I'm not entirely sure the term "long duration" is correct for this type of energy storage they're talking about, but either way, looks like there's an actual attempt to get more pumped hydro (and other forms of storage) on the Grid.
https://renews.biz/96257/uk-to-launch-l ... ge-scheme/
UK Govt pushes energy storage strategy
UK Govt pushes energy storage strategy
Tesla Model 3 Performance
Oversees an 11kWp solar array at work
Oversees an 11kWp solar array at work