[dredmorbius]

Pumped hydro is virtually all deployed grid-scale storage -- 90%+ (and plus quite a bit as memory serves).

It's cheap, effective, scalable, and highly efficient.

It's also got limited sites and localized environmental impacts.

Where you been hiding?

[cwal37]

It is most of deployed storage atm, but the bulk of that wasn't deployed recently. I'm staring at a very informative figure I just made last week that I can't share since it's a draft for a report, but if you glance at EIA 860 data you'll see the breakdown for storage by nameplate capacity is:

Battery - 0.7%

Compressed Air - 0.5%

Concentrated Solar Power Storage - 1.3% (which doesn't always exactly count)

Flywheels - 0.2%

Pumped Storage - 97.4%

You can also see that the average operational year for pumped storage is 1974, not anytime recent. You could weight the years by capacity, but most plants are pretty big, and it shouldn't change it too much. Also, pumped storage capacity only totals 21.6GW.

As for where I've been, I've just been stupidly busy. I keep meaning to jump back in, but I never seem to have the time.