Slashdot Mirror
Harvesting Energy in the Sky
withoutfeathers writes "The Economist magazine has an article on Flying wind farms. Mind you, we're not talking about ordinary, terrestrial windmills here. We're talking about actual airborne — up to 10km in the sky — wind farms intended to harvest the immense supply of energy in the jet stream. On the surface, the idea seems a little eccentric but, in fact, San Diego (California, US) based Sky WindPower has, apparently, thought their concept through pretty thoroughly and believes they can not only make this work, but do so profitably. The article discusses several other ideas for high-flying wind farming including a Dutch proposal to use pairs of kites to drive a generator."
Hope they tell the FAA before they put one up...
Somehow, putting up tons of windfarm hardware in the jetstream, strikes me as a great way to disrupt airtravel.
If we take the kinetic energy out of the wind and transform it into electrical energy, will this cause any problems? If we do so on a major scale?
Is it even possible for us to tap enough power from the jet stream (or other high altitude winds) to cause problems?
The SHPEGS project is an initiative to design and build a system that uses a combination of direct and indirect solar collection to generate electricity and store thermal energy in an economical, environmentally friendly, scalable, reliable, efficient and location independent manner using common construction materials.
I once had a similar idea: to pull energy right out of the air. Here's what I would do: separate a sealed chamber into two subchambers with a little door between them that could be opened. Have some kind of monitor determine *just* the right time to open it so as to increase the pressure in one side. When the pressure difference is large enough? Have one side expand against the other, drawing out useful work. End result? Both chambers have the same pressure *which is less than atmosopheric*! So to recharge, I just open it up to the atmosphere, and start over again.
:-/
Go, me, right?
After a few days of this, I woke up to find a severed horse's head in my bed. A note attached to it said. "You're depressurizing the atmosphere. Stop."
That settled it for me
Apology to Ubuntu forum.
Gather 3 wives and their mothers in front of these devices: output to be rated at MW/cup of coffee.
Take the 90-Day Challenge! http://rwmurker.bodybyvi.com/
"The Economist magazine has an article on Flying wind farms. Mind you, we're not talking about ordinary, terrestrial windmills here.
You're kidding? Flying wind farms aren't ordinary, terrestrial windmills? You learn something new every day!
There are shills on slashdot. Apparently, I'm one of them.
But what of Global Calming?
- Minutus cantorum, minutus balorum, minutus carborata descendum pantorum.
"Is it even possible for us to tap enough power from the jet stream (or other high altitude winds) to cause problems?"
No. The total power we could possibly harvest with systems like those in the article is not worth mentioning in the scale of the total energy in the jet stream. Windmills take a few percent of the energy of the wind that actually passes over them, wich would only be a tiny fraction of the wind in the jet stream.
You know what else tends to reside in the path of the jet stream? Storm systems.
I bet that these things would make excellent conductors for lightning. Take them down when storms approach and put them back up afterwards? Probably not feasible.
Then again, they would probably build up a heck of a static charge themselves just with the wind flowing over them.
Oh yeah, would ice build-up be a problem? Maybe not at the windmill itself, but on the tether, perhaps.
Seems to me there's a few (obvious) technical hurdles to address, first./p.
So don't RTFA (I haven't :) ), but make some estimate in your head of the total percent of the energy in the jet stream they could possibly harvest. I have some idea the scales involved and the efficiency of wind turbines, and in my wildest speculations I can't see how they are going to make even a tenth of a percent difference in the strenght of the stream. It's not going to be a problem.
Update: Just for kicks, I Read The Fine Article. In it, it is estimated that 1% of the power in the jet stream would power the entirety of human civilization. Not that you'd ever get that much, but again, not a problem.
The cable that is tethering it to the ground will be a hazard to aviation and all altitudes below the generator. Not only would the cable be very hard to see, but, unlike power cables and guy wires for antennas, it would also be hard to chart, since I imagine that the generator will move around quite a bit as the jetstream fluctuates.
You know, where airliners tend to like to fly
Don't worry, they've planned for this. Air cowboys are ready to rassle up those wild airliners and keep them out of harm's way.
Bitchslapped. Neat.
All 1.21 Jiggawatts of it!
It's a good thing it might be profitable, otherwise we would have to forget about the idea forever.
According to this public disclosure meeting in 2001, whereby high ranking government officials, very senior ex-military, black project staff, and ex-NASA employees pointed out... Zero point energy (aka. free energy) devices already exist, and have for decades, but are hidden by secret black project government programs due to the massive economic impact it would have on the world (i.e. no more need for OIL).
VIDEO: http://www.youtube.com/watch?v=uCLOIcFTSlE
It's time USA citizens wrote their congress men and appealed for all of these senior government etc officials to have a chance to testify under oath as they have promised to do. To date the disclosure project has over 400 such officials willing to testify. This is not wacko conspiracy theorists coming up with crazy theories... it's about the largest government cover up in the history of the modern world.
Adeptus.
PS. If the above is not enough to motivate you, think about how a world without burning fossil fuels would end the global warming impact nearly overnight! The evidence is simply overwhelming. See the video for yourself.
No trees were killed in the making of this post; however, many trillions of electrons were horribly inconvenienced.
You're right. We should stick to burning coal, firing gas, building dams, and fissioning radioactive materials. Those have all proven to have no unintended consequences.
