OK, so: Betz's Law says that the maximum energy that any wind turbine can extract is 16/27 of the kinetic energy contained in the wind that it blocks. Modern three-blade wind turbines reach 75-80% of the theoretical maximum, across the entire area their rotors sweep out.[1]
That's why the classic windmill design is so classic: its efficiency scales with the square of the length of the rotors. The energy extracted by a windmill is (very roughly):
wind_speed * 16/27 * 0.8 * π * rotor_length^2
But then the wind speed also increases with height.[2] So the game to design an efficient windmill is to sweep out as much cross-sectional area as possible, as high up in the air as possible, and that's how we get the iconic windmills we have.
I don't know anything about anything -- I just read this stuff on Wikipedia. But until a third-party engineer says otherwise, I'm super skeptical that a device like this with minimal high-altitude cross-section is anywhere in the game.
The article did say it's less efficient, but you can put twice as many in the same space which supposedly more than makes up for the power deficit. Plus no noise pollution or threat to birds and lower maintenance costs. Obviously a lot of technologies look good at this point, before they are widely deployed and tested, but I wouldn't count it out yet.
My first thought was "even if this is less efficient, the silence and lack-of-bird-killing means it would be viable to install places where NIMBYism etc. mean that traditional turbines can't be".
i.e. it may be sufficiently in the game to compete effectively against "no turbines" even if it can't compete against turbines directly.
Same here. I've also read up on a lot of different designs, and have been paying attention for a while now.
There are a couple of points that have occurred to me about wind power. 1) Most supposedly exciting, new designs are minor variations on older designs with minor improvements in efficiency. 2) Some esoteric design are actually good for something, but not for massive wind farms. Think wind turbine as art in a public park, etc. 3) Media love esoteric designs and want to hype it as the next thing, even though they are nowhere near the efficiency of a big 3-blade on a tall pole design.
Betz's Law applies to turbines, but it this thing really a turbine? "No moving parts" and the fact that it operates via oscillation rather than rotation implies that this is not in fact a turbine. If it is not a turbine then there is no reason to assume Betz's Law must apply to it, perhaps there is something else that governs efficiency in this case?
I followed the debate about renewables for quite some time and I heared stories like this before. A new design for wind energy with so obvious advantages. And you can read pretty similar stories for new solar or water power tech also pretty regularly.
I remember that already in the 90s I heared people saying that future wind turbines will have a funnel to focus the energy. Later kite-like flying turbines or turbines in donut-shaped balloons became a thing.
But wind turbines still basically look very similar than they used to be all the time, the biggest change is that they became much bigger. There's a reason for that: The design worked well and has been improved in details over the years. It's much easier to improve in small steps than to reinvent a completely new tech, which will have many downsides that the enthusiasts inventing them don't want to see.
That's not saying that it's entirely impossible that a completely new design of wind turbines will some day emerge. But I don't think it's very likely. And before I believe it I want to see them built at scale for a reasonable price. (Because one of the biggest advantages of the existing wind turbines - appart from them being environmentally friendly - is that their price dropped rapidly in the past years.)
Fluids tend to move as vortices so often reciprocating motion can be at least as efficient as rotary motion. For example it is (currently) difficult to replicate the efficiency of birds and fish with propellers.
Potentially (ahem) it's possible to extract work from ions in a flow, and if it's laminar there would be no vortex losses. Just for fun, here is an electrostatic turbine, which works a bit like an electrohydrodynamic (EHD) drive but in reverse. From what I understand, it's difficult to extract more work than it takes to ionize the fluid, so this cheats a bit by using liquid droplets:
[+] [-] JackC|11 years ago|reply
That's why the classic windmill design is so classic: its efficiency scales with the square of the length of the rotors. The energy extracted by a windmill is (very roughly):
But then the wind speed also increases with height.[2] So the game to design an efficient windmill is to sweep out as much cross-sectional area as possible, as high up in the air as possible, and that's how we get the iconic windmills we have.I don't know anything about anything -- I just read this stuff on Wikipedia. But until a third-party engineer says otherwise, I'm super skeptical that a device like this with minimal high-altitude cross-section is anywhere in the game.
[1] http://en.wikipedia.org/wiki/Betz%27s_law [2] http://en.wikipedia.org/wiki/Wind_profile_power_law
[+] [-] dmethvin|11 years ago|reply
[+] [-] mst|11 years ago|reply
i.e. it may be sufficiently in the game to compete effectively against "no turbines" even if it can't compete against turbines directly.
[+] [-] dwc|11 years ago|reply
Same here. I've also read up on a lot of different designs, and have been paying attention for a while now.
There are a couple of points that have occurred to me about wind power. 1) Most supposedly exciting, new designs are minor variations on older designs with minor improvements in efficiency. 2) Some esoteric design are actually good for something, but not for massive wind farms. Think wind turbine as art in a public park, etc. 3) Media love esoteric designs and want to hype it as the next thing, even though they are nowhere near the efficiency of a big 3-blade on a tall pole design.
[+] [-] hcarvalhoalves|11 years ago|reply
[+] [-] qyv|11 years ago|reply
[+] [-] ColinWright|11 years ago|reply
https://news.ycombinator.com/item?id=9523877
[+] [-] hannob|11 years ago|reply
I remember that already in the 90s I heared people saying that future wind turbines will have a funnel to focus the energy. Later kite-like flying turbines or turbines in donut-shaped balloons became a thing.
But wind turbines still basically look very similar than they used to be all the time, the biggest change is that they became much bigger. There's a reason for that: The design worked well and has been improved in details over the years. It's much easier to improve in small steps than to reinvent a completely new tech, which will have many downsides that the enthusiasts inventing them don't want to see.
That's not saying that it's entirely impossible that a completely new design of wind turbines will some day emerge. But I don't think it's very likely. And before I believe it I want to see them built at scale for a reasonable price. (Because one of the biggest advantages of the existing wind turbines - appart from them being environmentally friendly - is that their price dropped rapidly in the past years.)
[+] [-] zackmorris|11 years ago|reply
http://www.instructables.com/id/Windbelt-Redux--21st-Century...
Fluids tend to move as vortices so often reciprocating motion can be at least as efficient as rotary motion. For example it is (currently) difficult to replicate the efficiency of birds and fish with propellers.
Potentially (ahem) it's possible to extract work from ions in a flow, and if it's laminar there would be no vortex losses. Just for fun, here is an electrostatic turbine, which works a bit like an electrohydrodynamic (EHD) drive but in reverse. From what I understand, it's difficult to extract more work than it takes to ionize the fluid, so this cheats a bit by using liquid droplets:
http://www.wired.co.uk/news/archive/2013-04/3/bladeless-wind...
[+] [-] dm2|11 years ago|reply
I assume the high-altitude ones could be higher than birds fly.
They could even be used as in-flight recharge stations for drones.
[+] [-] gweinberg|11 years ago|reply
[+] [-] PopeOfNope|11 years ago|reply
[+] [-] digi_owl|11 years ago|reply
I wonder if they should try painting them deep green or something.