How Kites Could Transform Global Energy Forever

This kite isn’t just soaring gracefully … it’s also generating energy from the wind. If you’re like me, you’re probably thinking: “Neat, but don’t we already have an effective and reliable way to capture wind energy?” And yeah, wind turbines have been been big ol’ work horses for decades. But that’s part of the problem. Wind turbines are both physically and financially massive. Each one costs a minimum of hundreds thousand of dollars, and that’s before we take into account shipping, installation, and maintenance.

Goofy as it might sound, airborne wind energy systems (AWES) like this kite could be a cheaper, more nimble alternative to the steel titans we’re used to. But are AWES really ready for takeoff, or are they grounded for good?

This is Kitepower’s AWES, flying high above the town of Bangor Erris, Ireland.¹ AWES are a type of wind energy device that uses kites (and similar flying objects) to sustainably generate energy from the wind at a fraction of a turbine’s price. They’re small enough to travel, with most designs able to fit in a standard shipping container. You don’t need a massive construction team or foundation to install them. And on top of all that, most can be fully deployed in less than 24 hours.²

Kitepower’s maiden voyage, a first-of-its-kind test, proved successful when it provided the small community in Bangor Erris with energy. It was even able to supply energy in spite of the massive Storm Éowyn that rolled through the region causing devastating black outs.³

Most interestingly, AWES are able to soar high above other wind-based energy generators and access powerful, but untapped, airstreams. Generally, the higher up you go, the stronger and steadier the winds are. A 2013 study on the geophysical limits of wind power suggested that wind turbines located on Earth’s surface can harness kinetic energy at a rate of at least 400 terawatts (TW), while high-altitude wind power devices have the potential to capture over 1,800 TW.⁴

The Problem

To truly understand why some companies are leaving turbines to go fly a kite, let’s take a look at where wind turbines are lacking. But don’t get your line twisted: wind turbines are really good at what they do. They don’t require all that much land and can be installed without significantly disrupting farming activities. I’ve actually seen an energy company pull this off in person, which you can check out in a previous video.⁵ Plus, turbines offer low operating costs with components lasting more than 25 years.¹ That’s a pretty pleasing package as is.

So, where is that room for improvement? Well, there’s a whale of a problem…in the sense that wind turbines are really, really big. Your typical turbine is a little over 103 meters (or 339 feet) tall. That’s taller than the Statue of Liberty! But they get even bigger than that. In 2023, the average diameter of newly installed turbine rotors was over 133 meters (438 feet). That’s longer than a football field.⁶ As you can imagine, the sheer size makes transporting these parts notoriously difficult and expensive.⁷

To make sure that a large investment in wind turbines pays off, we need to set them up in the best conditions. Ideally, they prefer annual average wind speeds of at least 9 miles per hour, smooth rounded hills, open plains, or the sea. If you can place them near features like mountain passes that funnel and intensify the wind, even better. That’s a lot, but clearly not insur”mount”able.⁸

But even when you’ve snatched up the perfect parcel for your turbines, there’s still another hurdle: the neighbors. Not everyone is a big fan of big fans.⁹ Plenty of people are totally in favor of wind power…as long as it’s in your backyard and not theirs. As a result, wind farms often end up far away from the cities that need them most. Because energy is lost in transmission, it’s not as ideal as it could be.

The AWES Solution

That takes us back to AWES, an umbrella term that covers a lot of different working principles. For the airborne component, you’ve got everything from kites to balloons to the hybrids known as kytoons…as in “kite balloons.” Yes, that’s what they’re actually called. Some AWES work aerostatically, relying on something naturally floaty, like a balloon, to support the power generating elements.¹⁰ The aerodynamic variety are usually kites that fly in crosswind patterns to maximize wind pressure. These systems can adjust their altitude and trajectory to optimize wind conditions, or even smart launch and dock themselves if the winds get a little rowdy. Though having a trained operator is usually the way to go.¹⁰

Why bother going through all that?

Well, the lack of a tower means you can fly to the altitude where the wind is best on any given day. This freedom lets AWES access wind streams that towers just can’t reach. AWES can soar up to 800 meters, and here’s where it gets interesting: generally, the higher you go, the faster the wind. The mechanics mean that as little as a two-fold increase in wind speed could lead to 8 times the power generation.¹¹

According to a study from Lawrence Livermore National Laboratory and the Carnegie Institution, the theoretical global limit of wind power at high altitude is about 4.5 times greater than what could be harvested by turbines stuck closer to the surface.¹² Plus, because turbines and AWES aren’t competing for the same wind resources, they could actually complement each other. And unlike turbines stuck at one height, a kite gives operators the flexibility to move to wherever the winds are most favorable.

