Question:
I think the blimps would have to support the full weight otherwise when the wind dropped you wouldn’t need to winch the turbine in, it would just plummet. It might be difficult to keep the guys away from the blades, although the blades could be at the downwind end of the machine. I guess it would depend how it would behave in turbulence. I’d guess the foundation could be lighter and guys, shackles and even a winch must be cheaper than a concrete tower but what would the balloons and the gas cost? It would be more visually intrusive than a fan on a stick so there would be more objections from countryside walkers, but maybe they could be built offshore too. Malcolm – Hide quoted text — Show quoted text -> Wind turbines can vary their load by delivering less and less electricity; > thereby, adjusting air drag of the turbine. When equipped with variable > pitch propellers, the wind turbine could keep more or less constant air drag > from 10-200 K/H winds. This design keeps the drag on guy lines almost > constant. Under a good power wind, the turbogenerator would act somewhat > like a kite; therefore, blimps could lift one turbine and get it started, > followed by another and another–making a stack of three or four high when > wind conditions permit. As wind decreases, turbines must be lowered to the > ground. The blimps could then be lowered in event of a storm. All this can > be done via remote control over the internet. > >The Canadians are proposing that a Blimp and Guy Lines with smart wenches > >can hold a radio telescope receiver of 500 kg, virtually stationary at > 500 > >meters above the earth. Why not station a wind turbine and generator at > 250 > >ft; it must be held steady, but not to the tolerance of a radiotelescope. > >This provides an ideal position above the earth for lightweight permanent > >magnet direct drive turbo-generators. > FWIIW, there are already 200 foot towers that work, > you can see them in the latest issue of HP > Thern there is the issue of why go much higher than 200 feet. The > earth boundary layer is roughly the height of the surface terrain > features. > Once you get one or two boundary layers high, there is very little benefit > to going still higher. > Of scourse if you are talking 30 or 40 thousand feet up, then you get a > change, > but I suspect you’d pay for it in the cost of cable > –georges
Response:
Wind turbines can vary their load by delivering less and less electricity; thereby, adjusting air drag of the turbine. When equipped with variable pitch propellers, the wind turbine could keep more or less constant air drag from 10-200 K/H winds. This design keeps the drag on guy lines almost constant. Under a good power wind, the turbogenerator would act somewhat like a kite; therefore, blimps could lift one turbine and get it started, followed by another and another–making a stack of three or four high when wind conditions permit. As wind decreases, turbines must be lowered to the ground. The blimps could then be lowered in event of a storm. All this can be done via remote control over the internet.
– Hide quoted text — Show quoted text ->The Canadians are proposing that a Blimp and Guy Lines with smart wenches >can hold a radio telescope receiver of 500 kg, virtually stationary at 500 >meters above the earth. Why not station a wind turbine and generator at 250 >ft; it must be held steady, but not to the tolerance of a radiotelescope. >This provides an ideal position above the earth for lightweight permanent >magnet direct drive turbo-generators. > FWIIW, there are already 200 foot towers that work, > you can see them in the latest issue of HP > Thern there is the issue of why go much higher than 200 feet. The > earth boundary layer is roughly the height of the surface terrain features. > Once you get one or two boundary layers high, there is very little benefit > to going still higher. > Of scourse if you are talking 30 or 40 thousand feet up, then you get a change, > but I suspect you’d pay for it in the cost of cable > –georges
Response:
>The Canadians are proposing that a Blimp and Guy Lines with smart wenches >can hold a radio telescope receiver of 500 kg, virtually stationary at 500 >meters above the earth. Why not station a wind turbine and generator at 250 >ft; it must be held steady, but not to the tolerance of a radiotelescope. >This provides an ideal position above the earth for lightweight permanent >magnet direct drive turbo-generators.
FWIIW, there are already 200 foot towers that work, you can see them in the latest issue of HP Thern there is the issue of why go much higher than 200 feet. The earth boundary layer is roughly the height of the surface terrain features. Once you get one or two boundary layers high, there is very little benefit to going still higher. Of scourse if you are talking 30 or 40 thousand feet up, then you get a change, but I suspect you’d pay for it in the cost of cable –georges
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These are all very good points, including help refining the math model. I have one observation to contribute. The University of Calgary Radio Astronomy Laboratory faces all these issues, and their conclusion was a blimp. Was that decision made because a tower introduces aberrations in the received radio signal, or was it for economic reasons. I quote the University Web Page: "To realize a Square Kilometre Array at reasonable cost, a new means must be developed to construct very large apertures for radio telescopes at a small fraction of the cost of conventional technology. " http://www.ras.ucalgary.ca/SKA/ska_tech.shtml The two applications do not have identical requirements, which means wind power may not be practical while a radiotelescope is. Nonetheless, I have enjoyed the brainstorming.
