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Monster Wind Turbine Blades Could Help Offshore Wind Compete with Fossil Fuels

17 points by iProject 14y ago

startupfounder 14y ago
I've repelled off wind turbines inspecting 40 meter blades and they are massive. I hope they really get their process down for mass production, because many of these blades are low quality and need to be replaced under warranty. Ice is obviously a major issue with this size, for both the balancing of the turbine and for a potential hazard to passers by.
- jessaustin 14y ago
  Presumably there aren't too many passers-by in an offshore installation. Couldn't the blades be heated using some of the power produced by the turbine?
  - akoumjian 14y ago
    IIRC this is in fact done in some commercial turbines.
  - startupfounder 14y ago
    1) What you really have to worry about is the maintenance staff, people are in, on and around wind turbines all the time. If you are not able to maintain them due to the dager of ice buildup then the longevity of the turbines decrease. 2) It is kind of funny, but on all of the wind turbines I have been on, for complex reasons I will not get into here, don't use any of the energy they produce. They pull power from the grid to run internal computers and lighting.
    - jessaustin 14y ago
      One challenge I would expect is the difficulty of running current from the (relatively) stationary generator (or the grid if the generator's power isn't suitable) to the rotating blades. You can't just use a wire; it would get wound around until it broke. Presumably there could be some sort of slip ring, or perhaps an inductive circuit like that found in Reelights. Of course the engineers have already solved the similar problem of running power to and from the hub that must rotate to face the wind, but that rotation is much slower than that of the rotating blades.
- andrewcooke 14y ago
  rapelled? (still sounds terrifying - presumably they were stationary?)
  - sopooneo 14y ago
    I assume OP means repelled down the tower, not the blades.
    - defrost 14y ago
      Rapelled, as in abseiled down on a rope, rather than repelled, as in forced away from.
    - startupfounder 14y ago
      Nope, I do in fact mean the blades. Because blades are made up of 13 tons of fiberglass they bend and vibrate a lot. You have to visually inspect the blades to make sure there are no cracks or de-lamination. If there are you have to do the repairs while on rope in winds blowing up to 12 m/s. It is in fact an extremely safe industry, Industrial Rope Access. With over 25m man hours on rope around the world there has only been 1 death offshore in the north sea in 2011.
  - startupfounder 14y ago
    Yes, stationary. When you lock out a wind turbine you stop the rotation by pitching the blades back to 0 or break them so that they do not generate any power, second you apply a giant hydraulic break. But this is not enough. The last thing you do is put a missive steal pin ~6" diameter by 12" long through a very large disk with many ~6" holes that is attached to the main shaft going from the hub (where the three blades are attached) to the gearbox (that has a 70:1 gear ratio). Only then are you able to tie anchors to the generator, bring the ropes up on top of the nacelle and rappel off the 250' to the ground.
ricw 14y ago
I'm unsure how exactly this is supposed to be news. Of course economies of scale are going to pay off. Of course better technology is going to pay off. But how in earth and when is it going to compete with fossil fuels? No answer. Rubbish article. Sorry for the rant.
andrewcooke 14y ago
As wind turbines get bigger, the loads on the blades, and therefore their weight, goes up exponentially. is that true? i would have expected it to be some fixed power, like length^3. exponential means (technically) that it goes as k^length. maybe here it just means "quickly"?
- ars 14y ago
  I think it is actually exponential. The longer the blade the heavier it is, so the stronger it has to be, which means more material, which makes it heavier, so you need even more material for strength. A feedback loop like that means exponential. The volume goes up as length^3, but the strength has to go up faster than that, since the end of the blade must hold the entire weight plus the weight of the piece next to it, which also got heavier as it got longer.
  - andrewcooke 14y ago
    good point; you could well be right. thanks.
  - eric-hu 14y ago
    What other feedback loops like that have exponential growth?
    - dwiel 14y ago
      Amount of fuel in a rocket necessary to send a mass X into orbit? I dont know the math, but i've heard the exact same feedback explination used.
      - eric-hu 14y ago
        My mind went there too. I didn't mention that one because it doesn't seem to be exponential. I actually found a past entry on the xkcd what-if blog: http://what-if.xkcd.com/7/ http://what-if.xkcd.com/7/ For a given amount of ship mass, you need 20x that mass in fuel to get it into space. That seems to be multiplicative growth, unless I'm interpreting something wrong.

