How long could those batteries power a city the size of...

How long could those batteries power a city the size of Melbourne or Sydney? Do you have an idea the size of battery needed to get Melbourne through a hot night if that was the only source of energy? What happens when the sun isn't shining and the wind isn't blowing with your clean energy?

I have no doubt that one day we will have the technology to go 100% renewable but it won't be lithium batteries that's for sure. I don't think even vanadium batteries can do the job. No matter what the spruikers say, we're still a long way from ditching fossil fuel base load(unless we're willing to go nuclear of course)