Hydrogen gas has been the pipe dream fuel of clean-energy advocates for decades. Splitting electrons from H₂ molecules creates electricity and a waste product: pure H₂O. It has the added benefit of being storable (albeit at high pressures or low temperatures), and it can refuel a car or a generator in minutes, as opposed to batteries, which can take hours to recharge.

Unfortunately, most of the hydrogen that is mass-produced today is made by synthesizing it from natural gas (more specifically, methane, or CH₄). But it’s also possible to make hydrogen using electricity and water, using an electrolyzer. If that electricity is renewable electricity, hydrogen can be nearly carbon neutral in its lifecycle.

The problem is that the electrolyzers that can make hydrogen from renewable energy have historically been prohibitively expensive. But that’s changing, according to a new paper in Nature Energy.