An interesting piece in E&T.

https://eandt.theiet.org/content/articles/2021/10/spare-wind-energy-could-be-converted-to-hydrogen-to-power-uk-in-winter/

This comes up with a requirement for seasonal timescale storage of energy using hydrogen to reduce the installed wind power capacity in 2050 from 600 GW down to a mere 190 GW.

The full paper is downloadable here:

www.energynetworks.org/.../renewable-hydrogen-offers-best-route-out-of-future-energy-supply-crunches

So 600 GW is one hundred thousand  6MW wind turbines. Assuming that these would need to be separated by 1 km to avoid blocking each other’s wind (is that a sensible guess?) this would require an area of around 300 km x 300 km. Where shall we put them? The proposed 190 GW will require an area of around 170 km x 170 km, still not easy to install, if offshore they would have to be in deep water or floating.

What are the resources required to build them? Figures are hard to find but I have a report from the United States Geological Survey which is a little old but gives weights of various materials per MW. Newer optimised designs may use less, offshore probably uses more.

https://pubs.usgs.gov/sir/2011/5036/sir2011-5036.pdf

Table 5, page 12,  gives 100 tonnes of steel per MW and 400 tonnes of concrete per MW. 

190 GW installed capacity will require 19 million tonnes of steel and 76 million tonnes of concrete. 

Not impossible amounts when spread over a couple of decades, but a lot of energy to pay back.