Am I missing something? How could the generator car possibly "loop back" when the kites are pulling in a vector that probably won't vary by more than 45 degrees? Assuming a long narrow oval track at 90 degrees to the wind, on the straight legs of the oval the kites would only be providing a portion of the total force anyway: moving the generator first to the left, say, on the up wind straight leg, then following the wind direction through the first curve, then the kite would have to tack to the right, pulling the generator to the right on the downwind straight leg, then it would get to the next curve, somehow proceed against the kite force and midway through the curve the kite needs to reverse tack to the left, the generator still working against the kite to get back to the straight leg. If this works they've discovered perpetual motion.
Unlike solar farms or windmills which are inherently difficult to look at or follow with the eyes, advertisers could use these kites to place their logos on truly unobstructed billboards, and not cut down any trees in the process. So capitalism could serve environmentalism for a change. And vice versus.
Of course, the kites would have to fly in a public area, but those are the small details. : )
A close view of the picture shows four lines going to the kite. This might imply that that 4 lines are needed for strength and or redundancy. However, it also implies that the kite would be capable of being directionally controlled (tacking) allowing it to fly in directions not directly downwind. Nothing mandates that a track mounted generator can't store enough power to propel itself while tacking crosswind down a track perpendicular to the wind for the brief period needed to navigate the half loop at the end of an oval track. Then there's the design study needed to show if a figure 8 track (allowing more downwind travel) of a given distance would provide more net power than an oval track with a given diameter at the ends.
I think the only solution for aircraft concerns would be to ban aircraft from the area entirely. This is especially true since in the US, aviation is moving away from flight paths to routes decided by pilots through GPS tracking.
This is not unprecedented. There are many areas off limits to aircraft already.
It does remind me a bit of barrage balloons during Word War II I read about.
Excellent points about aircraft concerns. Lights could be one option; however, I'm sure as this system continues to get tested this will be addressed. One easy solution would be to try to put them in areas where there aren't often low-flying craft. Staying far away from airports is an obvious solution to that.
I didn't want to say anything from an aviation standpoint, because that's something I'm a little biased on. Since the door's been opened, I think it's outrageously dangerous to have a kite above 1000' AGL. Yes, there are antennas that reach that high with nice, bright beacons, and one can assume that the kite would be as well lit, but the problem with a kite is that you have no way of knowing where the aluminum shredding tether is going to be. There was a story similar to this before, and I likened the tethered, airborne windmill to a WWII era barrage balloon, and certainly, the effect to a passing aircraft would be similar.
I wonder if they've thought about potential aircraft collisions. In Illinois, where I live, it's very easy to spot wind turbines at night because wind farms typically have synchronized red lights that blink on and off at night. Could they do the same with kites?
Liz, thanks for covering this--what fun, how elegant, and I like the lower environmental impact of the technology. While most wind turbines don't go as high, the one we wrote about here http://www.designnews.com/document.asp?doc_id=243636 is designed to eventually achieve over 1,000 feet in altitude.
It might be very similiar to model rocketry protocol - waivers sometimes have to be filed and approved with the FAA and flight patterns have to meet certain criteria. That would probably be a good way to deal with air traffic. We wouldn't want a model rocket crashing through one of those kites!
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