Is there a latent problem with wind turbines?

In a posting “Accelerated Depreciation” Bishop hill says

This article at a blog called Billo The Wisp is important if true. Turbine gearbox failures apparently happen typically after 5-7 years rather than the 20 years that we are normally led to believe wind turbines last for. Moreover, their failure can be completely catastrophic, leading to the destruction of the whole turbine.

My comment is quite sceptical.

I do not think that the thrust of this post is correct – that there is a problem that gearboxes in that they will only last for 5-7 years, that has been around for 25 years and that it was so serious that the US government set up a special department to investigate in 2007. Despite all of this, there is still a largely hidden and hugely costly problem of which people are not aware. Having been in the engineering industry for a number of years I would consider the following if involved in the decision to set up a wind farm.

First, wind turbines are electro-mechanical devices. They need servicing and occasional overhauling. Ease of maintenance is important, including the replacement of major components. I would want a recommended maintenance program, along with projected parts costs, required maintenance equipment (e.g. a crane) and standard labour hours.

Second, I would want data on long-term historical performance, service and maintenance costs of each manufacturer’s equipment.

Third, if there was a large wind farm, I would include some spare parts, including major components that should last the life of the equipment. This may include have complete sets of spare parts that can be quickly swapped out – so major maintenance can be done in a workshop and not 200 metres in the air.

Fourth, I would cross-check this against industry journals. Wind turbine manufacture is a huge business with a number of manufacturers selling into a large number of countries. Issues are discussed, like in any industry.

The largest wind farms cost hundreds of millions. Businesses are not naïve. Even with large potential profits, there is always more money to be made through proper investment appraisal and protecting that investment through a thorough maintenance programme. If a major component of a wind turbine only lasted a third the length of time of the main structure, then replacing that component would become a part of the life-time costs. There would be huge incentives to minimize those costs through better design, such as ease of replacement of bearings. The only issue is that the real costs of wind turbines will never come down to a level where subsidies are no longer required.

NB a source of the reliability claims is this June 2010 article, which is now 3.5 years old.


  1. Brian H

     /  08/01/2014

    Onshore wind farms are bad enough. Wait till it turns out offshore ones last even less time. (<<10 years) Wanna bet ANY will be repaired?

    • manicbeancounter

       /  08/01/2014

      If it is the mechanics in the head then they will be repaired. Offshore wind turbines generate about £140 ($220 MWh) in revenue. The majority is index-linked. For a 2 MWh pylon at average 35% of capacity that means £430k ($700k) in revenue. The vast majority of the cost is for the pylon which is typically sunk 30 metres into the sea bed. So even if it was a million pounds every five years for maintenance, the alternative is the complete write-off of maybe £5m of investment.
      But this problem has been known about for years. Yet in the UK investment is still accelerating

      • Brian H

         /  10/01/2014

        It won’t take more than one or two losses of ships or lives to change the calculus.
        The investment is accelerating predicated on short-term returns, AKA gaming the government, not long-term viability.

  2. Hey beancounter – 8760 hrs x 35% x 2MW x £140 per MWh = £858k revenue per annum… or did I misunderstand you?

    I presumed “£140 ($220 MWh) in revenue” meant “£140 ($220) per MWh in revenue”.

    Where did you get that figure from btw?

    • manicbeancounter

       /  30/01/2014

      You have not misunderstood me on the potential revenue. This is for offshore wind turbines.
      The figure of £140 per MWh comes in two parts.
      1. The subsidy that large scale renewables receive is called Renewables Obligation Credits ROCS. The regulator OFGEM sets the rates. The current rate of £42.02 is found here. The DECC published recently statistics at “renewable energy trends” has spreadsheet “Renewables obligation: certificates and generation (ET6.3)”. Here you will see that new offshore wind farms receive 2 ROCs, or £84, per megawatt hour generated.
      2. All electricity generated is sold wholesale. The current price is about £55 per megawatt hour.

      Onshore wind turbines generate a lot less revenue. They only attract 1 ROC per MWh, and, in England, average output is 26% of capacity. But then they are cheaper to build than the offshore variety.

%d bloggers like this: