Category Archives: Energy

Wind keeping the system “nicely balanced”: does more wind power means better air and cleaner electricity?

Let’s continue with the open letter from the energy company Eneco (see previous post), in which its CEO complains that his company “felt obliged” to shut down some of their windmills despite it was windy. It is framed as the result of the “inflexibility” of nuclear power that pushes wind aside and, most importantly for this post, as a choice for better air and cleaner electricity (translated from Dutch, my emphasis):

Renewable energy could provide half of our consumption. In itself this is a good prospect: better air and cleaner electricity from wind & sun. We should all be pleased with that.

The framing in the open letter made me wonder how much wind power was curtailed exactly? Also, assuming that nuclear power would get turned down a notch during the lockdown, how much cleaner would electricity production then get?

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Wind keeping the system “nicely balanced”: wind, meet nuclear

Never could imagine that the words “wind energy” and “nicely balanced” would be used in the same sentence. This was achieved in this tweet (for the international readers, “BE” is the country code for Belgium):

BE update: Wind offshore dropped as of 10am, onshore as of 11am. And it is keeping the system nicely balanced. But of course, if only we could have dynamic demand response to this, society wouldn’t have to loose this cheap energy.

This are the graphs that accompanies the tweet:

Tweet dieterjong 20200421

There was indeed a sudden loss of wind capacity somewhat before noon, correlating with a negative price and leading to positive prices again. Initially, I assumed that the twitterer was being sarcastic, mocking a sudden wind lull, but scanning through his Twitter time line suggested that this might not be the case…

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Hornsdale Power Reserve: huffing and puffing old men coming to the aid of their colleague

Now it was established in previous two posts that the Hornsdale Power Reserve did surprisingly little to avert a frequency drop caused by a 560 MW capacity loss (contrary to what was suggested in the RenewEconomy article), the focus of this post will be on how the message was brought. Knowing how little the battery actually did, then how on earth could Giles Parkinson paint it as if something extraordinary had happened? This post will explain how this is done.

Let’s start with the title:

Tesla big battery outsmarts lumbering coal units after Loy Yang trips

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Hornsdale Power Reserve: the mouse that stopped the elephant from falling

After writing previous post, the RenewEconomy article kept going through my mind. The author of the article suggested that the response of the Hornsdale Power Reserve to a tripping coal fired power unit was extraordinary, when in reality it was insignificant in the grand scheme of things. I wondered why on earth the author was so lyrical about what was in fact a poor performance…

Then it suddenly struck me. It might well be a misinterpretation of how the event was represented.

Let me explain.

There were two graphs presented in the article. The first one is the frequency versus the response of the Hornsdale Power Unit and it stood central in previous post. There is however a second graph in the article and it is this graph that could easily lend itself to misinterpretation. It shows the sharp decline of the tripped coal unit combined with the response of the Hornsdale battery:

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Hornsdale Power Reserve: “outsmarting” lumbering coal units by four seconds?

This is an update on a previous post about the claim that the Hornsdale Power Reserve (in South Australia) is helping to prevent blackouts in Melbourne (in Victoria), roughly 1,000 km away from each other. In that post, I rejected that idea, saying that this was highly unlikely because the capacity of the Hornsdale battery is way too small to do so.

In the meanwhile, I got a link to an article that seems to describe such an event. At the end of 2017, just after the Hornsdale Power Reserve was put into use, a coal fired power plant unit in the state of Victoria tripped, causing a sharp drop in frequency and that triggered the Hornsdale battery to supply power to the grid. Its response was much quicker than that of a coal fired power plant commissioned to compensate for the loss.

Melbourne was not specifically named in the article, but the question doesn’t really change much: did the Hornsdale Power Reserve in South Australia actually helps to prevent a blackout in the neighboring state of Victoria after a coal fired plant unit failed there in December 2017?

Did this article really provide some solid evidence that this happened? And if so, how did the battery manage to do so, considering its capacity is only 100 MW and can store 129 MWh?

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Hornsdale Power Reserve: calculating oneself rich

In Flanders, we have the expression “calculating yourself rich”. It means presenting one’s case in a too optimistic way that doesn’t accord with reality. This can for example be done by only counting the positives or by making overly optimistic assumptions. Both can result in an end result that is far too optimistic. Therefor “calculate” yourself rich instead of “being” rich. It is not real wealth, it is fully dependent on the tricks used in the calculation.

This expression popped up in my mind when I read an article about the blessings of grid sized battery storage (see previous post). To recap: two advocates for solar and wind claimed that batteries could replace natural gas power plants for peaking and gap-filling. Reading the linked article, it became clear that it had nothing to do with the claims made by the two advocates. The subject of the linked article described how the Hornsdale Power Reserve earned money by providing FCAS services to the South Australia grid.

This is how the article starts:

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Hornsdale Power Reserve: helping to prevent blackouts in … Melbourne?

After writing previous post, I wondered how much impact the Tesla battery of the Hornsdale Power Reserve actually has on the South Australia grid. Just looking at the numbers (the battery has a capacity of 100 MW and can deliver 129 MWh), I expected it to be rather insignificant. In the meanwhile, I came across a heated discussion on a reblog of previous post on the blog “Utopia, you are standing in it!“. That post was about the Tesla battery of the Hornsdale Power Reserve in South Australia. The discussion started with the comment that South Australia is a net exporter and after the question how long the Tesla battery would last, this suprising claim was made:

Long enough to stop potential blackouts in Melbourne because of the unreliability of their coal fired power stations! […]

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Hornsdale Power Reserve: batteries compensating for intermittency?

It has been a while since last post (on the Doctor’s analogy skeptic style). This post will be a bit different. It will be about energy, more specifically about (grid sized) energy storage. It all started with this tweet from Jean-Pascal van Ypersele. This is the text of the tweet:

Those who argue that fossil gas plants are needed to compensate the intermittency of renewable energy should read this @McMarghem @eliacorporate @EngieBelgium @LuminusEnergie @Gregoiredallema

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A simple model: seasonal storage in perspective

In previous posts, I threw around a bunch of numbers and sometimes mentioned that these are insanely high, but never gave an idea how high. I now will try to put them in perspective in this post. I found a sweet spot where solar and wind both could deliver enough power to meet demand. This happened at 8.57 times the current capacity of solar and wind, supported by seasonal storage of 2,421 GWh. I called that an insane amount of storage. How would this compare to actual demand over the year?

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A simple model: an optimal mix of solar and wind?

When comparing seasonal characteristics of solar and wind in previous post, there was one graph that got my attention:

simple energy model (charts007d) - belgium - solar x10 and wind x19.05 - reference year: 2018 - with_unlimited_storage

It shows wind got shortages (visible orange lines) during the summer months, while solar had its best production at the same time. Solar got shortages in the beginning and end of the year, while wind had a decent production at the same time. Then it is tempting to assume that solar and wind are complementary. I understand that solar and wind are only complementary on average. When it comes to individual timeslots, they are certainly not complementary. That is an disadvantage when production and demand need to be in balance at all times.

What if we throw in storage? Is there an optimal mix of solar and wind that can deliver as much as possible direct power from solar and wind, therefor minimizing storage requirements? Separately, both solar and wind have dizzying storage requirements. Yet they could be balanced by means of 2,421 GWh storage in my first post on storage. This tells me that quite some gain is possible combining them both. Can we go even lower by varying both capacities? Maybe even in a storage range that is feasible? However, at a higher multiplier both drifted apart and solar was left far behind, so it might not be as simple as it looks.

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