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Science Forum

  1. 22 Feb '17 14:06 / 2 edits
    flexible wind turbine blades that are more energy efficient and can deal with a greater range of wind speeds than conventional hard blades;

    https://techxplore.com/news/2017-02-turbines-flexible-blades-efficient.html

    I am impressed.
  2. 22 Feb '17 15:57
    This highlights the fact that computer aided design still needs human input. I bet people have run automated searches through all sorts of stiff blade designs, but not thought to allow for flexible blades before.

    Do you know why turbines typically face into the wind? I foresee a problem with the blades striking the vertical pole if the blades are flexible.
  3. Standard member sonhouse
    Fast and Curious
    22 Feb '17 16:03
    Originally posted by twhitehead
    This highlights the fact that computer aided design still needs human input. I bet people have run automated searches through all sorts of stiff blade designs, but not thought to allow for flexible blades before.

    Do you know why turbines typically face into the wind? I foresee a problem with the blades striking the vertical pole if the blades are flexible.
    Well, not THAT flexible I would think. I would credit the designers, you know, the intelligent designers that they would have taken that into account.

    But those blades matched to the gearless turbines and there will be a revolution, especially of the blades
  4. 22 Feb '17 16:11
    Originally posted by sonhouse
    Well, not THAT flexible I would think.
    ANY increase in flexibility will require greater clearances.

    I would credit the designers, you know, the intelligent designers that they would have taken that into account.
    I am not saying the designers would be too stupid to see it, I am saying that it might be necessary to reverse the direction the turbine faces or increase the clearance between shaft and blades - which might increase costs. The fact is that the 'designers' have not yet designed a full scale working flexible blade turbine and the article clearly states that they do not yet know whether it is a commercially viable idea.
  5. 22 Feb '17 16:50 / 3 edits
    Originally posted by twhitehead

    Do you know why turbines typically face into the wind? I foresee a problem with the blades striking the vertical pole if the blades are flexible.
    They are not talking about making the leading edge of the blades bendy but rather the cross-section of the blades i.e. the tips of the blades will not go further back than the base of the blades when the wind blows. The extra clearance needed would only be a small fraction of the blade's width from leading edge to the tail edge, i.e. the length of the cross-section, not the length of the whole blade, so I doubt this would cause much increase in the necessary clearance distance. It obviously would depend on the size of the blade but we could be talking very roughly about just one extra metre of clearance for the larger ones.
  6. 22 Feb '17 19:16
    Originally posted by humy
    They are not talking about making the leading edge of the blades bendy but rather the cross-section of the blades .
    Ok, that makes sense.
    I wonder if rotating blades (along the blade axis) has the same effect. I suppose the idea here is that it is all automatic and thus possibly more efficient overall.
  7. Standard member sonhouse
    Fast and Curious
    22 Feb '17 23:04
    Originally posted by twhitehead
    Ok, that makes sense.
    I wonder if rotating blades (along the blade axis) has the same effect. I suppose the idea here is that it is all automatic and thus possibly more efficient overall.
    Has anyone done an efficiency analysis of those vertical mounted egg beater rotors?

    This link, they claim a 35% increase in efficiency, which I doubt but what about this idea? It seems to me to work no matter what the angle the wind is coming from so there is a design advantage right there:

    http://www.treehugger.com/wind-technology/new-eggbeater-vawt-design-claims-35-more-power-competitors.html
  8. 23 Feb '17 07:39
    Originally posted by sonhouse
    Has anyone done an efficiency analysis of those vertical mounted egg beater rotors?
    The key words are: "at the same price point and swept area".
    A standard three blade design has a very large 'swept area'. To build an egg beater with the same swept area would be virtually impossible with the very large turbines.
    I believe the egg beater design is better only when you need a small turbine in confined space.
  9. Standard member sonhouse
    Fast and Curious
    23 Feb '17 08:32
    Originally posted by twhitehead
    The key words are: "at the same price point and swept area".
    A standard three blade design has a very large 'swept area'. To build an egg beater with the same swept area would be virtually impossible with the very large turbines.
    I believe the egg beater design is better only when you need a small turbine in confined space.
    Well, if it could generate say 5 kw 24/7 for a single home, there would be plenty of energy for the house plus enough to feed the excess to the grid. Multiply that times a few hundred million, it might be enough to make us totally free of all other sources like nuclear and such.

    A billion such turbines, that would be 5 terawatts. Still not enough to run a whole civilization but it could be significant.
  10. 23 Feb '17 09:13
    Originally posted by sonhouse
    Well, if it could generate say 5 kw 24/7 for a single home, there would be plenty of energy for the house plus enough to feed the excess to the grid. Multiply that times a few hundred million, it might be enough to make us totally free of all other sources like nuclear and such.

    A billion such turbines, that would be 5 terawatts. Still not enough to run a whole civilization but it could be significant.
    Unlike solar, wind power is typically not suitable for household installation. Not only is it bulky, but most locations simply don't have enough wind. The sun shines more or less equally everywhere with some variation by latitude, but wind is very variable. Wind currently works best in large wind farms sited appropriately. And yes, wind could supply a significant proportion of our electrical needs and is currently the cheapest source of energy there is.

    For households, solar is the best option and is already cheaper than buying power from your local utility. Have you contacted SolarCity yet to see what deal they can offer you?
  11. 23 Feb '17 09:18
    Cape Town has strong winds much of the time, so wind power would be a good idea here. The problem is that it is not reliable, ie there could be days with little or no wind, so battery backup would not be sufficient. It would be necessary to remain connected to the grid and would only be viable with a feed in tariff. But local councils resist allowing feed in tariffs because they make money off electricity and do not want people to install their own solar or wind power. Politics doesn't favour green energy.