Comment by pfdietz

Even without natural gas, hydrogen as a general energy storage medium competes against thermal storage. The round trip for this (electrical energy back to electrical energy) can be as good as hydrogen, and the storage medium can be literally dirt cheap, cheap enough that seasonal storage looks like it makes sense, if the design is brutally focused on cost optimization.

Here, corrosion of steel is also part of the problem, as you are burying steel pipes in piles of hot dirt.