Definitely a lot of considerations in this design. I think it's a pretty clever bit of engineering - however I'm willing to bet that between regulatory requirements, safety hazards and other usage issues (maintenance, lightning, etc.), that the road to market for this technology will be significantly higher than for other alternative energy approaches I've seen. It might even prove fatal for this approach . I think it's a brave vision nonetheless.
One thing that fascinates me about wind power its intrinsic multi-purpose impact.Like oil well fields, most of the ground is unoccupied by the wind turbines (but with much more power per tower than per well).Oil production, wind production, beef production*, grain production*, and wildlife habit*, may all occupy the same space. Additionally a wind tower or balloon may provide other services that such structures perform (elevation of communication tranceivers, cameras, and radar)
The aerostat turbines bring two additional factors to this: greater power density (if not greater efficiency) and transience. For all of the expense of building a tower, you have to repeat the expense if you need to move it – Tethered balloon turbines may be relocated seasonally, annually, or contingently in response to seasonal, climatic, or other variations in demand or wind.
*(Presuming complementary modern intensive grazing management and no-till practices)
So many of the FARs are interrelated. The 500' altitude limit on the balloon is probably there because that is the lowest cruising altitude over an uncongested area. In that way an aircraft can't possibly stumble into the balloon. The same goes for the 500' below any cloud restriction, which is the same restriction that VFR pilots fly by. I really think the only way to permit the balloons to fly higher, safely, would be to create a restricted airspace for them. With so much risk and so much cost, I'm not sure it's a better solution than a ground based windmill.
Surveillence radar and cameras have been regularly flying on balloons up to 15,000 feet (e.g., USAF Tethered Aerostat Radar System)
I seems to me that 14CFR Part 101 mostly defines what people can do with out FAA oversight (or ATC corrdination, flight cetificaiton, or licencing), e.g., defining what actions do not infringe on airspace.
re: "temporary", let's just call it a portable installation, but yes, I could see their design in use in a permanant installation.
cf., the proposed San Luis downdraft towers are around 3000ft.
I have a sneaking suspicion that this new innovative device will cause the FAA rules, as currently drafted, to consider some updating.Obviously, this type of craft was not in the thoughts of the authors at the time of its writing. Ah, Change is Good !
Thanks for that info, ironhorse. Since 14 CFR Part 101 gives over 500 feet as a limit, I wonder if this is the regulation (mentioned at the end of the press release) that was amended to increase height, or if another regulation that allows objects above 500 feet was amended to include balloons and wind turbines. I'm not sure what you mean in your last comment by "the temporary nature of the installation"? I don't believe these are designed to be temporary.
I had found some relevant FAA regulations last week. 14 CFR Part 101 covers such issues as model rocketry, kites, and balloons. Not very lengthy, but it seems that while the present discussion calls the application "tethered", the FAA calls it "moored" because it carries no intended passengers. As such, the FAA is mostly concerned about flight hazards or obstructions the balloons present. The "Barrage Balloon" concerns, again, are matters of generations of operational experience:
"Any balloon not designated to carry people is not regarded by FAA as an aircraft and is regulated under 14 CFR Part 101 only insofar as it might become a hazard or obstruction to flight. It must be more than six feet in diameter or have a gas capacity of more than 115 cubic feet, must be flown no higher than 500 feet above the ground and no less than 500 feet below the base of any cloud, must be flown no closer than five miles from the boundary of any airport, and must not be flown when the visibility is less than three miles. When operated between sunrise and sunset the balloon and its mooring lines must have colored pennants or streamers attached at 50 foot intervals beginning at 150 feet AGL and visible for at least one mile. When operated between sunset and sunrise the balloon and its mooring lines must be lighted to give a visual warning regardless of its altitude. To prevent runaway accidents, an automatic rapid deflation device must be attached so that it will activate if the mooring lines fail. This device must function independently from any crew or other human input."
Obviously, operating over 500 feet should involve FAA concern. I'm guessing, but owing to the temporary nature of the installation, operation over 500 feet I would think would involve normal channels of ATC NOTAMs "Notices To Airmen":
True, I have to agree with that "Pilot's Perspective" ,,,, Giant wind balloon in the sky – Easy to see, no problem.Giant wind balloon in the sky, 10,000's of feet over-head tethered by a fine, thin cable, sounds like a trip-wire hazard.Maybe they need to limited to 2,000 feet with a red-beacon cable (like on current radio aerial towers) for example-?
I really dislike the idea of a tethered balloon a few thousand feet in the sky. It's pretty easy to see the balloon and avoid it as another aircraft, but the tether would be another problem all together. Radio towers are stationary, well lit, and rarely exceed 1000' AGL. The article suggested "thousands of feet" of altitude, making for a difficult to see tether extending into the normal cruising altitude of of General Aviation aircraft. Imagine a balloon at 3000' with a ceiling of 2500' putting the balloon out of sight. You have VFR conditions and the only indication of a plane shredding barrage balloon in the area being the tether. It sounds darn scary to me.
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