Are there some shortcomings that I am missing here?
Yes there are a couple of things you have missed.
Firstly I will deviate slightly from your question but I believe this is relevant.
The need for localised storage has only relatively recently become desirable. With the increase of large scale Solar and in particular wind farm projects the need for localised energy storage has become a priority. Despite what the Sales people wish to tell you or what propaganda environmental groups or Governments wish to spout Renewable energy IS NOT A SUCCESS, because a large number of fossil fuel plants have to remain running 24/7 to take up the load on the GRID when the wind drops or the sunshine disappears.
Hydro storage solutions cannot be compared as they are an older technology originally developed to solve the problem of water consumption in areas where the terrain was ideal but the flow of water was insufficient for hydro power generation. They also seldom meet the need for localised storage where the power is wind or solar generated.
So to repeat localised power storage is a relatively new requirement. Hence the lack of solutions.
The main points you have missed are the
Time The Big one of course is time. Gravity batteries are time limited. The length of time a gravity storage unit can resupply the grid on loss of renewable energy supply is quoted as 8-16 hours by Energy Vault. This is a relatively short period of time compared with how long the wind could crease to blow and 16 hours of relatively low sunshine in winter months is not exceptional. 284
Therefore Fossil powered generation would still be needed 24/7.
Capital costs associated with building both the renewable energy sources and the localised storage. Whilst running costs for both are negligible (Charging of localised storage being affected by energy that would have "gone to waste"). However the interest payments on loans secured to build the facilities will add to the running costs.
Environmental costs The effect of wind farms on the scenic environment has already become the focus of fierce opposition in many locations and Gravity storage solutions will be even more detrimental to the landscape.
Location Again linked with environmental but also with the renewable energy sources. Energy Vault depicts a gravity storage tower in the mist of a group of wind turbines. The siting of which would play havoc with the wind required to generate the power to be stored.
Reliability of Power Supplies. The increase in use of renewable energy will eventually bring the whole Power grid system into a state of Chaos. Traditional generation techniques cannot match the running costs of renewable energy sources. However renewable energy sources are not reliable. So in Countries where the electricity supply is not state owned how will corporate bodies manage these discrepancies? How will fossil fuel generation remain viable whilst most days of the year consumers are buying low cost, locally generated, renewable energy? 284