Nuclear undercutting wind?

This is already the third post in the series on the tweets of the Belgian Minister of Energy about offshore windmills that were temporary shut down on July 29. The first post was about the “low pricing”, that were in fact day-ahead prices and nothing to cheer about. The second post dug deeper in the statement that Belgium benefited from the import from Germany’s surplus electricity from solar and wind. Yet, when Germany had high production of electricity from solar and wind that day, Belgium had a high production too and it was primarily exporting its own surplus, so there was no import from Germany to benefit from at that moment…

The subject of this post will be the inflexible power source that, according to the Minister, was the root cause of this curtailment. The first tweet didn’t name the culprit, it was in the fourth tweet that she used the n-word (nuclear):

There you have it, today a practical example that shows how our energy system must change and that nuclear energy stands in the way. They simply undercut sustainable CO2-free production. 4/5

There were several charts added to the first tweet to support her claims, however there was no chart illustrating the claim that “nuclear is in the way” (although it would have been pretty simple to do, just show a quasi straight line for nuclear while having a nose dive for wind). If she would have looked at what nuclear did on July 29, this is what she would have seen:

Not only offshore windmills decreased their production, also nuclear power plants did so. Except for the first 1 hour 45 minutes, nuclear decreased its production roughly as much as wind did (curtailing ± 500 MW of its capacity).

The surprise doesn’t stop there. Look at what natural gas did:

That is a pretty contra intuitive move. Natural gas is the more flexible of the two, yet this time it increased its production by almost 500 MW between 8 AM and 3 PM… Weird that natural gas didn’t lower its production as one would expect it to do. It now went from around 750 to almost 1250 and back, while it could even go below 750 (it had lower production before, so 750 MW is definitely not its minimum capacity).

This time it was nuclear that budged and gas did the exact opposite. The 500 MW extra of natural gas basically nullified what nuclear had cut down between 11 AM and 3 PM.

Don’t understand me wrong, I have no doubt whatsoever that gas fired power plants are way more flexible than nuclear power plants, but whether this specific case was an example of nuclear “standing in the way” is less clear cut. What this case shows is that 1) nuclear power can modulate, albeit limited relative to its capacity and 2) natural gas was less flexible than expected (even opposing the efforts of nuclear and wind).

That explains why the Minister didn’t illustrate the response of nuclear, because this would diminish her argument. She couldn’t show the response of natural gas either because it would be inconvenient (she proposes natural gas as the solution for the intermittency of solar and wind, so the Belgian nuclear power fleet could be retired).

What about the claim that nuclear simply undercuts sustainable CO₂ production? Our Minister of Energy was very careful in her wording. She referred specifically to wind and its curtailment during July 29. In this specific case of overproduction combined with low demand, wind was prevented producing (emission free) electricity because of negative prices caused by surplus electricity of inflexible nuclear. Therefor reaffirming that nuclear power should better be ousted to give way for wind and storage.

Note what she didn’t say: she avoided claiming that decommissioning nuclear would drive emissions down. Even if nuclear power would be decommissioned completely and therefor would not “stand in the way” of wind anymore, this will not lower emissions. On the contrary, her policy is to replace (emission free) nuclear power plants by (not emission free) gas fired power plants and relying more on import (which might be problematic in stress situations, see previous post). Sure, when nuclear is displaced by the more flexible natural gas, nuclear will not stand in the way of wind anymore, but it will result in increasing emissions.

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