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I wonder if balloon wind turbines might not be a better approach in those circumstances. You have to accept smaller blades but I'd think the other advantages w

I wonder if balloon wind turbines might not be a better approach in those circumstances. You have to accept smaller blades but I'd think the other advantages would be worth it.

flavius29663 5y ago
Wind turbines output grows with the size of the blade (it's squared). http://large.stanford.edu/courses/2011/ph240/parise1/ http://large.stanford.edu/courses/2011/ph240/parise1/ edit: When you take into account that the blade size increase means a higher tower (and thus higher wind speeds), the increase is more staggering, because wind speed is cubed in the final output: > Combining the effects of height and blade length, doubling the height and doubling the blade length will result in an increase of power over 22 fold. This is why companies try so hard to build bigger blades, higher. Current blades are just massive https://cdn.vox-cdn.com/uploads/chorus_asset/file/10382023/Wind_turbine_heights.jpg https://cdn.vox-cdn.com/uploads/chorus_asset/file/10382023/W... The wingspan of a 747 is 68 meters. The newest GE turbine has a diameter of 220 meters, each blade is 107 meters. One blade is 50% longer than the whole wingspan of 747. You can fit 3x747 planes inside the area swept by a current turbine. This is why Google's Makani project never took off...I really hoped for that project to succeed, it was very cool, but there is no way to compete with the bladed giants. edited to address cjbest and baq valid comments
- cjbest 5y ago
  I think you meant it grows as the square of the blade length (and the cube of the wind speed) From your link: > Thus, the power passing through the blades of the turbine, and thus in turn the power of the electricity the turbine generates, is proportional to the square of the length of the blades: a doubling of blade length leads to a quadrupling of wind power passing over the blades. Doesn’t change your conclusion of course. Thanks for the interesting link!
  - flavius29663 5y ago
    you're right, and I roughly knew that, I just didn't knew how to express it well enough in a short manner. When you increase the blade you also have access to higher winds, so the total output is much much bigger. I was focusing on the quote below and I didn't knew how to express it better. > Combining the effects of height and blade length, doubling the height and doubling the blade length will result in an increase of power over 22 fold.
- baq 5y ago
  > grows exponentially with the size of the blade (it's cubed). sorry, couldn't resist nitpicking. you're contradicting yourself here :)
  - adrianmonk 5y ago
    If only it were exponential... build one REALLY big blade and power the whole earth.
- kitd 5y ago
  The newest GE turbine has a radius of 220 meters, each blade is 107 meters. My last maths class was decades ago, but ... 'diameter'?
  - flavius29663 5y ago
    ha, I think I need more coffee this morning. Or maybe i was just too excited to type that out, finally something I know a little bit about on HN
mLuby 5y ago
I did a research project on this. Aerial wind turbines have two key advantages over terrestrial ones: access to steady high-speed winds at altitude, and limited ground footprint. But floating or flying imposes limits on their size and efficiency. So they only fit niche uses in nomadic settings, like a temporary research camp. But then it's probably cheaper and more reliable to just use a fuel-powered generator. Also they're a bit of a hazard to aircraft (and each other if not steerable), are more at risk to storms, and the floating ones require expensive or explosive lifting gas. Too bad, because I think they're beautiful!
LinAGKar 5y ago
Yes, floating ones won't rise higher than to the surface.

I wonder if balloon wind turbines might not be a better approach in those circumstances. You have to accept smaller blades but I'd think the other advantages would be worth it.

flavius29663 5y ago

Wind turbines output grows with the size of the blade (it's squared). http://large.stanford.edu/courses/2011/ph240/parise1/ http://large.stanford.edu/courses/2011/ph240/parise1/ edit: When you take into account that the blade size increase means a higher tower (and thus higher wind speeds), the increase is more staggering, because wind speed is cubed in the final output: > Combining the effects of height and blade length, doubling the height and doubling the blade length will result in an increase of power over 22 fold. This is why companies try so hard to build bigger blades, higher. Current blades are just massive https://cdn.vox-cdn.com/uploads/chorus_asset/file/10382023/Wind_turbine_heights.jpg https://cdn.vox-cdn.com/uploads/chorus_asset/file/10382023/W... The wingspan of a 747 is 68 meters. The newest GE turbine has a diameter of 220 meters, each blade is 107 meters. One blade is 50% longer than the whole wingspan of 747. You can fit 3x747 planes inside the area swept by a current turbine. This is why Google's Makani project never took off...I really hoped for that project to succeed, it was very cool, but there is no way to compete with the bladed giants. edited to address cjbest and baq valid comments

cjbest 5y ago
I think you meant it grows as the square of the blade length (and the cube of the wind speed) From your link: > Thus, the power passing through the blades of the turbine, and thus in turn the power of the electricity the turbine generates, is proportional to the square of the length of the blades: a doubling of blade length leads to a quadrupling of wind power passing over the blades. Doesn’t change your conclusion of course. Thanks for the interesting link!
- flavius29663 5y ago
  you're right, and I roughly knew that, I just didn't knew how to express it well enough in a short manner. When you increase the blade you also have access to higher winds, so the total output is much much bigger. I was focusing on the quote below and I didn't knew how to express it better. > Combining the effects of height and blade length, doubling the height and doubling the blade length will result in an increase of power over 22 fold.
baq 5y ago
> grows exponentially with the size of the blade (it's cubed). sorry, couldn't resist nitpicking. you're contradicting yourself here :)
- adrianmonk 5y ago
  If only it were exponential... build one REALLY big blade and power the whole earth.
kitd 5y ago
The newest GE turbine has a radius of 220 meters, each blade is 107 meters. My last maths class was decades ago, but ... 'diameter'?
- flavius29663 5y ago
  ha, I think I need more coffee this morning. Or maybe i was just too excited to type that out, finally something I know a little bit about on HN

mLuby 5y ago

I did a research project on this. Aerial wind turbines have two key advantages over terrestrial ones: access to steady high-speed winds at altitude, and limited ground footprint. But floating or flying imposes limits on their size and efficiency. So they only fit niche uses in nomadic settings, like a temporary research camp. But then it's probably cheaper and more reliable to just use a fuel-powered generator. Also they're a bit of a hazard to aircraft (and each other if not steerable), are more at risk to storms, and the floating ones require expensive or explosive lifting gas. Too bad, because I think they're beautiful!

LinAGKar 5y ago

Yes, floating ones won't rise higher than to the surface.