I put these two charts together because I was curious about the divergence of combined max and min output for coal-fired power in QLD and NSW. Is the maximum going up or down? Is the minimum going up or down? How can it be presented nicely (most important part :P).
For context, NSW is Australia’s most populous state with the highest electricity demand peaking around 14 GW in summer. QLD is next peaking around 11 GW.
The daily VWAP for each region helps to identify significant events, such as carbon tax, very hot days, the introduction of upstream LNG demand in QLD, COVID lockdown price suppression, 2022 crisis and the general increase in price volatility with the growth of renewables.
The strong orange and blue lines are a simple Excel moving average of the underlying noisy data, itself the maximum and minimum combined daily MW output of coal-fired power stations in each region. Yellow is the difference.
I’m strongly of the opinion that the minimum demand problem will prematurely close many coal units before pressure from cost or age. We now see minimum coal breaching 2,500 MW in QLD and 1,500 in NSW. With the minimum turndown of a coal unit around 40% MCR, the result is inevitable. QLD has over 8,000 MW of coal units, and 40% is around 3,000 MW.
In the QLD data presented here there are 34 days when the daily minimum coal output breached 3,000 MW, and 30 of those occurred in 2024/25.
Note this is a technical problem, because the physics always trumps the economics. Solutions include building more flexible generation i.e. gas. Some will say batteries, and there’s definitely a business model for batteries at least for the time being.
Solutions also include more load. Batteries are ‘sometimes’ load just as they are ‘sometimes’ supply. Datacenters seem unlikely to me because of the power cost and small population in Australia. Hydrogen electrolysers - nope.
Aluminium? Also unlikely, refer to costs for everything.
But Australia does have a lot of gas. Maybe one day we’ll have the will to use it…
Below - AEMO has some pretty outrageous assumptions!
