> solar and wind anticorrelate more than you think

They anticorrelate in some locations. In others, they don't. Here in Finland in the winter you get effectively zero sun. We also get persistent stationary anticyclones. That means potentially over a month of temps in the -30°C region, and zero wind.

Australia is extremely sunny. California is even better, they are modeling that assuming they keep their current hydro capacity, they only need to add ~3h in batteries. Hot places also do better than cold places, because the usage peaks track the sun.

> In Europe or America you might need 7-8 while in carbon industry PR models (the same people who denied global warming) seem to think you need 300+.

How on earth do you expect 7-8 to be enough? 300 isn't enough either. The real number for a fully renewable-based grid here is somewhere north of 2000.

Renewables are great in some situations. There are places in the world that should go for 100% renewables as quickly as possible. It also makes sense to locate a lot of the high-consuming industry in such places. But before you hawk your solution everywhere, you need to actually study the local conditions, and not try to extrapolate anything from Australia.

>They anticorrelate in some locations. In others, they don't. Here in Finland in the winter you get effectively zero sun.

Virtually nowhere gets zero sun.

Finland is also unusually blessed with tons and tons of hydropower potential which functions both as a battery as well as power generation.

As well as a very low population density.

It is also possibly the best advert for not using nuclear power ever given the disaster of recent projects (e.g. EDF cost overruns).

I think it also depends on other stuff. Spain gets bunch of sun even when there's the deepest winter in Finland but even if they are technically part of the same grid, the challenge is getting the energy there.

> How on earth do you expect 7-8 to be enough? 300 isn't enough either. The real number for a fully renewable-based grid here is somewhere north of 2000.

2.000 hours of storage would equate to 83 full days of electricity demand. That's on its face absurd. Most models assume that a "Dunkelflaute" (span of time with significantly reduced solar and wind output) will last at most 10 days. Add a few days as a safety margin. And that is all of Europe becalmed and dark, as the entire European electricity net is synchronized and transfer capacity between various regional grids is continuously expanded.

Power transmission is a thing. And where you can't lay down a transmission line, you can convert electricity into h2 or methane and put it on ships, just like we do with dino juice.