George Douglas, a spokesman for the U.S. National Renewable Energy Laboratory, said, "We're now largely focused on only projects that can be commercialized quickly, such as those that can be brought to market in about 10 years." Startups such as KiteGen, Sky Windpower, Magenn and Makani began dabbling in high-altitude wind development a few years ago, and now it looks like they're on track to meet their goals ahead of schedule. Christina said, "We're not as far away from a working prototype as we thought." At the same time, however, she noted that the companies are invariably tight-lipped about their experimental data.
Barry Monette, Magenn's CFO, said the company will sell "two to four" working prototypes next year, at which point "the first revenue" will be credited to the company's account. Magenn's machines can operate at lower altitudes. We do think we're going to be the first to market, barring any surprises," Monett said."
In the long run, powering an entire city with such machines will remain difficult, in large part because, even with an optimal altitude location, there will be times 5 percent of the year when the wind doesn't blow. That means you either have to have backup energy, a large reserve of energy, or you have to have an entire continental or even global grid to keep the wind power available," said Ken Caldera, an ecologist at Stanford University who co-authored Christina's paper. So while high-altitude wind has the potential to ultimately prove to be an important source of energy, it requires sound infrastructure."