What does it take to fix a 30-storey wind turbine with blades that weigh 17 tonnes?
A crane. And plenty of patience.
A work crew was stymied Wednesday, for the second day, in replacing a faulty bearing in the wind turbine at Exhibition Place.
Wednesday’s problem, ironically: Too much wind.
And with wet, stormy weather bearing down on Toronto, it may take until Saturday for the turbine to get repaired and running again.
The problem with the turbine, erected in December 2002, lies with a bearing that has worn out prematurely.
Changing a bearing that weighs 1.7 tonnes, and is encased in a hub 65 metres above ground, can be tricky.
The turbine’s owners – Toronto Hydro Energy Services, and the WindShare energy cooperative – hired a 500-tonne crane to do the job.
To get at the bearing, the crane must first lift off the turbine’s three blades, which have a combined weight of 17 tonnes.
Once the blades have been removed, the crane can lower the doughnut-shaped assembly at the hub of the turbine, which houses both the bearing and the turbine’s 30-tonne generator.
The new bearing will then be replaced on the ground, and the repaired doughnut hoisted back up the following day.
Unfortunately, when hoisting a set of rotors that are 52 metres across and weigh 17 tonnes, weather becomes a factor.
It’s unsafe to lift or lower the assemblies in winds blowing more that 10 metres a second, or 36 kilometres and hour.
Wednesday, by the time straps had been secured around the turbine blades to lift them off, an anemometer on the crane showed that the wind speed was too high for the lift.
Shortly after noon, the lifting straps had to be removed, and the crane told to stand by until the weather improves.
It was one more frustration for Evan Ferrari, a Windshare director and past president, who watched as the straps were cast off.
The co-op hadn’t expected to have to replace the nine-year-old bearing, he said. Unfortunately, its warranty had expired.
The upside, he said is that it could extend the life of the turbine by another 20 years.
The turbine is supposed to produce about 1,000 megawatt hours a year. It came up short in 2010, at 927 megawatt hours. It came in on target in 2009, at 1,064 megawatt hours, but missed in 2008, at 780 megawatt hours.
For 2010, the co-op says the turbine had revenue of $58,439, and rang up maintenance costs of $18,291. It didn’t release statements including interest, taxes, depreciation and amortization.
The current repairs will cost more than $200,000.
The turbine’s initial cost, including development and installation, was $1.8 million.
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