I smell a rat with the AEMO chart explanation (the latter one)....

I smell a rat with the AEMO chart explanation (the latter one). I work in the sector and domestic supply contracts are long-term and based on fixed prices (adjusted for inflation). So there should be no link between the domestic coal price and international coal prices.

Furthermore, the average marginal price of electricity is set by the marginal supplier, and would be set by the intersection of electricity supply and electricity demand, not the cost structure of utilities and their various fuel supplies - this is not a cost-plus sector. So the higher figures for Q2 and Q3 are simply because there was a lower supply of electricity in those periods (we know there were coal unit outages) and therefore the marginal price was higher. If I'm correct, this is either very poor market understanding by AEMO, or deliberately misleading. And if I'm wrong, my apologies in advance.

All IMHO only.