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Sunday, 1 August 2010

Offshore wind turbines revisited.

Further to my post about these bird mincers, nowhere can I find actual costs of maintenance. All I find is statements such as this:

6.5.3    Serviceability

The service demand of the present generation of offshore wind turbines in terms of man-hours is in the order of 40 to 80 hours [7].� Service visits are paid regularly, (except in the more demanding first year) about every six months.� A more major overhaul will be undertaken every five years, and will take around 100 man hours to complete. [1].

100 man hours after 5 years of operation in a salt water environment. Utter Hogwash. It will take more than 100 man hours just to reach the turbine in question.


Their Scenario and assessment

Note: No hard and fast methods, just theoretical assessments.

My Scenario

Firstly you will have to open up the casing to gain access to the operating machinery. No small task if the covers are not secured by stainless steel fastenings and even then working several hundred feet above sea level has it's own risks.

Once the casing has been opened, the inspection has to be carried out.

What do you find? Oh dear, one of the main rotor shaft bearings has become damaged and requires replacing. Just by chance you have the exact spare lying around on your support vessel. Remember now you have budgeted for 100 hrs. Oh dear and now it's raining. All that water is now filling up inside the casing which houses the  machinery which comprises of a 6.6KV generator (6,600V) which abhors water. Better try and rig up a cover to protect it. Must have one in the boat somewhere. (If anyone of you have seen what a 6.6kv discharge is like, it comprises  a plasma arc at the same temperatures as the surface of the sun.)

So far we have the crew of the vessel, probably 4, at an hourly rate of say £50 per hour. A maintenance crew of 4 on average of £100 per hour. Trip to the turbine 3 hours. opening the casing 1 hour. Inspection 1 hour. Locating and lifting the bearing onto the turbine 1 hour. Securing the turbine from the effects of the weather, 1 hour. Probable time to renew bearing 24 hours. (Wildly optimistic). Insulation testing and closure 2 hours. Return to port 3 hours.

This of course does not address the problem of why the bearing failed in the first place.

And all this is in the summer months. Almost impossible for 6 months of the year.

I'm just an ex marine engineer. So what do I know?


  1. Tried copying these comments into my local rag North West Evening Mail and they won't publish them, bastards.

    Mind there are 135 of the white elephants rising up from the waters betwixt the Isle of Walney and the Isle of Man and the papers editor is a leftie so this may explain it.

    There are already about thirty out there from an earlier installation. They don't turn when its cold, they don't turn when its hot and they shut themselves down if it gets too windy!

    What's the bloody point?

    The local rag is obviously 'on message' 'in cahoots' 'being bribed' or whatever, bastards.

  2. Frank. Trying to make the media aware of the scam of wind turbines is like pissing into the non existent wind.

    Oh and don't get me started on the smoking ban.

    I like your articles. maybe one day we can have an honest politician that will see how this ban has been inflicted on us in the most shamefull way. I'm not holding my breath.

  3. "opening the casing, one hour"


    This assumes, I take it, perfectly lubricated fastenings correctly torqued, with no corrosion evident.

    After five years, x hundred feet about the North Sea, in the open air?

    I think even your figures are bit optimistic.

  4. I think you underestimate the size of these turbines.

    The nacelle is about the same size as a large van, or a small removal truck.

    You don't just open up the casing, you have to climb up a ladder inside of the tower to get into the nacelle from the inside.

    Everything you need to do preventative maintenance has to be hauled up by a winch, and major repairs requires a floating crane to lift the generator out.

    I agree, your estimates are light.

  5. I think the main bearings are lifted components, meaning they require replacement whether they are damaged or not after a certain period of time. I think the lift of most turbine main bearings is 5 years. A barge mounted crane is needed for this operation.

  6. I have some experience of these wind turbines in Denmark.

    About 5% of main bearings fail in the first 2 years of operation. The rotor has to be removed to replace the bearing. Offshore, you need a "lift boat" with a special crane to remove the rotor- the lift boat has legs that extend to the seabed and jack up the boat to make a stable platform for the crane. Etc etc- the bottom line is that it is not economical to replace the bearing- once it fails the whole turbine is shut down for good. There are dozens of them offshore Denmark that have been shut down for years now.

  7. I am enjoying this little snippet,
    "In the event of loss of turbine power generation or lost electrical grid connection, there is no power at the isolated turbine for maintenance work or to keep turbine systems running.� At Horns Rev, it is intended to have a back-up diesel generator sited on the substation platform to provide power should the electrical connection to shore be broken."

  8. Oh and if you are looking into the costings of runningth emincers, this looks interesting,
    Particularly given the intro to the Conference,
    "Most offshore wind farms to date have faced unexpected maintenance demands and seen costs rise sharply, to a level which would significantly delay or prevent new projects being profitable."

  9. Wherever I look the costs of maintenance are either glossed over or seem to outweigh any advantage of having wind turbines in the first place.

    Anyone know where I can get a small nuclear power plant that I can fit in my garden?

  10. For those that think my maintenance time estimates are light, I deliberately gave the best case scenario. I reckon just opening the casing would be an absolute nightmare in itself.

    As for craneage. It doesn't bear thinking about if done from a ship even in light swells.

  11. Maintenance costs are the 'Incovenient Truth' of offshore wind.


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