I believe the situation is even worse than you show in your...

I believe the situation is even worse than you show in your little graphic at the end of your comment, because when that coal plant is running at 100% capacity, all of the fuel cost of $500 is spent on producing electricity. But when the coal plant is running at only 50% capacity, and it is driven up and down to make up the shortfall in power coming from intermittent renewables, not all of the fuel cost is spent on generating power. Some of it is wasted in overcoming the thermal inertia of the plant - during the heating up and cooling down phases of operation, which makes the cost per kWhr of electricity produced higher than the figurative $1.50/kWhr. This is what the Labor Party and Greens do not understand about the economics of running a coal fired power plant, and the effect that increasing renewables has on overall power production costs.