Yeah, so, the first thing to know about that is ICE is ludicrously inefficient. Spinning all that metal at variable speed with tiny explosions is, unsurprisingly, not the best way to turn high density fuels into energy. The thing ICE had on its side is the energy density, on other metrics it's a bad deal (hence why free charging for EVs is affordable)

So if you have 400MW of ICE cars you don't need 400MW of electricity to replace that, something more like 80-100MW is more like it IIRC. The infrastructure build cost isn't zero, but it's much less than this 150% metric suggests.

"ludicrously inefficient"

No, they're not. They're, as implemented in a car, a ludicrous example of engineering compromises.

Put a hybrid drive methane spark-ignition high compression engine and you'll have similar CO2 emissions from a e-car powered by a thermal plant (the vast majority of our power). It'll cost as much as a Tesla too.

Getting some rough numbers from Wikipedia it looks like most common new cars are sitting around 35% thermal efficiency. I believe a formula 1 engine achieved 50% thermal efficiency recently but the cost of that is obscenely high. Where as electric motor efficiency easily hits 90%+.

I'm curious, is that only non-point-to-point personal transportation or does it include all forms (e.g. ocean shipping, rail, public transport)?

That’s very good point, looking at my source the answer appears to be “everything”. I will try to remember that in future.

However, my point is only that we will need non trivial increases in electricity production, rather than any specific number. That point still stands.

You could have a solar farm and some batteries close to each stations. It's not trivial but it isn't a bottleneck either.

When I ran the numbers for the USA, it was something along the lines of adding a 1m wide strip of normal efficiency PV alongside the entire length of the interstate network. I’ve not looked at the size of any other highway system relative to population density but I do know that Denmark gets less sunlight than the USA average.

Like I said in my original comment: I’m optimistic, I just don’t think it’s trivial.

To put it another way, I think it’s something that requires a government rather than being achievable purely with the private sector. That might mean just incentives and template plans, or it might require government to commission things, but it’s that sort of scale.