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.

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 plant 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.

Nuclear and solar & wind are two different beasts. Nuclear power reactors generally operate at or near their rated generating capacity throughout the year and have relatively high annual capacity factors. They generally only interrupt that production pattern for reloading (every 1 to 2 years, during times of low demand) or for maintenance or for repair. This is contrary to solar and wind that depend on the presence of the sun and wind. Solar and wind power only perform at maximum capacity in optimal conditions. For solar that is at a perfect location around noon on a sunny day. For wind in a windy location with enough, but not too much, wind.

Okay, how does 1 GW of solar and wind power compare to 1 GW of nuclear power? In a couple previous posts, I used a dataset comparing solar and wind production in the months of June and December 2021. I will use that data to compare nuclear power (able to operate near or at their rated capacity of 1 GW) and solar/wind power (operation limited by the weather of the moment, so 1 GW produces (much) less than its theoretical peak performance).

This is what 1 GW of solar would produce in the period June and December 2021:

Chart16c: solar per 1 GW capacity (Belgium)

As expected, solar performs very poorly in winter (less than 2% of its maximum capacity). It does way better in summer, but even then it is still less than 20%.

This is what 1 GW of onshore wind would produce in the same period:

Chart16c: onshore wind per 1 GW capacity (Belgium)

That is a tad better than solar and best production is in the winter period. But that is still only 7% in June and 22% in December.

This is what 1 GW of offshore wind would produce:

Chart16c: offshore wind per 1 GW capacity (Belgium)

That is way better, definitely the best of the three. It is producing most in a period when demand is highest (good), but that is not a given (not so good). Just look at the middle of December, roughly from December 11 until December 21, when (onshore as well as offshore) wind production basically collapsed. Solar was pretty insignificant anyway in the same period.

If I compare them according to their current capacity share, then 1 GW of solar and (onshore and offshore) wind combined would produce this:

Chart16c: intermittents (solar + wind) per 1 GW capacity (Belgium)

That is all nice and well, but the big question is how much solar and wind capacity will be needed to be able to produce the same as a 1 GW nuclear reactor at its rated generating capacity? Just based on the current share of solar and wind, a capacity of 6.8 GW is needed in June and 5.6 GW in December.

Concluding, does our government want to add the equivalent of 1 large nuclear power plant per year? Purely comparing capacity, yes, they want to add a capacity of 1 GW of solar and wind per year and 1 GW is the capacity of a large Belgian nuclear power reactor. But when we look at the potential output of that 1 GW and compare it with the potential output of 1 GW nuclear, that is a completely different story.

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