Here is an enterprising company addressing storage needs for renewable energy.
Renewable energy tends to be intermittent. The sun shines during the daytime only, the wind is not always constant. This creates a huge market to store energy from times of peak energy generation and to release it during time of little generation.
We tend to see a great deal of focus on battery technology, like Tesla’s battery deployments alongside solar installations. In the linked example, a German firm is planning to submerge concrete spheres and to pump water out of them during peak generation. The energy is later released by allowing the spheres to re-fill and generating electricity from the flow of water (like hydro power). In other cases, natural geographical features like (extinct) volcano caldera can be used to store vast amounts of energy in the form of water at high elevations without resorting to batteries.
I’m sure we’ll see a huge variety of methods like this, and these will underpin the global transition to renewable clean energy.