9 years...in the US they would still be fighting in court over the environmental effect on some rare, never seen snow worm or some such.

Decades ago TVA (Tennessee Valley Authority) built a couple of pumped storage units in Tennessee. A pilot plant for proof of concept was built on the Ocoee River, and the resulting full sized project is the Racoon Mountain Pumped Storage Facility. Though it was laughed at before the pilot plant proved the feasibility, the pilot plant was efficient enough that it still operates and makes power 50 years later.

https://www.tva.com/energy/our-power...ccoon-mountain