Intriguing implementations of wind power
Bill Schweber - February 5, 2013
You’re certainly aware of wind power as an credible energy source, and have seen those big towers with their slowly rotating blades. (I have conflicted feelings about these towers and also about wind as a viable source of large amounts of consistent power, but that’s a discussion for another day.)
However, I recently saw two stories about very different approaches to wind power - one very large and the other fairly small - that were certainly interesting.
The first, "The Benefits of Airborne Wind Energy" in IEEE Spectrum, looked at using kites for wind power. I had read snippets about this emerging technology, but never really looked into it.
First thing to know is that these are not kites as most people think of them. They are sophisticated semi-rigid and rigid airfoils and structures. The presumed virtue of the kite approach versus a fixed tower is that the kite can be higher, where the winds are stronger and more consistent, while the set-up is relatively quick and the physical siting is flexible.
I was under the misconception that the kite-power design was like a tower-mounted approach, except that the blades and generator were linked to the ground by a cable carrying the power, and which also tethers the kite. That seems to me like a tough design challenge, since the cable would have to be fairly hefty (weight and thickness) to be a low-loss kW conduit handling hundreds of amps and thousands of volts.
It turns out that while that is indeed one approach being tried, the article really focuses on another, where the kite - under some sort of automated tethering and control - flies back-and-forth and thus winds/unwinds a drum in ground-based unit. This drum, in turn, is connected to the generator, also ground based.
Is this practical? I don’t know. Certainly, there are lots of technical problems with each part of the system that need to be addressed and solved. Maybe this will work out, maybe not. Or maybe it’s a good solution for very specific niches, where lots of power is needed on short notice, perhaps just for a limited time or in a remote location.
The other wind-power story I saw is at the other end of the power-level spectrum. It was a brief story about a company, Wing Power Energy, which is developing mini-wind generators specifically designed to be installed on cell towers, to provide power for that tower alone, “Wing Power Energy focuses on micro-wind systems for cell towers, buildings.” (Many towers now use solar power for primary or backup power.)
When I saw this article, my immediate reaction was “hey, that’s a good idea, why hasn’t it been done before?” It makes a lot of sense to me: it’s a bounded, well-defined application with a known load, and you already have the tower available.
Is there a technical reason it has taken so long for this to bubble up? Maybe there's a technical shortcoming or cost/benefit/ROI issue I don’t see? Plus, if the idea catches on, it could also reduce the cost of similar home-based installations, too, for backup and perhaps even primary power (though there is still the issue of the tower, of course).
Are they other potential technical advances which caused you to wonder why it wasn't done earlier? Did you subsequently find out that there were non-obvious obstacles that made practical implementation much harder than you casually assumed it would be?