Perovskite materials could have the potential to play an important role in a process of producing hydrogen in a renewable way, according to an analysis by scientists at the National Renewable Energy Laboratory (NREL).
Hydrogen has become an important vector for storing energy generated by renewable resources, replacing fossil fuels used for transport, in the production of ammonia and for other industrial applications. The key to success in using hydrogen as a fuel is being able to meet the Department of Energy’s Hydrogen Energy Earthshot target, a recently announced goal of reducing the cost of clean hydrogen by 80% to $1. per kilogram in a decade.
NREL scientists analyzed an emerging water splitting technology called solar thermochemical hydrogen production (STCH), which may be potentially more energy efficient than producing hydrogen via the commonly used electrolysis method. Electrolysis needs electricity to separate water into hydrogen and oxygen. STCH relies on a two-step chemical process in which metal oxides are exposed to temperatures above 1,400 degrees Celsius and then reoxidized with steam at lower temperatures to produce hydrogen.
“It is certainly a very difficult area, and there are still a lot of unanswered research questions, mainly from a materials perspective,” said Zhiwen Ma, senior engineer at NREL and lead author of a new paper, “ System and Technoeconomic Analysis of Solar Thermochemical Hydrogen Production”, which appears in the journal Renewable energy. Its co-authors, all from NREL, are Patrick Davenport and Geneviève Saur.
The paper complements ongoing materials discovery research by examining system-level design and techno-economic analysis to integrate possible materials into a solar fuel platform and supporting the Department of Energy’s HydroGEN program. ‘Energy. Materials discovery in the HydroGEN program involved machine learning, defect calculations and experimental work to develop new perovskite materials. Researchers need to identify perovskites that can withstand the high temperatures required while meeting performance goals.
This work presents part of a portfolio of technical and economic analyzes centered on the hydrogen production sectors, each with its advantages and disadvantages. Electrolysis, for example, is commercially available and the electricity needed can come from photovoltaics (PV). However, the photovoltaic cells used capture only part of the solar spectrum. STCH uses the whole spectrum. Concentrated solar thermal energy allows 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 of hydrogen production, the scientists noted.
“The material hasn’t necessarily been found,” Saur said, “but this analysis is intended to provide some boundaries as to where we think the costs will be if the materials meet some of the targets and expectations envisioned by the research community.
This research is funded by the Department of Energy’s Office of Hydrogen and Fuel Cell Technologies.