I agree you need much less capacity because you’d usually just want to even out fluctuations, but I think the general gist of the comment is still true: you need just 2,5x the amount of water to produce the same amount of energy. The article says very little about the liquid, and very little about why this would enable them to build this capacity much quicker. A little more data would be nice.

The article in this post is written by yet another dunce who doesn’t know the difference between energy and power. That single generating station would fill 100 MWh of capacity in 37.5 minutes.