Claim: 8 GW offshore wind capacity corresponds to 8 nuclear reactors

A couple months ago, I wrote about the claim of our Minister of Energy that 1 GW of renewable capacity equals 1 large nuclear power plant (she obviously meant “reactors”). I recently came across a variation on this claim made by another member of our Government, the Minister of the North Sea (at least the stretch of the North Sea that belongs to Belgium). Here is what he said about the future plans for wind power in the North Sea as reported by a journalist of a Flemish newspaper (translated from Dutch, my emphasis):

According to Van Quickenborne (Minister of the North Sea), it is even possible to reach 8 gigawatts with a third wind farm by 2040. “This capacity is enormous, it would correspond to 8 nuclear reactors,” says the Open VLD politician, who believes this is enough to supply all Belgian families.

This seems impressive at first glance. Basically, the total capacity of wind mills on the Belgian part of the North Sea is expected to amount to 8 GW by 2040, which the Minister then compares to the capacity of 8 nuclear reactors.

There is a core of truth in this claim (our largest nuclear reactors have a capacity of 1 GW each, so 8 GW would correspond to 8 of those), but it is pretty misleading. It is comparing two different types of electricity generation having a (radically) different output.

I often wonder whether our politicians understand the difference between intermittent and dispatchable power. This question again rose up when reading the article. The quote above ended with the journalist paraphrasing the Minister that 8 GW capacity is enough to supply all Belgian families. The next sentence came as a complete surprise to me:

Only, then the wind should always have to blow.

I am not sure who made this remark. It is not in quotes, but it follows the journalist paraphrasing the Minister. It could be that the Minister made this remark, but it could also be the journalist. Unfortunately, I was not able to view the original interview. The journalist of the Flemish newspaper didn’t conduct the interview himself, he just reported on an interview of the Minister by a journalist of Sudinfo (a Walloon newspaper). That article is for subscribers only, so I could not verify what was said exactly in the interview.

This tiny sentence that was so laconically added to the article is intriguing to me. It opens the slight possibility that, although unlikely, this enlightening insight came from the Minister himself. It is more likely that it came from one of the two journalists who -one can hope- saw through the misleading claim of the Minister and interjected this remark in his article.

The claim is surely misleading and one doesn’t need to scratch too deep to figure that out. Belgium currently has 6 GW of nuclear capacity and this is enough to provide half of total Belgian electricity demand, so 8 GW of nuclear capacity would be able to provide two thirds of total Belgian electricity demand.

Now, compare this to the potential output of offshore wind. We learned from the Minister that the 8 GW of offshore wind capacity would be able to supply all Belgian families. Electricity demand of households was 23% of total Belgian electricity demand in 2021, so that 8 GW of offshore wind capacity would be able to provide about one third of what the same capacity of nuclear would provide. Although their capacity is the same, the 8 GW offshore wind capacity would correspond to just 3 large nuclear reactors (closer to 2 large and a small one).

That is still misleading: not only the quantity, but also the quality of the output of the two is radically different. Here is the output of both offshore wind and nuclear in 2021, normalized to a capacity of 8 GW:

It is clear that the output range of offshore wind is much larger than that of nuclear. The nuclear output would be between 5.6 and 8 GWh with an average capacity factor of 91%. The output of offshore wind is all over the place and would be between 0 and 7.8 GWh with an average capacity factor of 34% (confirming that the output of offshore wind is about one third of the output of nuclear).

That is why I think the claim that 8 GW offshore wind capacity corresponds to 8 nuclear reactors is misleading: by comparing both capacities and not taking their potential output into account, the claim might trick some people into believing that this 8 GW offshore wind capacity is enough to replace 8 GW of nuclear capacity, which is obviously not the case.

It is however possible to compare this offshore wind capacity to 8 nuclear reactors, but then 8 reactors that break down on a regular basis. That is however not a favorable comparison for those whose goal it is to remove nuclear capacity from our electricity infrastructure…

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