The best evidence is reality. Take a look at the very recent UK example. They have recently gone for 3 weeks with close to zero wind generation.
What was their baseload to replace this missing generation for 3 weeks? It came from the nuclear plants in France. They didn't survive on batteries or pumped hydro for 3 weeks. They are connected to traditional baseload from Europe.
The Snowy 2.0 is planned to be able to run for 7 days. So when we have a 3 week gap in our wind production once we get to that green future, how will we generate power on day 8? What is the backup to Snowy 2.0?
Real backup is coal, gas, diesel ( all of them burn stuff) and nuclear. We don't want to talk nuclear in Australia and coal is totally demonised here. The real baseload left then is gas and diesel. Batteries and pumped hydro both run out after their design hours have expired.
Assume we get to 50% of power coming from wind. There is quite a capital cost there to be recovered. Your plan also includes having combinations of batteries and pumped hydro which also has an additional capital cost to be recovered. Real life experience shows that there can be periods of no wind that can go for weeks. In those circumstances, you then need gas and or diesel that can take the full daily generation load until the wind returns. So that is another 100% of generation capacity capital cost on top of the wind and on top of the batteries and pumped hydro.
The issue is that wind and solar and batteries and pumped hydro all need backup because they all stop completely at certain times. They are simply not the same as gas, coal,diesel and nuclear which can all generate power regardless of the availability of wind or sun or charge capacity or stored water availability.
The sum total of all that capital cost has to be recovered along with any maintenance and operating costs which are higher as you make the systems more complicated.
Please name one country that has rid itself of all traditional baselaods and has no interconnect to such sources when the renewables run out as they all do at various times.
