Tag Archives: Solar energy

Electricity price briefly below zero thanks to sun and wind!?

There was a high production of electricity from solar and wind previous weekend (weekend of April 23-24). As expected, there was the usual cheering and celebrating of this event. One of the many was this tweet from a member of the Flemish Green party (translated from Dutch)

Still need arguments for the roll-out of renewable energy?

Electricity price briefly below zero thanks to sun and wind

Tweet WouterDeVriendt 2022-04-25

He links to a newspaper article with the same title and brings forward these negative prices as a decisive argument for more solar and wind: if you weren’t convinced yet, then this surely is the argument that will.

I don’t really agree with that. Those negative prices over the previous weekend are not an argument for the roll-out of solar and wind (maybe even the contrary) and it shows his poor understanding of why exactly electricity prices dipped below zero in that weekend.

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What when the sun doesn’t shine and the the wind doesn’t blow: batteries!?

The big question was asked again. Remember, a few posts ago, our Minister of Energy tried to answer the question “What happens when the wind doesn’t blow?”, a question she apparently got asked a lot. Back then she managed to evade answering that question.

The question came back in an interview (Dutch ahead) about the energy transitions she gave to a news magazine from Brussels. Initially, it seemed we would not get an answer (the interview was interrupted at the exact moment when the question was asked), but fortunately the reporter was persistent enough to ask the question again later in the interview (translated from Dutch, my emphasis):

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Wind from Denmark to the rescue?

One of the solutions that our Minister of Energy proposes for the energy transition is interconnectivity. In the webinar she gave at the end of 2020 (see previous post) she was pleased that Belgium got connected to the German grid and therefor could start to take advantage of the electricity produced by solar and wind in Germany. I am less optimistic about that. As I found in some previous posts like for example here, here and here, Belgium and Germany are neighbor countries and therefor have similar patterns of solar and wind production.

That doesn’t necessarily mean that no gains could be made by this interconnection. There will be times when Belgium could use the solar/wind overproduction of Germany, but when Germany has a excellent intermittent production, then generally Belgium does too. The same when Germany has only little intermittent production, then Belgium generally experience the same. The more intermittent capacity build in the two countries, the less Belgium will be able to take advantage of excess electricity production from intermittent energy sources.

This is however not the only interconnection that our Minister of Energy wants. A year after the webinar, she signed a memorandum of understanding (Dutch ahead) with Denmark to look into the possibility of a submarine power cable connecting Denmark with Belgium. That made me wonder whether this submarine cable would make it possible for Belgium to take advantage of Denmark’s excess intermittent electricity production and that is what I will look into this post.

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Claim: 1 GW solar and wind equals 1 large nuclear power plant

Our Minister of Energy keeps on making unthinking claims. In a post a couple weeks ago, I wrote about the “2 GW only represents 2% of our energy supply” claim that she made in an attempt to minimize the effort needed to replace nuclear by solar and wind, apparently not realizing that the share of solar plus wind is not that much better when using the same standard. Recently she made the claim that our government will realize 1 GW of renewable energy every year in the coming years and that this equals 1 large nuclear power plant per year (I think she means nuclear power “reactor”).

She made that claim after the decision was announced that Belgium will keep its two youngest nuclear reactors open for another decade (the illusive “plan B”). The Minister went to that meeting with the proposal to close all nuclear plants and a comprehensive plan to promote solar and wind amounting to 8 billion euro. The final decision was to keep open the two youngest reactors and only 1 billion euro of that 8 billion was approved, so she obviously had to accept some losses. It is in that context that the claim was made in the radio program “De Ochtend” (“The Morning”) after the reporter put forward that this result is not something to be proud of. The Minister objected to that view and doubled down by framing the result of the negotiations as some kind of victory (translated from Dutch, my emphasis):

Gosh, do you know with what I am coming home with? I am coming home with 1 GW of energy that we will realize every year in the coming years. For comparison, 1 GW is 1 large nuclear power plant.

That is not a one-off, she said something similar at the end of the interview (translated from Dutch, my emphasis):

One of the most important things on the top of my list is, and that’s going to sound really boring: defense and aviation. They have radar systems, they have areas that are not accessible to wind turbines where we can realize 1.5 GW of renewable energy. That is more than a large nuclear power plant with a one-time investment.

This comparison with nuclear seems to suggest that Belgium would replace a 1 GW nuclear power reactor per year, but this obviously can’t be what she is claiming because in that case Belgium’s huge electricity problems would be painlessly solved in just a few years. Therefor I assume that she means that she just wants to add a capacity of 1 GW of solar and wind per year. However, these two don’t compare that well. The impact of 1 GW of solar and wind capacity will be much less than 1 GW of nuclear power, so it might be much less impressive than she is suggesting. How much less? Well, let’s just make that comparison.

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Comparing solar and wind in the Netherlands with Belgium

In the post at the end of February, I compared two graphs showing the electricity production by solar and wind versus household electricity demand of the Netherlands, this for the months of June 2021 and December 2021. Belgium is a neighbor country of the Netherlands, so I wondered how electricity production by solar and wind in Belgium would compare with the Netherlands in the same period.

