3, worst case scenario 100% coal doesn’t exist in any state of Australia, all states have a mix of renewables, gas and coal.
Well strictly speaking I could say there's no coal at all used for power in the NT although someone would then probably point out that it's technically not a state.
Seriously, so long as we don't have people charging EV's during the peak then the power supply side isn't going to be hugely problematic. Ideally charging 10am - 3pm would be a real winner, to the extent there's any zero or at least low emissions energy going to waste that's largely when it happens, and second best would be 1am - 6am since it's not unknown that some wind goes to waste overnight although it's not overly common.
That varies a bit between states by the way but those that aren't there yet are rapidly approaching it as more solar is installed so I won't bother with the detail for those that aren't since it'll soon be obsolete anyway.
Worst time = during the evening peak the absolute extreme of which generally occurs between 6pm and 8pm depending on location, season and weather. The further away from that toward the low demand periods, the better. Reason, apart from any increase in the peaks driving up costs, is that's when you'll find the highest network losses and the least efficient generation running along with the energy losses of getting it running in the first place.
Getting the right approach to charging EV's will make a big difference to all this. It's one of those things where "if everyone does it......" then collectively it's serious power being drawn or not drawn so the timing does matter. Best = fill in the gaps in demand for other purposes. Worst = add to the current peaks. Anything else sits in the middle in terms of impact.
There's a few companies with ideas of doing some clever things in that space by the way. There are some different ideas around, ranging from consumer incentives through to centralised remote control, but they all have the same underlying objectives of filling in the gaps in demand with EV charging and not adding anything to the current peaks.
This can be done, it can be made to work, the questions are about the detail of doing it.
A point to remember though is that from an environmental (as distinct from technical etc) perspective the aim isn't to use electricity per se but to avoid the use of fossil fuels. If an EV isn't an option for whatever reason well a diesel or petrol car getting 5 litres / 100km beats one using 10 litres / 100km and don't even mention those getting 1 mile to the gallon or whatever.
As for me - no EV at present although I made provision for it with some electrical works done last year. My ICE driven car isn't too bad though - uses 7 litres / 100km typically. Not fantastic but by no means the worst car around for fuel consumption.