In the renewable energy space, a lot of excitement is building up around green hydrogen. This is a clean way of making hydrogen that does not require carbon inputs and produces no emissions other than oxygen.

Since green hydrogen could be a very lucrative business that would also help countries meet their emission reduction targets, many companies are investing big in this potential future. But how far along is the technology, and what still needs to happen for it to become as mainstream as gasoline or batteries?

Forbes Senior Editor Alan Ohnsman, who specializes in future mobility and energy, visited a few big players in the green hydrogen space to find out.