https://www.withouthotair.com/c10/page_62.shtml
16 kWh/day/person for shallow offshore and 32 kWh/day/person for deep offshore
To build enough wind turbines to generate 48 kWh/day per person is estimated to require 60 million tonnes of steel. That's three times the amount of steel that the United States used to build ~2700 liberty ships during the Second World War.
We don't have to generate 48 kWh/day/person for it to make sense to build a mountain of offshore wind.
IIRC his point was basically that you could make a concerted effort to start building nuclear now, and in 10-15 years you'd be there on having non-CO2 emitting power generation, and that if you even let one part of the renewables equation slip (e.g. banning onshore wind which was the case from 2010 onwards), then you still wouldn't have enough to meet total demand. And that in addition, the cost in terms of producing the actual mechanism to generate the power in both money and in materials in concrete + steel was vastly larger in doing it with wind/solar than with nuclear, with a lot more engineering challenges too.
It's even more dramatic between countries, I saw in my previous job that for e.g. a country like India with monsoon season typically curtails it's turbines for a large part of the year.
e.g.
https://www.researchgate.net/figure/European-Offshore-Wind-A...
From wiki:
> Northern Ireland, Wales and western parts of England and Scotland are generally the mildest, wettest, and windiest regions of the UK, being closest to the Atlantic Ocean, and temperature ranges there are seldom extreme. Eastern areas are drier and less windy
But it being very windy isn't really conducive to building wind farms. You want (a) shallow seas (b) stable and continuous wind. That's why if you look at the map of where wind farms are situated they big offshore farms are concentrated on the east coast of England and Scotland, mostly from Norforlk upwards: https://mapapps.bgs.ac.uk/wind-farm-rare-earth-magnets/
It's not that you can't build them on the west, it's just easier.