the main problem I see is with statements like this:

> Nick Eyre suggests that 100% substitution is non-economic during large demand peaks in winter, so 90% are replaced with heat pumps, and 10% comes from hydrogen.

This is like a typical engineer mistake - solving that last 1% with some unwieldy nonsense that would be best left "unsolved".

hydrogen is a bunch of nonsense. Just use natural gas and/or resistive heat.

I think this is why hybrid cars were created. Because of the range anxiety problem that could be worked around easier ways.