On a January morning in Zeewolde, a row of rainbow painted wind turbines stood in the flat polder landscape as they had for close to a quarter century.
Then one of them came down.
The tower snapped, and the top of the machine landed on the field, the service road and the slope of the dike below.
Nobody was hurt.
But what the investigation found inside was one of the stranger engineering stories in recent wind power history. So what does a loose hydraulic rod do to a spinning rotor?
What a loose hydraulic rod does to a spinning rotor
A pitch cylinder is the hydraulic arm that tilts a blade on its long axis, the way you might twist a ceiling fan blade to change how aggressively it bites the air. When the wind rises, the pitch system turns the blades out of the wind so the rotor stops making lift and the machine can be brought to a stop. On the morning of the collapse, the wind picked up hard and that control system failed entirely.
Because the blades could no longer be moved into a safe position, they caught too much wind. A mechanical brake engaged but could not hold the rotor.
The machine then produced roughly twice as much power as it was built for before the generators dropped out. One blade broke off, the rotor went badly out of balance, and the upper section tore away from the tower. The whole sequence, from runaway rotor to collapsed tower, followed from one fitting that had worked loose.
The rainbow machines and the missing second control circuit
The Eemmeerdijk farm was built in the late 1990s and originally held 19 turbines strung along the dike, 17 of which were still standing when the accident happened. It was the only farm left in the Netherlands running this particular Dutch built model, and it was known for its towers, each painted a different color said to represent the surrounding countryside.
They were two blade machines, and that is where the design argument sits. Modern turbines use three blades, each with its own pitch control system, so that if one blade’s controller fails the other two can bring the rotor to a standstill. One more independent circuit turns a stuck blade into a shutdown rather than a cascade.
The machine that fell had no such backup. The external investigation also left open questions about the turbine’s original design.
What the debris field and the investigation confirmed
Blades, nacelle and the top of the mast broke off close to eleven in the morning on January 4, 2023, landing on grassland, the service road and the dike slope. The regional fire brigade reported no injuries and no danger to traffic on the dike road.
Certification body DNV examined the wreckage and the turbine’s own operating data. The rod had been replaced during a service visit in October 2022, and the investigation found no adhesive residue on it, with thread locking compound also absent from the service inventory list. With the cylinder loose, mechanical braking alone could not slow the two blades.
The operator said it would inform other owners still running similar models and encourage them to review their safety measures. But a full inspection of the remaining machines made little sense: they were already scheduled for removal before October, when the permit expired.
Why age turned out not to be the answer here
The easy reading of a 25 year old turbine falling over is metal fatigue, and that is not what the investigation described. The part at the center of the failure was only a few months old. What mattered was that nothing else in the machine could take over once it stopped moving.
Modern three blade farms, including those now standing under flyways like the invisible highway above Iowa, carry one pitch drive per blade, each able to feather independently if the others fail. Work tracking offshore turbine foundations follows how these structures and their surroundings change over decades, asking similar questions about design margin and long term reliability. The lesson the operator drew was simple: a single fault should not be able to cause consequences on this scale.
What the collapse changed for the machines still standing
The 16 remaining rainbow towers were stopped immediately after the accident and never turned again. The farm was already on the decommissioning list, and after the incident that schedule was brought forward, with dismantling beginning in the summer ahead of the permit deadline.
The genuine curiosity of the Zeewolde event is how small the failing part was relative to what it controlled. A pitch cylinder rod is a component a person can carry. The rotor it steered swept a circle roughly 180 feet across on a machine rated at about a megawatt, and when the rod worked loose the design had nowhere else to turn.
Three blade turbines build that second chance into their geometry. The extra blade is not decoration. At Eemmeerdijk, the absence of a second independent pitch circuit was the whole story.
Read the whole thing?
Get the week's signal, not the noise
Our sharpest reporting on energy, climate and nature — free, once a week.
