The whole of TAS is powered by hydro, they export power to VIC. Never heard of the Snowy Hydro scheme in NSW?
As for Tidal, just because Australia isn't currently utilising it doesn't mean it is can't.
I guess you also missed this? https://www.google.com.au/amp/s/reneweconomy.com.au/world-first-south-australia-achieves-100pct-solar-and-lowest-prices-in-australia/amp/
An improvement in battery technology is all that is needed for SA to become 100% renewable, that will happen by 2050.
