Would it make sense to actually store it underground, or are the gains minimal when compared to the costs? In general, I'm impressed that there's so much resea

Would it make sense to actually store it underground, or are the gains minimal when compared to the costs? In general, I'm impressed that there's so much research and investment in this field (storing excess renewable energy). I think most people don't realize how much and that the problem of the sun not shining and wind not blowing all the time will be solved much more quickly than most people think is possible.