– Hide quoted text — Show quoted text ->The Canadians are proposing that a Blimp and Guy Lines with smart wenches >can hold a radio telescope receiver of 500 kg, virtually stationary at 500 >meters above the earth. Why not station a wind turbine and generator at 250 >ft; it must be held steady, but not to the tolerance of a radiotelescope. >This provides an ideal position above the earth for lightweight permanent >magnet direct drive turbo-generators. > FWIIW, there are already 200 foot towers that work, > you can see them in the latest issue of HP > Thern there is the issue of why go much higher than 200 feet. The > earth boundary layer is roughly the height of the surface terrain features. > Once you get one or two boundary layers high, there is very little benefit > to going still higher. > Of scourse if you are talking 30 or 40 thousand feet up, then you get a change, > but I suspect you’d pay for it in the cost of cable > –georges
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You also need to consider how high you need to send the blimp and then the mass of the cable which will provide the grid connection /winch to get the blimp back to the ground. I think you’ll find its not cost effective as the mass of the wire starts to become a major load which is not present in a wind turbine on tower. Well, only 30 – 60 metres, rather than 500 – 5000 metres. The wire has to be self supporting, i.e. thickest at the top, i.e. all the mass is in the air. MalcolmX —
Response:
>…The cost of a tower is proportional to its height…
More likely the cube of the height. >…Blimps vary in cost with the surface area of the covering material. >As the mass of the covering doubles, the lift increases 10x.
Doubling the mass of a 1′ diameter blimp by making it 2^0.5 feet in diameter would increase the lift by about 2^1.5 = 2.83, no? Nick
Response:
- Hide quoted text — Show quoted text – >Some of the engineering trade-offs are cost of blimp and winches vs. the >cost of a tower. An approximate answer follows this argument. The mass in a >blimp is less than the mass in a tower, especially a skyscraper, and the >cost of a large item increases linearly with its mass at the minimum. For >example, blimp material may cost 100 per pound whereas tower material may >only be 10 per pound. Yet, the tower costs more if it is greater than ten >times as massive as a blimp. The cost of a tower is proportional to its >height, lets assume 10 /m per Kg supported mass. Thus a 100m tower >supporting 1Kg would cost 1000. Blimps vary in cost with the surface area >of the covering material. As the mass of the covering doubles, the lift >increases 10x. For example, doubling the size (and cost) of a blimp that >lifts 1Kg makes a blimp that lifts 10Kg. Thus, blimp costs rise less quickly >than tower costs. Thus, the blimp solution favors more massive windmill >turbo generators.
Well…. maybe, but these are all hypotheticals, all approximations. We have hard cost figures for towers, rather than speculating we need to see what size blimps we would need to lift, and what size cables and winches we would need to restrain a given weight and volume of turbine. These would have to withstand winds (not just gusts) up to 155 mph to equal the durability of modern turbine tower combinations. You are going to need a lot more gear than just "light" blimps. You will need some pretty big winches to haul that load out of the sky. Another problem is the turbulence you introduce into the airstream with all these blimps. The whole point of going higher is to reduce the effects of ground shear and turbulence induced by trees, buildings and landscape in general. You will end up muddying the water in an attempt to get a cleaner drink. Imagine a windfarm with tens or hundreds of these rigs. Still another consideration is the cost of O&M. With a tower you provide a conduit for maintainance personel to access the turbine. The tower itself requires minimal maintainance. With blimps and cables and winches you have made it harder to reach the turbine. To repair or maintain it you need to take it out of the sky. Any pilot will tell you the most dangerous part of flight is take-off and landing. The time it takes to do this is lost production time. You also have introduced a lot more equipment that needs a much higher level of maintainance than a tower, still more costs. >Both towers and blimps use guy wires that transmit side to side forces of >the wind to the ground.
Wrong. Modern wind turbine towers have no guy wires. Towers are not meant to absorb bending torsion of >the wind blowing against the turbine.
Yes they are. The turbine should turn a permanent >magnet direct drive high voltage DC generator. The current can be >transmitted via copper coated steel cable to the ground. Kevlar cables may >be used for the guy wires since they don’t conduct electricity. Of course, >there are recurring costs for blimps–the helium must be replaced and the >blimp must be maintained.
I still maintain that it will be much more expensive to build and maintain. Where I could see such a floating turbine arrangement as having potential would be achored to the sea floor in the midst of the gulf stream. Much denser fluid, lots and lots of watts! Windpower, over 14,300 Mw sold. Assuming a 20% Capacity factor, that’s over 30,670 1980 F-100 equivalents !! Regards , Tim O’Flaherty
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>If you can erect a skyscraper of over 110 stories, how hard can it be to >raise a tower that high?
