We sell wind turbines. For four days at the end of June, across most of Western Europe, wind was the thing that wasn't there — and the grid came closer to failing than most people noticed. That is an uncomfortable story for a wind company to tell. It is also the most useful one we have written this year.
A static high-pressure system parked itself over Western Europe. High pressure brings heat, and heat brings air conditioning. It also brings still air. Those two things arrive together, and that is the whole problem in a sentence.
What a hot, still week does to a grid
In Great Britain on 23 June, system frequency slipped below 49.8 Hz for close to two hours — the point at which the operator starts spending serious money to hold the network together. Exports to the Netherlands were cut. The next day, the National Energy System Operator secured around 1.7 GW of imported electricity at roughly £1,400 per megawatt-hour. A normal summer afternoon trades in the tens of pounds.
In Belgium, wholesale prices passed €1,000/MWh — the highest in six years.
Heat doesn't break one thing. It breaks everything at once.
This is the part that got the least attention, and it matters the most.
France's nuclear fleet cools itself with river water and returns that water warmer than it found it. When the Rhône, the Garonne and the Seine climb towards their regulatory ceiling of roughly 28°C, EDF is legally obliged to throttle back. In late June, air temperatures at France's river-cooled sites reached 42.5°C. EDF cut about 4 GW, around 6% of the national fleet. The afternoon surplus France normally exports to its neighbours fell from 11–12 GW to under 3 GW.
The cushion France normally exports to its neighbours, before and during the heat. Sources: Montel News; pv magazine.
Gas was no better, for a reason that has nothing to do with fuel supply. A gas turbine's output depends on the density of the air it draws in, and hot air is thinner. Run the same machine at 40°C instead of 20°C and it loses roughly 13% of its capacity and about 7% of its efficiency. British gas plants ran derated through the worst of it — at precisely the hours they were most needed.
And wind, our own product, was the quietest contributor of all. In a quarter when British renewables had just set a record — 53.1% of generation, with wind alone at 35.6% — the heatwave days saw wind fall away to a fraction of that.
Nuclear, gas and wind all faltered in the same week, for the same reason, at the same hour. That is not a wind problem. It is a one-source problem.
The part that concerns us directly
We would rather you heard this from us than worked it out later. Peer-reviewed work published this February, modelling European wind under CMIP6 climate projections, finds that wind droughts — long spells of unusually low wind — are becoming more frequent and longer-lasting, with German summers singled out. Anyone selling wind turbines in Europe ought to be able to say that out loud.
So here is what we think it actually means. It is not “buy a turbine”.
One source is the risk — not one technology
The useful thing about a heatwave is that it is exactly when solar is at its best. Still air and cloudless skies are the same weather. The conditions that quiet our turbines are the conditions that push a solar panel towards its peak. They are close to opposites, which is precisely why owning both beats owning either.
That is not a sales pitch bolted onto a news story. It is the reason we sell flexible solar panels alongside turbines rather than instead of them.
And measure before you buy anything
Wind is site-specific in a way solar simply isn't. Two houses on the same street can differ by a factor of two. Any annual output figure we quote is a guess about your roof — and a guess we have an obvious interest in getting wrong.
So measure first. An anemometer costs a small fraction of a turbine and will tell you within a season whether your site is worth it. Then put your own numbers into the calculator on the Atlas and Magnum pages — your wind, your electricity price, your roof. It will tell some of you that a turbine won't pay for itself where you live. We would rather it told you that now than we did after you had bought one.
The last week of June was not an argument against wind, and it was not an argument for it either. It was an argument against depending on any single thing — one fuel, one technology, one river, or one grid that has to pay £1,400 a megawatt-hour on the hottest afternoon of the year. The households that barely noticed it were the ones generating something of their own, from more than one source.
Hero photograph: Adobe Stock. Illustrative — not a photograph of the plants affected in June.