The energy mix for east coast and SA is managed by AEMO. You can...

The energy mix for east coast and SA is managed by AEMO. You can see the mix in 5 minute intervals on there website. I look at at several times a day.
AEMO will take all wind and solar power when generated. At 8am this morning wind and solar were 8% ; at 12 noon it's 31% - mainly because solar has kicked in - but later this afternoon solar will be back to zero.
Hydro is mainly used in the morning and evening high demand periods.
On demand energy such as coal and gas are used to balance the grid. This power runs continuously however the amount required alter depending demand.
The grid is running on average 30% renewables and 70% coal/gas.
Nuclear will ultimately replace coal.
It's plain madness to think that our energy mix won't have a base load component as renewables still rely on the sun and wind and there available fluctuatate each day.