Scaled up, these solar-derived fuel cells would provide an energy storage solution that puts solar power on the same consistent, reliable footing as any fossil fuel.

Various researchers have gotten most of the way there only to get hung up on that little word, “cheap,” but a new study has revealed a pathway that could result in a cost-effective solution.

We’re calling this device an “artificial leaf” but to be more precise, it’s a photoelectrochemical (PEC) cell. In contrast to a photovoltaic cell, which converts light to electricity, a PEC cell collects photons and converts them to energetic electrons, which touch off a chemical reaction splitting water into hydrogen and oxygen gas.

One main hurdle has been the development of a catalyst that is efficient enough, and cheap enough, for such a device to hit a reasonable price point. Plenty of high-efficiency catalysts abound, relatively speaking, but they are far too expensive to make sense.