCH materials in the context of a system platform for its technoeconomic benefits and any issues for scaling up STCH. As researcher Genevieve Saur points out, “The material has not necessarily been found, but this analysis is to provide some boundaries for where we think the costs will be if the materials meet some of the targets and expectations that the research community envisions”. Further assessment of the best materials for the STCH process is pivotal to the success of this method.
“This analysis... provide[s] some boundaries for where we think the costs will be if the materials meet some of the targets and expectations that the research community envisions.”Genevieve Saur