Both countries have around the same share of solar and wind in electricity demand, but population is different (more people in the Netherlands) and also have different installed capacities of solar and wind (much more solar capacity in the Netherlands), so that could show some interesting differences.

The Belgian solar and wind data is registered at 15 minutes intervals, but I don’ t think that this is the case for the graphs of the Netherlands. My guess is that it uses 1 hour intervals (quarter hour intervals or half hour intervals would give much more fluctuations). Combining the data of Belgium at 1 hour intervals with the digitized data from the Netherlands gives this:

Chart16b: solar and wind, Belgium vs the Netherlands

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Pot, meet kettle: 2 GW represents only 2 percent of our energy supply

Turns out that our Minister of Energy last week made the claim that “2 GW represents 2% of our energy supply”. That doesn’t make much sense. Initially, I couldn’t find where exactly she said that. There was a lot of chatter about it on social media, but it was not clear what she said exactly and in what context. Luckily, I found this tweet on her Twitter time line (translated from Dutch):

Government will decide on the basis of affordability and security of supply and I will add a third criterion: energy independence.

2 GW represents 2% of our energy supply. We need an agreement for 100% of our energy supply.
#deochtend

Tweet TinneVdS 20220328

The tag #deochtend in that tweet refers to the radio program “De Ochtend” (“The Morning”) and yes, on February 28 there was an interview in that program with our Energy Minister about the situation in Ukraine and its consequences on our energy prices (from 02:13:48 until 02:24:40, the 2% claim is made at 02:22:24). The context of this claim is the Belgian nuclear exit. There are currently two options:

  1. Decommissioning all seven Belgian nuclear power plants (plan A)
  2. Decommissioning the five oldest and only keeping the two youngest running (plan B).

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A “skewed” distribution: the overlooked consequence of decommissioning nuclear power

In previous post, I detailed the contradiction of Belgium wanting to profit from German cheap import while employing the exact same balancing strategy as Germany. I illustrated this by comparing German electricity export and prices on days of the lowest, highest and median output of solar and wind. This showed that when Germany exports its excess electricity, prices are generally low, but at that time Belgium is also busy exporting its excess electricity. And vice versa.

Now you could object that this is not a good representation of the argument of our Green Minister of Energy. Her argument is that nuclear power stands in the way because it can’t modulate its output (enough) to follow the intermittency of solar and wind, sometimes leading to wind power being curtailed and/or exported at times when Germany is exporting abundant and cheap electricity. The goal of the Minister is to get rid of nuclear power generation so Belgium doesn’t need to curtail its own production when it is sunny and windy, while also being ready to profit from cheap electricity from Germany. Ka-ching!

That is true, decommissioning nuclear will allow for more cheap import from Germany, but this will only be temporary and lead to an even bigger problem…

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A “skewed” distribution: interconnecting intermittency

While creating the graph that I used in previous post, I noticed something that I expected for a long time. Remember, my graph was a recreation of this graph showing the sorted daily contribution of solar and wind in the Netherlands:

Sorted contribution of solar and wind of the Netherlands

It shows that the lowest daily production of solar and wind between January 1 and November 16 was measured on November 16. When I was creating my graph depicting the Belgian sorted daily contribution, I found that the lowest production of solar and wind in Belgium over the same period was also November 16. That should not have come as a surprise, Belgium and the Netherlands are neighboring countries.

That November 16 date was not the only date that appeared in that original graph. Besides November 16 (lowest production) there are also July 29 (highest production) and August 2 (in between). That made me wonder whether those two other days match as well and to what extent this is also true in other neighboring countries. I have some data from solar and wind in Germany, so I will also include Germany into this comparison. Let’s dive right in.

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A “skewed” distribution: the volatility of solar and wind

This tweet sums up the biggest problem with intermittent power sources:

Yesterday, a fairly dramatic low in terms of solar & wind output. Fortunately, there were also great days this year.
Although sun and wind often complement each other, the total forms a rather ‘skewed’ distribution. We will have to learn to deal with that soon.
#graphoftheday

Tweet WM_visser 2021-11-17

This is the graph he is talking about:

Sorted contribution of solar wind (The Netherlands)

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Pumped hydro more expensive than batteries: why the winner is unclear

Previous post ended with the conclusion of Brakels’ article that the “winner is unclear”. That is quite a surprising conclusion of an article praising the strengths of the batteries while downplaying the weaknesses. These are the two reasons why Brakels thinks that the winner is unclear (my emphasis):

But because Snowy Hydro 2 may come in at less than the $10 billion or so I expect and because I can’t be certain the additional return from the battery setup will be enough to replace them when they fail, I can’t pick a winner.

The second argument is the most interesting. That statement looks rather cryptic and the meaning depends on the definition of the words “return” and “fail”.

“Return” could mean financial return and “fail” could mean end of economical life (additional financial return of the battery/solar scenario is not enough to replace the installation after its economical life). I will explore this meaning in the following post.

“Return” could also just mean output and “fail” could mean when the additional output of the battery/solar scenario is insufficient (additional output of the setup is not enough to fill in demand and then there would nothing to replace it with). If that is what he means, then he is rightfully pointing to the fatal flaw in his calculation:

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