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I am interested in what has been done to study no-moving-parts wind power extraction. Alvin Marks (who beat out Edwin Land for the polarized-sunglasses patent) filed a patent on this back in the '80s. The idea is simple: you ionize air moving through your system, and the wind carries the ions away, accumulating a grid voltage vs. ground. The restoring current can do work. If your screen is on a kite, it can be very high up, to catch very high wind speed. It is very cheap to construct, with no mechanical parts at all; restoring current runs up (strictly speaking, down) the kitestring. Or, a screen could be stretched between upper parts of pairs of existing skyscrapers, or towers of a bridge, almost invisibly. The trick is how to ionize air cheaply. Certain materials give up electrons to moving air spontaneously; you could have streamers of such materials, modified to be slightly conductive. Otherwise, you need some sort of charge pump to favor losing surface charge. Maybe a mist of water carries away the ions. Measures of efficiency can be confusing. Ultimately, the measure that matters is W/$. If the installation is cheap enough to build and operate, percentage of available wind power extracted may be almost irrelevant. Stretched between existing structures, you might not want to extract much of the available energy anyway, because of the load it would place on the structure. But the next screen downwind could extract as much power, again. |