JoNova

By Jo Nova

Don’t mention that capacity factor…

The media and wind industry always sells the biggest, best new generators at their full imaginary capacity. The newest largest wind farms are said to be “1 GW”, even though they will almost never supply that. The real percentage they supply of the advertised “capacity” is called the “capacity factor” and it rarely gets a mention.  The average reader, not paying attention, won’t notice that the $2b cost doesn’t stack up at all. It’s like buying a brand-new car without knowing it only gets 7 miles per gallon (and only when the wind blows).

We need to know ‘the mileage’

The latest GenCost report uses the term “capacity factor” literally 100 times (I counted), so obviously it’s central in calculating the value of a generator, yet it is that which shall-not-be-named in public discussions. And when they do say it, it’s often worse than they say, and that bad number is also shrinking.

In 2019 the CSIRO Blob Experts bravely assumed that the modeled average capacity factor of onshore wind would be 44.4%. Years later, in the latest GenCOST report they assume, like an addict, that it would between 29% “and 48%” — still fantasizing that a miracle is about to come. So their modeled prediction of the cost of onshore wind power is ridiculously generous. Even after reality doggedly stayed around 30% for six years, a google search shows the NSW government “fact sheet” says it’s around 35%  and the Google AI overview says it’s 30% “to 45%“.

How imaginary homes are powered by imaginary capacity factors

Anton Lang, also known as TonyfromOz is yet another volunteer creating the graphs that the CSIRO, AEMO, ARENA, ABC, and AER get billions of dollars to provide, but don’t want us to see. For years Tony noticed that the paperwork advertising wind “farms” didn’t mention the capacity factor.  It seemed like a strange gap in the documentation. Tony noticed they usually converted their output to the fantasy fairy-thousand-homes it would supply which is a pure marketing ploy. They pretend, deceptively, that wind turbines are capable of powering any homes at all. When Tony back-converted the number of homes, he realized all the companies marketing wind turbines were assuming a capacity factor of 38% to create the imaginary homes value.

So he used his collected data to calculate the capacity factor of all Australian wind plants, and discovered, that averaged over the last seven years, it is just under 30%. It started out at about 31% in 2019 but has declined, and over the last year, the rolling 12 month weekly average capacity factor has often been close to 27%.

Thanks to Angus McFarlane for the graph where we can see the slide in wind turbine capacity:

During this time the total nameplate capacity grew from 5.3GW to 13.5GW. Despite improvements in design, and the young age of this fleet, the capacity factor is getting slightly worse, not better.

As Angus McFarlane points out GenCost uses the highest possible capacity factor on the upside, but calculates the “low option” a different way to hide how low it really is:

GenCost uses a low value for capacity factor that is “10% below the average”. This is contrary to normal engineering practice, which would be to use the 5^th percentile for the low value. For example, IRENA use 5^th percentiles for low values of capacity factor. Furthermore, using the 5^th percentile for Australian wind would result in a low capacity factor of 19.5%, which might explain CSIRO’s aversion to using it.

If only we had a scientific institution paid by taxpayers that gave unbiased scientific advice, eh?!

Three reasons the weekly capacity factor is headed downwards

• One: the best sites for wind plants are already taken. All the windiest spots near transmission towers with spare space are built on. Thus new wind installations either have less wind, or are further from population centers.
• Two: no matter how many new turbines are installed, the high pressure cells still cover the whole country, and thus the extra generation comes mostly when we don’t need it. More turbines, means more curtailment. More solar means more curtailment at lunchtime.
• Three:  The equipment is always degrading. High wind zones are tough places to put any infrastructure. The wind, flying sand, dust, ice and salt are continuously degrading the trailing edges of the blades which increases turbulence and reduces efficiency. And the stop-start nature of wind is awful on gears and bearings. The blades are so heavy that even when the wind doesn’t blow, the rotor has to turn slowly, or the bearings will flatten.

Why the lowest of the low points matter

The figures in the graph above are weekly average values, but what also matters are the capacity factor on the worst days, and the worst half hour, because that tells us how much back up power we have to have. In those moments the capacity factor of a whole country full of wind turbines can be as low as 0.7%. On a bad day $20 billion dollars of wind power across Australia can only guarantee as much power as two diesel generators.

How much back-up do we need for a 13.5 gigawatt wind system? The awful truth is, about 13.4 gigawatts. The entire wind industry is effectively a superfluous add on to a full reliable grid. It’s main productive benefit (allegedly) is the hope of changing storms and floods in 100 years. It can not possibly be cheaper than our current system unless fuel costs were the largest share of electricity costs, which they aren’t.

Those high pressure cells just won’t go away:

Look at how big these horrible high-pressure cells are which stop the wind across the whole continent. Make them stop!

Depressingly, Paul Miskelly did the calculations back in 2012 and the capacity factors were around 31% even then. The AEMO, CSIRO, and AER have known all along, surely, that it wasn’t 35%, 40% or 48%. They were either living off false hope or doing false advertising. 

It’s time the Australian people knew.

REFERENCES

Paul Miskelly, (2012) Wind Farms in Eastern Australia-Recent Lessons, Energy & Environment 23(8):1233-1260, DOI:10.1260/0958-305X.23.8.1233

Anton Lang publishes his work at PaPundits. 

—  More coming soon from Angus McFarlane on the exaggerations and fantasies of CSIRO’s GenCost. —