Water storage is great, the cat's meow ... in places where water is plentiful. But there are HUGE tracts of land in the world where there isn't any water. But people still need the energy, when the winds are calm and the skies are cloudy.

Only other kinds of gravity batteries will do, so they're a necessity, especially near remote wind-farms.

"Energy Vault’s gravity-based solutions are based on the well-understood physics and mechanical engineering fundamentals of pumped hydroelectric energy storage, but replace water with custom-made composite blocks that can be made from low-cost and locally sourced materials, including local soil, mine tailings, coal combustion residuals (coal ash), and end-of-life decommissioned wind turbine blades."

"The 100 MWh gravity-based EVx system is being built adjacent to a wind farm and national grid site in Rudong, Jiangsu Province located outside of Shanghai to augment and balance China’s national energy grid...."

https://www.businesswire.com/news/home/20220505005467/en/Ene...

"China's $1bn bet on gravity to store massive amounts of green energy "

https://www.rechargenews.com/energy-transition/chinas-1bn-be...