17 points by iProject 14y ago

I've repelled off wind turbines inspecting 40 meter blades and they are massive. I hope they really get their process down for mass production, because many of these blades are low quality and need to be replaced under warranty. Ice is obviously a major issue with this size, for both the balancing of the turbine and for a potential hazard to passers by.

jessaustin 14y ago
Presumably there aren't too many passers-by in an offshore installation. Couldn't the blades be heated using some of the power produced by the turbine?
- akoumjian 14y ago
  IIRC this is in fact done in some commercial turbines.
- startupfounder 14y ago
  1) What you really have to worry about is the maintenance staff, people are in, on and around wind turbines all the time. If you are not able to maintain them due to the dager of ice buildup then the longevity of the turbines decrease. 2) It is kind of funny, but on all of the wind turbines I have been on, for complex reasons I will not get into here, don't use any of the energy they produce. They pull power from the grid to run internal computers and lighting.
  - jessaustin 14y ago
    One challenge I would expect is the difficulty of running current from the (relatively) stationary generator (or the grid if the generator's power isn't suitable) to the rotating blades. You can't just use a wire; it would get wound around until it broke. Presumably there could be some sort of slip ring, or perhaps an inductive circuit like that found in Reelights. Of course the engineers have already solved the similar problem of running power to and from the hub that must rotate to face the wind, but that rotation is much slower than that of the rotating blades.
andrewcooke 14y ago
rapelled? (still sounds terrifying - presumably they were stationary?)
- sopooneo 14y ago
  I assume OP means repelled down the tower, not the blades.
  - defrost 14y ago
    Rapelled, as in abseiled down on a rope, rather than repelled, as in forced away from.
  - startupfounder 14y ago
    Nope, I do in fact mean the blades. Because blades are made up of 13 tons of fiberglass they bend and vibrate a lot. You have to visually inspect the blades to make sure there are no cracks or de-lamination. If there are you have to do the repairs while on rope in winds blowing up to 12 m/s. It is in fact an extremely safe industry, Industrial Rope Access. With over 25m man hours on rope around the world there has only been 1 death offshore in the north sea in 2011.
- startupfounder 14y ago
  Yes, stationary. When you lock out a wind turbine you stop the rotation by pitching the blades back to 0 or break them so that they do not generate any power, second you apply a giant hydraulic break. But this is not enough. The last thing you do is put a missive steal pin ~6" diameter by 12" long through a very large disk with many ~6" holes that is attached to the main shaft going from the hub (where the three blades are attached) to the gearbox (that has a 70:1 gear ratio). Only then are you able to tie anchors to the generator, bring the ropes up on top of the nacelle and rappel off the 250' to the ground.

ricw 14y ago

I'm unsure how exactly this is supposed to be news. Of course economies of scale are going to pay off. Of course better technology is going to pay off. But how in earth and when is it going to compete with fossil fuels? No answer. Rubbish article. Sorry for the rant.

andrewcooke 14y ago

As wind turbines get bigger, the loads on the blades, and therefore their weight, goes up exponentially. is that true? i would have expected it to be some fixed power, like length^3. exponential means (technically) that it goes as k^length. maybe here it just means "quickly"?

ars 14y ago
I think it is actually exponential. The longer the blade the heavier it is, so the stronger it has to be, which means more material, which makes it heavier, so you need even more material for strength. A feedback loop like that means exponential. The volume goes up as length^3, but the strength has to go up faster than that, since the end of the blade must hold the entire weight plus the weight of the piece next to it, which also got heavier as it got longer.
- andrewcooke 14y ago
  good point; you could well be right. thanks.
- eric-hu 14y ago
  What other feedback loops like that have exponential growth?
  - dwiel 14y ago
    Amount of fuel in a rocket necessary to send a mass X into orbit? I dont know the math, but i've heard the exact same feedback explination used.
    - eric-hu 14y ago
      My mind went there too. I didn't mention that one because it doesn't seem to be exponential. I actually found a past entry on the xkcd what-if blog: http://what-if.xkcd.com/7/ http://what-if.xkcd.com/7/ For a given amount of ship mass, you need 20x that mass in fuel to get it into space. That seems to be multiplicative growth, unless I'm interpreting something wrong.