How much do you want to spend? >Just a thought, does the windmill have to be >directly connected to the generator? Couldn’t you have something akin to >a driveshaft come down the tower to the generator at the base?
A right angle drive would do the trick if the tower could stand the torque. Otherwise slip rings are quite effective. >That >would lighten the load at top. Yeah and I know the drive shaft is going >to add more weight (but it would be distributed),
In the wrong place. >more complexity (at >the ability to build higher towers) and more expense (and more power potential).
Now is it cost effective? M. Simon Space-Time Productions http://www.spacetimepro.com Free CNC Machine Control Software Free Source Code Control the World From a Parallel Port
Response:
>If you can erect a skyscraper of over 110 stories, how hard can it be to >raise a tower that high? Just a thought, does the windmill have to be >directly connected to the generator? Couldn’t you have something akin to >a driveshaft come down the tower to the generator at the base? That >would lighten the load at top. Yeah and I know the drive shaft is going >to add more weight (but it would be distributed), more complexity (at >the ability to build higher towers) and more expense (and more power
potential). I agree that it can be done. Towers are raised in sections and I suppose there is a way to raise additional sections with what you already have erected. What I see as a limitation is simply the force of more wind, pressing on ever-increasing turbine sizes, on the end of ever-increasing long levers. So two questions stand out, how high is it possible to go with a turbine on a tower and is it worth the added cost? The drive shaft would go against the direction needed to reduce costs. The current trend is to variable speed generators that lack transmissions. Windpower, over 14,300 Mw sold. Assuming a 20% Capacity factor, that’s over 30,670 1980 F-100 equivalents !! Regards , Tim O’Flaherty
Response:
Some of the engineering trade-offs are cost of blimp and winches vs. the cost of a tower. An approximate answer follows this argument. The mass in a blimp is less than the mass in a tower, especially a skyscraper, and the cost of a large item increases linearly with its mass at the minimum. For example, blimp material may cost 100 per pound whereas tower material may only be 10 per pound. Yet, the tower costs more if it is greater than ten times as massive as a blimp. The cost of a tower is proportional to its height, lets assume 10 /m per Kg supported mass. Thus a 100m tower supporting 1Kg would cost 1000. Blimps vary in cost with the surface area of the covering material. As the mass of the covering doubles, the lift increases 10x. For example, doubling the size (and cost) of a blimp that lifts 1Kg makes a blimp that lifts 10Kg. Thus, blimp costs rise less quickly than tower costs. Thus, the blimp solution favors more massive windmill turbo generators. Both towers and blimps use guy wires that transmit side to side forces of the wind to the ground. Towers are not meant to absorb bending torsion of the wind blowing against the turbine. The turbine should turn a permanent magnet direct drive high voltage DC generator. The current can be transmitted via copper coated steel cable to the ground. Kevlar cables may be used for the guy wires since they don’t conduct electricity. Of course, there are recurring costs for blimps–the helium must be replaced and the blimp must be maintained.
– Hide quoted text — Show quoted text ->If you can erect a skyscraper of over 110 stories, how hard can it be to >raise a tower that high? Just a thought, does the windmill have to be >directly connected to the generator? Couldn’t you have something akin to >a driveshaft come down the tower to the generator at the base? That >would lighten the load at top. Yeah and I know the drive shaft is going >to add more weight (but it would be distributed), more complexity (at >the ability to build higher towers) and more expense (and more power > potential). > I agree that it can be done. Towers are raised in sections and I suppose > there is a way to raise additional sections with what you already have > erected. What I see as a limitation is simply the force of more wind, > pressing on ever-increasing turbine sizes, on the end of ever-increasing > long levers. > So two questions stand out, how high is it possible to go with a turbine on > a tower and is it worth the added cost? > The drive shaft would go against the direction needed to reduce costs. The > current trend is to variable speed generators that lack transmissions. > Windpower, over 14,300 Mw sold. > Assuming a 20% Capacity factor, > that’s over 30,670 1980 F-100 equivalents !! > Regards , Tim O’Flaherty
Response:
>How much higher can they go with a tower? At what point is it impractical >or unworkable?
The unworkable part will be the size of the crane necessary to erect them. As the generators get bigger and the tower sections get heavier and longer, the number of available cranes with the necessary weight/height capability shrinks, eventually to zero. It may be possible today to design a working multi-MW wind turbine that cannot be erected with any existing crane.
