Ian McClintock,
Geoff's case may be superficially compelling, but think about it a bit more and you'll see it's actually based on a lack of understanding of the issues. If you think his claims amount to incontrovertible facts, you're very gullible!

Geoff Carmody's expertise in this area seems to consist primarily of spreading anti-renewables propaganda. He has a background as an economist: a profession where getting away with making erroneous predictions based on false assumptions is rife, and he certainly has no qualms about using similarly shoddy calculations here! An obvious example is the calculation of how many renewable power units and how much storage are needed to emulate baseload, instead of the more useful comparison of the amount of storage needed to meet the actual requirements (from renewables v from baseload).

One of the things he doesn't understand is that the cost of renewables has come down a long way, and is still falling. It's no longer accurate to claim coal and/or gas works out cheaper than wind and solar. They have different cost structures so direct comparisons are heavily dependent on assumptions, but the balance is strongly shifting in favour of renewables (and already new coal fired power is uneconomic). And though the current system of cross subsidies makes renewables seem more expensive, it results in more energy coming into the market, lowering the price. It's likely electricity prices here have peaked now.

James Temple's California study is far less significant than Geoff implies. California's wind and solar output is highly seasonal, and (unusually) they're both high in summer and low in winter. I'm skeptical that the difference is really as big as Chart 1 depicts, but even if it isn't, it should be obvious to everyone that batteries are not practical for smoothing out the seasonality. But that's not the only way to reach 100% renewables. Hence Chart 2 is irrelevant even for California, let alone Australia which doesn't share California's seasonality problem.