One of the problems with renewable energy sources like solar and wind is that they are not always available when the power is needed. To smooth out these fluctuations in the availability, an energy storage solution can be coupled with the generation. While batteries are perhaps the obvious choice, hydrogen is also a viable alternative if the cost of producing it (by splitting water) is not prohibitive.
Splitting water into hydrogen and oxygen takes energy, but also a catalyst. That catalyst has traditionally been an expensive metal, like platinum, which has limited its uses.
Nickel & Iron
Researchers at Washington State University have discovered a way to use inexpensive nickel and iron to create a sponge-like nano-foam structure that works as a catalyst and, importantly, it does not lose much of the catalyst material in a 12 hour test. While these are only lab scale tests, it is a promising result.
Aside from having a more efficient way to generate hydrogen for use in fuel cell vehicles, being able to store the hydrogen would allow for a degree of time shifting. During the day, when solar can generate plenty of power, the excess can be used to split water and store the hydrogen. Later in the day, that hydrogen can be used to generate electricity again.