Purpose: To signal the critical situation for power security and the implication of the lowest “choke point” level of input from the sun and wind.

The Critical Issues:

(1) After the loss of several coal fired power stations  we have virtually no spare baseload capacity. We are “running on the rims” with no spare tyre.

(2) Many times a year when the wind supply is critically low the system will “choke” unless  conventional power sources (dominated by coal) can provide 100% of the demand for electricity.

(3) That situation is rare at present but it will be a constant danger when Liddell closes in 2023 taking almost 2GW of supply out of the system.

(4) We are told that wind and solar power can replace  coal-fired power stations as they go out of service.  Due to the choke point problem that will not work because RE can displace coal but cannot replace it, as explained in note 21.07. 

Key features of the situation. (Briefing Paper follows)


That all politicians be advised of the critical threat posed by the choke points.

That pundits on TV, radio and print media be advised and provided with supporting information so they can pass the message to the public.

That news and weather reports include the % of demand for power being supplied by wind at the time.

Choke Point Briefing Paper

Purpose. To provide supporting information and speech dot points to explain the choke point problem.

We have an unprecedented situation in SE Australia with virtually no spare capacity to handle peak demands when they coincide with “choke points” at he minimum level of supply on nights with little or no wind.

“Choke point” conveys the urgency of the situation like the time when a person is choking or drowning and the lungs are starved of air. .

If the grid depends on sun and wind power then parts of it will die on nights when there is little or no wind. 

That situation occurred in January last year (2019) when some coal-fired capacity was off line in NSW and the lights had to be turned off in parts of Melbourne. The Victorian Minister for Energy blamed the deficiencies of coal power stations but it really demonstrated that they are indispensable.

We know the sun is off duty at night and we know from the records that the wind supply drops very low many times every month.  

Key features of the situation.

No spare capacity. With the loss of several coal fired power stations in recent years there is no spare capacity in the system. This has been signalled by the Australian Energy Market Operator (AEMO).

Liddell coal fired power station in NSW is scheduled to close in 2023 taking 1.8GW out of the system.

Without additional power to replace Liddell many lights will go out at times of high demand on summer evenings and probably winter evenings as well (see Victoria in January 2019).

This chart shows the situation at 6.30pm EST (5.30 Qld) on Wed 29 January, a normal weekday evening for that time of year.  SOURCE https://anero.id/energy/


Coal (black and brown) provided 20GW to account for two thirds of the demand.

Natural gas (purple)  and Hydro (blue)  each contributed about 3GW. 10% each.

The RE components are Wind (green)  1.7GW, 5.7%

Field Solar (red) 0.8, 2.7%

Rooftop solar (yellow) 1.4, 4.7%

Solar is fading rapidly at that time of day.  

Conclusion. In the foreseeable future there is no way that wind power can replace coal fired power.   Any loss of coal-fired capacity will become critical unless some other cost-effective and reliable substitute can be found before 2023.

Recommendation.  That the problem of the choke point in wind power be explained to politicians and the wider general public so it becomes a topic of serious discussion in political party rooms, across the media, and wherever people get together and talk about current affairs.