Could you share your numbers as well? According to [1], the UK currently needs about 300TWh per year. Lets say we go entirely solar+wind+battery(whatever that means) and assume that battery has to bridge a gap of at most 7 days (meaning no wind and no solar at all during this time, which is at most a few days at a time). This adds up to 300/365*7= 5,8TWh of max capacity. Lets take it safe, round up and say we need 10TWh (which is already not "tens of TWH", but "ten"). [2] Says that grid-scale batteries come at around 350$ per kWh right now. kWh -> TWh is factor 1 billion (10^9), meaning if we want to build 10TWh of storage, it will cost 3,5 Trillion Dollars. Impressive number indeed. But there are multiple asterisks here.

1. This calculation takes into account that there is no exchange with mainland europe and no gas power plants or other sources of power (e.g. hydro or hydro storage). This sharply reduces the need for batteries. 2. Battery costs will fall in the next decades, compared to nuclear, which will take a long time (if ever) until costs will fall.

[1] https://www.statista.com/statistics/322874/electricity-consu... [2] https://docs.nrel.gov/docs/fy25osti/93281.pdf