Was it a bird? Was it a plane? Perhaps a flying cow? So far, nothing has been discounted in the mysterious case of damage to the blades of a wind turbine in Conisholme in Lincolnshire.
Whatever it was happened at the weekend left the turbine without one of its 20m blades and another bent and gnarled. Ecotricity, the turbine's owners, cannot yet explain what happened. Dale Vince, founder of the renewable energy company, said on the BBC's Today programme that, whatever hit the blades it was "probably the size and weight of a cow".
Others suggested that it could be a meterorite, though there is no crater, or perhaps falling ice from a passing aeroplane. Another theory is that metal fatigue in the blades caused the failure, with perhaps one blade falling off and denting the other.
Vince said: "It would have to be a catastrophic failure. That turbine has been running for a year now so we think that's pretty unlikely as well."
The forces on a modern turbine are huge, so damage to the blades is not unheard of. They typically spin at around 25 rpm (which translates to a few million times a year) and the lift on the blades is comparable to that on the wing of a jumbo jet. In February last year, a 200ft wind turbine near Ĺrhus in Denmark fell apart in high winds when a loosened blade smashed into the central tower and caused the whole structure to collapse.
The year before, a 200ft turbine at a wind farm in Kintyre collapsed last November in a 50mph wind.
Vince has so far only one possibility — that the turbine might have been hit by lightning. "Lightning can do that but there are no obvious signs of lightning so we've ruled that out."
Among the more exotic ideas are reports from locals of strange lights in the sky at the weekend. A turkey farmer from North Somercotes raised the possibility of UFOs though this might have a simpler explanation, the result of fireworks to celebrate a local's birthday.
Robert Palmer, leader of East Lindsey district council and member of Lincolnshire county council, wants a formal investigation into what happened. "I would be very interested to find out what it was," he said. "If we are being looked at by other people, by other planets, it would be interesting to find out why they have chosen this part of the country. It's a rich agricultural part of the country and we have got a concentration of turbines here which may have fascinated them. You just don't know, do you?
"I am not counting it out that it was a UFO. There are things out there that you cannot explain. I would have thought that if it was a UFO, it would have been more sophisticated than to drive in to the turbine."
The wreckage from Conisholme has been sent off for analysis by Ecotricity.
The Ministry of Defence has said it is not concerned enough to launch its own investigation, but armchair detectives are sure to continue to speculate.
Speculation grows over mysterious wind turbine damage | Environment | guardian.co.uk
Speculation grows over mysterious wind turbine damage
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