I'd honestly be more concerned with global warming killing the jet stream than this. The jet stream is largely the result of low-altitude/surface-level thermal gradients (ie the equator to pole temperature difference). Given that most climate models predict the poles will warm significantly more than the equator, if they turn out to be correct I'd say that's far more troubling to the jet stream than a few big kites.
... what about the power transfer cable? I can't imagine a cable that can carry 10MW of juice over 10KM of distance could possibly considered a lightweight matter. This little helicopter contraption will need to generate power AND have enough energy to remain aloft under the weight of that cable. I think it's an interesting concept, but the solution to all our future power woes? Enh. While we're dreaming big, I'd be more interested in this Energy Island concept being built out.
Uh huh. Some guy named Gibbs had some. I learnt about it in college.
...the future crusty old bastards are already drinking the Kool-Aid.
Windmills take a few percent of the energy of the wind that actually passes over them, wich would only be a tiny fraction of the wind in the jet stream.
Even of the wind that actually passes through the area "swept" by the blades, the max it can harvest is about 59.3%. This is the "Betz Limit", the aerodynamic counterpart of the Laugher Curve of government revenue versus tax rates:
- Extracting power slows and deflects the air.
- Slowing and deflecting the air reduces the amount of moving air you can extract power from.
- Don't slow/deflect it and you get no power, stop it completely and you get no air - and thus no power. Zero at both ends, non-zero between. Somewhere there's a maximum.
- The maximum (for compressible fluids in free space) is where you extract 16/27ths of the energy from the air you affect (which is essentially the stream of air that passes through the area swept by the blades).
Real turbines can get very close to that, and most of the shortfall is a bit of energy left as rotation and turbulence in the wake.
Bantam Dominique roosters crow a four-note song. Once you've heard it as "Happy BIRTHday" you can't NOT hear it that way
What are chances that the geographical areas where these contraptions are installed get hit by bad weather (i.e. typhoons, tornados, hurricanes, hailstorms, lightning, etc)?
They're in the jet stream. That's up at the TOP of the troposphere. The turbulent violence you're talking about happens further down - the top mostly just has winds, and the jet stream is already the worst of it.
Assuming the power station comes down in any uncontrolled fashion, and from the heights they are talking about and the strong jet stream winds they are dealing with, the power generation station could potentially travel many miles before it hits ground, endangering a very very large area below.
Now that would depend on the type of elevated structure. But most of them have acceptable failure mechanisms.
For instance: The four-bladed "helicopter" should auto-gyro nicely. If it loses its tether the blades keep spinning and keep providing lift - in the correct direction even. By transferring power from one blade to another as needed you can navigate it like a glider - even upwind, trading altitude for blade momentum as you drop. This lets you fly it to a landing area, landing vertically and quite gently, even without any additional power source onboard. Or find an updraft and soar until any crummy weather at ground level has moved on.
Bantam Dominique roosters crow a four-note song. Once you've heard it as "Happy BIRTHday" you can't NOT hear it that way
"Perhaps you are neglecting the Butterfly Effect."
I am not. I have a degree in Mathematics in which I made a particular study of chaotic dynamical systems. I've written papers about the Butterfly effect; I've constructed physical models that demonstrate it. Let me tell you about the Butterfly Effect, so that you can refrain from bringing it up in discussions such as this in the future:
In a system which exhibits sensitive dependence on initial conditions (such as the weather), you cannot predict the details of long-term behavior (will there be a tornado in Iowa exactly 1 year from today) because tiny variations, well below what your measurement of the system could possibly account for (such as the breeze generated by the flapping of butterfly wings) will cause reality to drift further and further out of synch with your model until there is no resemblance on the detail level.
So the butterfly effect makes it impossible to ever predict what day it will rain months in advance, for example. But it does not prevent predictions about the aggregate, macroscopic behaviour of the system as a whole. In Meterological terms, long term weather prediction is impossible, but short-to-mid term climate prediction is easy.
Lets be ridiculously generous, and say this system takes a thousanth of a percent of the wind energy in the jet stream out. Is it reasonable to suppose this might cause significant changes in the world climate that will make a huge difference in its suitability for humans? No; it is not remotely reasonable. It's just not enough energy to make much difference.
Would it mean sometime in the future there will be a thunderstorm one day and not another? Absolutely. Whether you exhale the next breath you take slowly or forcefully means exactly the same thing; the minute difference in the velocity of a few thousand molecules of air your breathing pattern makes will eventually mean the difference in what day you get a thunderstorm.
The relevance of the Butterfly Effect in deciding whether to build this wind farm is the same as its relevance in deciding how forcefully to exhale your next breath. It means that the exact effect of either cannot be predicted, and that's it. It's not a reason to not do anything. (Well, except things like attempting long term prediction of weather detail.)
Hope that helps.
What you said about the Butterfly Effect is correct but deals with the impact of small random fluctuations on a chaotic system. In this situation the planned alteration is highly non-random (a consistent reduction in energy potential of the jetstream), and the inevitable consequence of success is a gradual and significant increase in the magnitude of the change. The Butterfly Effect is not the correct model for non-random state changes of increasing magnitude.
In other words, the quoted person is thinking about a valid concern, but used the wrong model to express it. The concern is still valid however. Will our actions disturb a delicate balance in nature of which we are not yet aware? We just don't know. Experiments of this scope are not the ones that you want to go the wrong way, so I sincerely hope that this company and the government spends as much time determining how to calculate the limit of what we allow ourselves to pull from the jetstream as we do figuring out how to do it.