One of the chief advantages of electrolysis is that it can be applied at a great range of scales as a candidate for largescale renewable energy storage. Renewable sources provide a variable output which is difficult for the electricity grid to accept while maintaining its stability, and this places a real and fundamental limit on how much of this energy can currently be incorporated into the supply.

This limit can be circumvented if the renewable energy can be stored at times of excess production, buffering the effect of variability on the grid and providing a more predictable supply. But energy storage at the scale needed for a global shift away from carbon is a significant technological challenge that cannot be satisfactorily met with existing technology. Using clean electricity to drive water electrolysis and produce hydrogen or to drive CO2 electrolysis to produce hydrocarbon fuels in large quantities as an energy storage medium is in fact one of the most viable options available to us.