By Bob Irvine
Cheap intermittent renewables appear to be very expensive.
The current Australian Government has ruled out nuclear energy and is committed to phasing out all fossil fuel base load power with gas seen as a transition fuel to an energy grid run entirely by intermittent wind/solar with battery or pumped hydro storage, with a small contribution from direct hydroelectric base load.
Can any of the electrical engineers at this site estimate the cost to consumers of a system run in this way. Is such a system even possible?
I live in Queensland, Australia. Until 30/6/23 our power bill for general usage was 25.559 Aus cents per kwh. On the 1/7/23 it jumped to 31.724 Aus cents per kwh a rise of about 24%. This is up from about 19 cents per kwh a few years ago.
The long-term picture is not much better. The Australian power price history has a close correlation with the penetration of intermittent generation into the system. See Figure 1, below.
Figure 1, Australian Energy prices compared to intermittent wind/solar penetration into the grid.
The Australian Energy market Operator (AEMO) has been singing the praises of “low cost” wind/solar for many years now.
To counter these assertions, I decided to collate the daily wind energy input to the Main Australian Grid, referred to here as simply the “grid”. This Main Australian Grid has an enormous area but does not include the Western Australian grid which is separate and about 8% of the size of the main grid.
My data source is this great site compiled over many years by Anton Lang. Thanks Anton.
I will focus mainly on wind intermittence here with a short paragraph on solar intermittence at the end. The figures and graphs quoted here refer to the entire grid and indicate that the wind is not always blowing somewhere as claimed. It is almost certain that at various times there will be no wind energy generated at all over large areas of the Australian continent.
Apologists and propagandists for intermittent wind usually quote monthly penetration as this has less variability. It is, after all, averaged over longer periods. A truer picture is attained by looking at daily wind penetration and comparing that with the variation within each day.
This has been done in Figures 2 and 3 below.
If we look at daily averages, wind contributed 5% or less of total grid generation on 9 days for the 285 days covered. See Figure 2.
It is only when we look at the variation within each day, however, that the true picture emerges. For the year from 26/9/21 to 25/9/22 wind contribution dropped below or was equal to 5% of grid generation at some time during the day on 151 days. It dropped below 2% at some time during the day on 32 days and dropped below 5% at some time during the day on 18 of 20 consecutive days from 10/3/22 to 29/3/22.
All batteries and pumped hydro storage would have been exhausted during this period unless a massive overbuild is being proposed. If we were to cover the entire grid, my back of the envelope calculation is that we would need tens of thousands of industrial scale batteries to provide reliable power during this period of low wind activity. The capital cost alone would be two to three times Australia’s GDP. Even with some hydro and gas in the system it would appear that a system of this type is almost impossible to imagine.
As mentioned, these figures are averages for the entire grid. If we were to look more locally it is virtually certain that there would be no wind generated energy into the grid at all for large areas of the east coast for hours at a time and at times very little over many days. In this situation, of course, we would need tens of thousands of kilometres of high voltage power lines to keep the lights on over the entire country.
Add to this the tens of thousands of square kilometres of wind farms and we have fundamentally changed the Australian landscape. A real environmental catastrophe on a massive scale and all our own work.
The graphs below show the difference between looking at intermittence as daily averages and alternatively as 5-minute averages within each day. The system has to cope with enormous changes of wind input over short time scales and certainly on the scale of hours. Australia is an island and can’t import energy from neighbouring countries, so I can’t see our energy system coping with this variability when we have decommissioned all our base load power. This impossible situation is the stated aim of our current government unless you believe green hydrogen can play the base load role and be brought on-line very quickly. It can’t and it won’t be.
Figure 2, Over the 9.5-month period covered, wind provided 5% or less of the total grid generation on 9 days and 10% or less on 102 days out of a total of 285 days.
Figure 3, At some point during 151 days in the year shown, wind input to the grid was less than or equal to 5% of the total energy generated by the grid. This low input often lasted many hours and was 2% or less at some time on 32 of those days.
Wind input to the whole grid is graphed for 19 typical days in the appendix below. While we have significant coal base load power in the system we can deal with this intermittence. Nearly all Australia’s base load coal power stations are slated to be gone by 2030. At that point the instability in the system would be unsustainable and catastrophic. Remember gas is only mentioned as transition base load by our current government and is expected to be phased out over time.
The average solar input to the grid for the month of June 2022 was 1742 MW and for December 2022 was 4015 MW. These figures indicate that solar input in winter is approximately 43% of summer input.
Solar input also goes to zero every day at night fall. It’s possible our Government may have noticed this already.
SOME BASIC FACTS
- Wind generated about on average 11.3% of total grid generation for the year to 21/6/23.
- Wind Capacity Factor (CF) for the 4 years prior to 22/9/22 was 30.38%.
- Wind CF for one year to 22/9/22 was 30.40%.
- Industrial solar CF is 18 to 22%
- Rooftop solar CF is 12 to 15%
- Solar contributed about 15% of total grid generation in 2023.
- Hydro contributes about 8% of total grid generation.
APPENDIX – SOME TYPICAL DAILY WIND VARIATION FOR THE ENTIRE GRID