“Solar fuel” is the pretty formula chosen by Al Weimer, professor in the Department of Chemical and Biological Engineering at the University of Colorado to talk about green hydrogen produced using solar energy. This method is called the “thermochemical” approach: it breaks down water into hydrogen and oxygen gas. Traditionally, this decomposition is done by electrolysis and requires considerable energy expenditure. Nevertheless, this process makes it possible to produce hydrogen in quantity, which was not, until now, the case of the thermochemical method. Al Weimer and a team of researchers demonstrated in an article published in the journal Joule that it was possible to apply this famous method under very high pressures, using materials based on iron aluminate – both abundant and inexpensive. Their discovery allowed them to more than double their hydrogen production. A discovery that could pave the way for a more virtuous and commercially viable production of hydrogen, useful in particular in the field of transport and the steel industry.