Wind power works great sometimes, but we need electricity that works all of the the time.

> Nuclear is stagnating at just 10% of global electricity

At the moment the slack is increasingly being picked up by burning coal or oil. That's bad.

About 80% efficiency, and 95% of electricity is stored this way. Burning fossils is of course stupid.

> Pumped storage is by far the largest-capacity form of grid energy storage available, and, as of 2020, the United States Department of Energy Global Energy Storage Database reports that PSH accounts for around 95% of all active tracked storage installations worldwide, with a total installed throughput capacity of over 181 GW.

Wikipedia

Pumped storage requires:

a) quite large height differentials

b) a sizeable lake of water to be filled/emptied when needed.

For most places this simply isn't practical.