Response:
If you can erect a skyscraper of over 110 stories, how hard can it be to raise a tower that high? Just a thought, does the windmill have to be directly connected to the generator? Couldn’t you have something akin to a driveshaft come down the tower to the generator at the base? That would lighten the load at top. Yeah and I know the drive shaft is going to add more weight (but it would be distributed), more complexity (at the ability to build higher towers) and more expense (and more power potential). – Hide quoted text — Show quoted text ->How much higher can they go with a tower? At what point is it impractical >or unworkable? > The unworkable part will be the size of the crane necessary to erect them. As > the generators get bigger and the tower sections get heavier and longer, the > number of available cranes with the necessary weight/height capability shrinks, > eventually to zero. It may be possible today to design a working multi-MW wind > turbine that cannot be erected with any existing crane.
Response:
>I knew a smart wench once, but they are rare (D&R)
Did she keep your telescope high and your lines taut? –georges
Response:
>The Canadians are proposing that a Blimp and Guy Lines with smart wenches >can hold a radio telescope receiver of 500 kg, virtually stationary at 500 >meters above the earth. Why not station a wind turbine and generator at 250 >ft; it must be held steady, but not to the tolerance of a radiotelescope. >This provides an ideal position above the earth for lightweight permanent >magnet direct drive turbo-generators.
We already have towers past that at 80 meters. A Lot simpler and cheaper. How much higher can they go with a tower? At what point is it impractical or unworkable? I haven’t seen any discussion of that. >Some research should be done to learn if a parafoil, or other blimp shape >will accelerated the wind in the vicinity of the turbo-generator.
Some work has been done on Augmenter/Diffuser systems. http://www.vortecenergy.com/showcase/introduction.asp It looks like a lot of extra gear, more comlicated and expensive. I think the original form is hard to beat. Windpower, over 14,300 Mw sold. Assuming a 20% Capacity factor, that’s over 30,670 1980 F-100 equivalents !! Regards , Tim O’Flaherty
Response:
Spelling checkers aren’t perfect. I stand corrected, smart winch.
– Hide quoted text — Show quoted text -> I knew a smart wench once, but they are rare (D&R) > — > — > Steve Spence > Subscribe to the Renewable Energy Newsletter: > http://www.webconx.com/subscribe.htm > Renewable Energy Pages – http://www.webconx.com > Palm Pilot Pages – http://www.webconx.com/palm > X10 Home Automation – http://www.webconx.com/x10 > (212) 894-3704 x3154 – voicemail/fax > We do not inherit the earth from our ancestors, > we borrow it from our children. > — > The Canadians are proposing that a Blimp and Guy Lines with smart wenches > can hold a radio telescope receiver of 500 kg, virtually stationary at 500 > meters above the earth. Why not station a wind turbine and generator at > 250 > ft; it must be held steady, but not to the tolerance of a radiotelescope. > This provides an ideal position above the earth for lightweight permanent > magnet direct drive turbo-generators. > Some research should be done to learn if a parafoil, or other blimp shape > will accelerated the wind in the vicinity of the turbo-generator. > Edwin Earl Ross
Response:
I knew a smart wench once, but they are rare (D&R) — — Steve Spence Subscribe to the Renewable Energy Newsletter: http://www.webconx.com/subscribe.htm Renewable Energy Pages – http://www.webconx.com Palm Pilot Pages – http://www.webconx.com/palm X10 Home Automation – http://www.webconx.com/x10 (212) 894-3704 x3154 – voicemail/fax We do not inherit the earth from our ancestors, we borrow it from our children. — – Hide quoted text — Show quoted text -> The Canadians are proposing that a Blimp and Guy Lines with smart wenches > can hold a radio telescope receiver of 500 kg, virtually stationary at 500 > meters above the earth. Why not station a wind turbine and generator at 250 > ft; it must be held steady, but not to the tolerance of a radiotelescope. > This provides an ideal position above the earth for lightweight permanent > magnet direct drive turbo-generators. > Some research should be done to learn if a parafoil, or other blimp shape > will accelerated the wind in the vicinity of the turbo-generator. > Edwin Earl Ross
Response:
The Canadians are proposing that a Blimp and Guy Lines with smart wenches can hold a radio telescope receiver of 500 kg, virtually stationary at 500 meters above the earth. Why not station a wind turbine and generator at 250 ft; it must be held steady, but not to the tolerance of a radiotelescope. This provides an ideal position above the earth for lightweight permanent magnet direct drive turbo-generators. Some research should be done to learn if a parafoil, or other blimp shape will accelerated the wind in the vicinity of the turbo-generator. Edwin Earl Ross
Response:
Mark M a r k T h o r n t o n The Franklin Company Consultants (TFC) Ltd. Bournville, Birmingham, United Kingdom Tel: +44 121 459 4826 Fax: +44 121 459 8206 WWW: http://www.demon.co.uk/tfc 
Mark M a r k T h o r n t o n The Franklin Company Consultants (TFC) Ltd. Bournville, Birmingham, United Kingdom Tel: +44 121 459 4826 Fax: +44 121 459 8206 WWW: http://www.demon.co.uk/tfc 