Comment by nayuki

I should have explained in my original comment why I think those sentences are wrong. I'll do so now.

> pumped hydro [...] can store thousands of megawatts for days.

You can't "store" a megawatt – because you can only store energy, not power.

But another interpretation is, if you actually store thousands of megawatts (i.e. gigawatts) for days, then at the very least, 1 GW × 1 day = 24 GW⋅h. If we take "a few" to mean 3, then 3 GW × 3 day = 216 GW⋅h. I'm not sure there exists a large enough pumped hydro plant in the world that stores 216 GW⋅h of energy. So I think the article meant to say, "store a few gigawatt-hours to be released over a period of a few days".

> Media reports show renderings of domes but give widely varying storage capacities—including 100 MW and 1,000 MW.

Once again, you can't store megawatts of power, full stop. You can store megawatt-hours of energy. The linked article at Bloomberg said that a project in China is building 600 MW of wind power, 400 MW of solar power, and 1 GW⋅h of energy storage – which is the correct unit.