Why go through all the effort? Aren’t current surface-based wind turbines pretty good?
This is a very important question. Pardon our long-winded answer (and the pun). At the most desirable surface wind power generation sites*, the wind contains 400-1000 watts per square meter (w/m2). The wind at 10,000 meters (35,000 feet) is one-third as dense and blows five or more times as fast, which means that it carries 10,000 – 40,000 w/m2. High-altitude wind has 30 times more power density than surface wind. This is because of two factors: First, the power in the wind decreases linearly with decreasing air density, so air that is one-third as dense contains one-third the power. Second, the power contained in the wind increases as the cube of speed, so five times the wind speed yields 125 times the power. Equally, if not more important is that high-altitude wind is significantly more consistent than surface winds. Even during times of low wind, our system can tack across the sky on the tether, thus maintaining consistent output.
