米兰理工大学的工程师Lorenzo Fagiano说，机载系统具有一些关键优势。Airborne Wind Europe, founded in 2019. In some countries, suitable land for wind farms is getting slim: Wind farms typically need a whopping 71 acres to generate a megawatt, compared to 12 acres for a fossil fuel plant, and the ideal locations will eventually run out. “The first farms are in the best spots, and the best spots are limited,” says Cristina Archer, director of the风力研究中心（船员）在特拉华大学。

In general, the higher you go, the faster the wind. “For a two-fold increase in windspeed, that’s eight times the power,” says Fagiano. An airborne system can reach up to 800 meters high (half a mile), far above the 200- to 300-meter tip of the tallest wind turbines. Thetheoretical global limit of wind powerat high altitude has been estimated to be about 4.5 times greater than what could be harvested at ground level.

It’s relatively cheap and easy to bring a wing to a remote location, adds Fagiano; these systems come in a container and can be dropped off wherever there’s a road or dock. They can also be tethered to an anchored barge in deep waters, where a traditional wind turbine cannot stand firm. Their height is adaptable, so they can be moved up or down to wherever the wind blows the hardest, which often changes with the seasons. “It’s such a good idea,” agrees Archer. “The attraction is its simplicity in terms of materials and costs.”

“It’s not going to replace conventional wind,” adds Archer. But advocates envision wind farms hosting hundreds of kites floating on barges in deep waters far offshore, while single wings—or smaller arrays—could unfurl to help power remote islands, temporary military installations, or mining operations in the mountains.

These ideas have been around for decades, but the path to using kites, wings, or drones to capture wind energy has been bumpy. In 2020, for example, an airborne wind energy company acquired by Google famously folded operations after engineers couldn’t make their system work economically. But others pursuing lighter, simpler versions of the technology, like SkySails, are now going commercial. A 2021 U.S. Department of Energyreport to Congress得出结论，这个想法具有很大的潜力，空中系统可能能够收获与美国与地面风系统相同的能源级数量级an important part of the nation’s energy solution.

最初被视为船舶的帮助

SkySails actually started back in 2001 with a different purpose: building soft kite wings to pull ships along at sea. The shipping industry has traditionally relied on a crude, dirty fossil fuel calledbunker fuel,他们的想法是,一个翅膀,喜欢the sails of old, help to dramatically reduce a ship’s fuel requirements. It was a concept ahead of its time. SkySails expected oil prices to keep rising, making their product more attractive. Instead, oil prices crashed in 2009 (and again in 2014 and 2020). Now, with more stringent requirements from the UN’s International Maritime Organization for减少排放的船只, other companies, including aspin-off from Airbus，正在拖船拖船。但是早在2015年，摩索艇就将重点转移到用摩托车发电的发电上。

Their system—likeseveral others under development- 在大约150平方米的，类似降落伞的机翼上，骑着风。空气中没有涡轮机，系绳不是电线。取而代之的是，能量是从线上的拖船上生成的。Fagiano说：“绞车的突破正在产生电力。”软件以图形模式自动驾驶风筝，以获得产生能量的最强拉力。然后该系统更改机翼的飞行模式，以便可以用最小的电阻将其拉入，从而消耗一点能量以将其吹回去。这种模式重复，产生的能量远远超过消耗的能量。

听起来很简单，发电系统是非常标准的。但是，摩西尾巴的首席技术官斯蒂芬·布拉贝克（Stephan Brabeck）表示，该团队花了大约七年的时间才能完善飞行软件，尤其是机翼可以安全地降落并自动发射。布拉贝克说，他们现在制造并卖出了五个单元毛里求斯the first to get up and running. They reckon that the wing will have to land some 14 times a year because of heavy rain, unsuitable winds, or thunderstorms. Occasional hurricanes, which an airborne system can weather tucked away on ground, is what makes the island unsuitable for traditional wind turbines, says Brabeck, an aerospace engineer.

The sails are less intrusive on the skyline than traditional turbines and quieter too, says Brabeck. And they make economic sense, he says, for anyone currently paying more than 30 cents per kilowatt hour from diesel generators. But there are challenges. Wind turbines can kill or wound migrating birds, and how birds will react to these kites “hasn’t yet been very well studied,” says Fagiano. SkySails has studies underway. The tether on any such system, notes Archer, could theoretically trip up drones or even small aircraft. And if a tether breaks or guidance system fails, a system can crash to the ground.

That might not be a big deal for a soft wing, but other companies are pursuing rigid wings more like a hang glider than a paraglider. These can be more efficient and have better control, but crashes can be a bigger issue, making them a better bet for offshore use. “Essentially, they are aircraft,” says Fagiano. “They will have to reach a level of reliability close to civil airplanes.”

More ambitious plans ahead

A third, more ambitious option is to make a hard-winged drone that has heavy wind turbines and generators on board and sends the electricity down the tether. This option would produce more consistent energy (without needing to cycle between energy production and energy expenditure), but it’s a hard nut to crack.

Fagiano说：“我们谈论的是一项具有很多方面的完全新颖的技术。”“新涡轮机。新的一切。”Google早在2013年就拿起了一个由Makani Technologies领导的一个这样的项目。他们进行了一些成功的测试，但经济学并没有加在一起，在2020年，Makani项目折叠。Google发行了一部有关这种体验的YouTube电影，并免费获得了Makani的所有研发和专利。

Plenty of other companies are now in the race to pick up where Google left off, or to find a better solution. This includes Netherlands-based风筝能力，该项目在加勒比海地区和挪威Kitemill，目的是制造兆瓦规模的系统。其他人甚至正在设计类似的系统，这些系统在相同的原则下工作，但是underwaterinstead of up in the air, using ocean currents instead of wind to drive a submarine glider in a figure-eight. SkySails plans to test the concept of an airborne wind farm in the American Midwest before they move offshore. “You need a lot of space,” says Brabeck.

As commercial activity ramps up, says Fagiano, one of the biggest hurdles is regulatory: Airspace rules aren’t designed to accommodate these wings. “It’s chicken and egg,” he says. “So long as there aren’t technologies, they don’t make regulations. Without regulations, it’s hard for companies to raise money.”

With the first commercial pilot products now out there, “in remote locations, the costs are already pretty competitive,” says Fagiano. If airborne wind systems start to be mass produced, he says, there’s no question they’ll produce affordable energy. “The question,” he says, “is whether we ever reach mass production.

Nicola Jones is a freelance journalist in Pemberton, British Columbia, with a background in chemistry and oceanography.