Monthly Archives: September 2020

When solar and wind capacity increase

When pointing to the huge fluctuations of solar and wind production in previous post, I wrote that these fluctuations will only grow when South Australia advances on its path towards 100% renewable energy. Looking at the fuel mix and demand data that I had gathered until then, I noticed a fine example of exactly that. Just look at the fuel mix and demand data:

AEMO South Australia (charts0011a) overview

Let’s focus on the minimum on September 5 at 20:00. That is around the time that I looked for the first time at the overview panel (see previous post). The data showed that the total production of solar and wind was 4.341 MWh, which is 0.29% of what was produced at that moment. Contrast this to the peak of 1,258.486 MW the next day around 22:00, just after the evening peak when energy demand was slowly starting to decrease. It is this dynamics that will lead to the fluctuations that I wrote about.

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Hornsdale Power Reserve: the share of battery power in South Australia

The Hornsdale Power Reserve is about to get an upgrade. The Hornsdale Power Reserve is a grid-sized battery build by Tesla in South Australia. It has a capacity of 100 MW and can deliver 129 MWh. I did a series on it back in March, starting with the claim that this battery could replace natural gas for peaking and gap-filling (which is not the case). The upgrade will add a capacity of 50 MW and it can deliver 64.5 MWh.

The pv-magazine article points out that the additional capacity will be put to use for frequency control and inertia. I could understand that, the main function of the original 100 MW battery is already frequency control and this service generated quite some money for its owner. There was also this claim (my emphasis):

ARENA, which contributed an AU$8 million grant toward the expansion, also believes the upgraded battery could also help to reduce renewable curtailment in South Australia. Indeed, AEMO’s Chief System Design and Engineering Officer, Alex Wonhas, said that the expansion enabled the “optimal use of this world leading battery to support higher levels of renewable integration.”

The author also didn’t shy away from using terms like “mega” and “highly successful” in the article. That all sounds very promising, but from looking into the Hornsdale Power Reserve while writing the earlier series, I think it is presented way nicer than it actually is. Even a “mega”-battery of 100 MW / 129 MWh is still tiny grid-wise and adding another 50 MW / 64.5 MWh will probably not make much of a difference.

This made me wonder: what is the current share of battery power in the South Australia grid? And what difference would this upgrade make once it gets online (the homepage of the Hornsdale website states that the expansion is still “under construction”)?

Time to look at the data.

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