For my money, though, what really separates AWES from turbines is their portability. Most of these systems fit inside a single shipping container and can go anywhere a truck can.¹³ No foundation needed and setup in under 24 hours. This lets AWES pinch hit in situations where a turbine would be ridiculous: remote research outposts, hospitals in regions prone to blackouts, or rapid disaster response.

All these advantages translate into a promising levelized cost of energy (LCOE), at least in theory. This metric compares lifetime energy generation against installation and operational costs.¹⁴ By this measure, AWES look very promising. A 2023 Delft University study estimated that a 50 MW kite farm would use 70% less material than a traditional wind farm of the same capacity over 20 years.¹⁵

All these perks might have you wondering… if AWES are cost-effective and cool, then where the heck are they? Well, the technology is still in its infancy, but there are some early success stories to dive into.

Kitepower

Let’s return to Kitepower and its AWES flying high above Bangor Erris, Ireland. This is a Dutch company spun out of Delft University by astronaut Wubbo Ockels. Its first proof of concept came about in 2007, and now its team is close to commercializing their tech.¹⁶

Kitepower’s AWES is of the aerodynamic variety. It has a fiberglass skeleton undergirding an 60 square meters inflatable wing. It generates energy by working kind of like a big yo-yo. The kite spools up, up and away, 400 meters (around 1,300 feet) away.¹⁷ It flies upwards into the crosswind in that figure-eight pattern.¹⁸ This pulls the tether wound around a drum safely on the ground, spinning it up. Still, by doing this, the kite can generate between 2.5 and 4 tons of force, rotating that drum at high speed and generating up to 30 kilowatts of electricity per hour.¹

After 45 seconds, the kite reaches its maximum height, and tacks like a ship so that the push of the wind is minimized. Then it’s winched back in, rewinding the yo-yo for the next go. This is actually a pretty important step because reeling the kite back in costs energy. The less energy we spend fighting the wind, the more energy we gross.¹ And speaking of energy, its all stored in a 336-kilowatt-hour battery.¹⁷ That’s both nice for energy storage and potentially critical for the kind of off-grid or emergency situations that AWES seem especially well suited to.⁴

Kitepower isn’t resting on its laurels, though. The company has another test coming up, this time with a commercial partner on their home turf in the Netherlands. A construction company is planning to use the kite to charge electric trucks and excavators in a civil infrastructure project.¹

SkySails

Kitepower isn’t alone. On July 1st, Germany-based SkySails launched the maiden flight of its AWES, at Taipower’s Changbin Photovoltaic Field. It uses the same yo-yo principle as Kitepower’s system, but with some notable differences in scale.¹⁹²⁰²¹

They have a larger model called Kyo, that depending on wind conditions, will be able to generate up to 1,780 MWh of clean energy per year which SkySails claims is enough electricity for 600 households.²² There’s also an even larger system in the works, with an alleged annual yield of 6,580 MWh, and a cycle power of up to 1,300 kW.²²

SkySails also has some pretty creative ideas on how and where to deploy its tech. For starters, the company seems very into hybridizing its device by putting it to work right next to other renewables, like on solar farms and wind farms.

The team is also exploring the potential of attaching its system to the back of large watercraft like container ships. The idea is that its S-Class AWES would capture energy from seaborne winds and funnel it back into the ship to reduce fuel consumption.²³ An AWES could definitely be a welcome addition to the crew, considering that large ships often run on some of the foulest and most polluting hydrocarbons available…so-called bunker fuel.²⁴

Makani

Kitepower and SkySails are more recent examples, but AWES have been rising to the top some time now. Right around the time that Wubbo Ockels and Delft were founding Kitepower, Saul Griffith, Don Montague, and Corwin Hardham were working on their own AWES. Dubbed Makani, the Hawaiian word for wind, it involved a rigid wing with on-board turbines and generators. The wing flies in vertical circles and sends the generated power back down a cable to the ground. That’s notably different from the aerodynamic yoinking of other AWES we’ve talked about today.²⁵

Makani ended up being lucky enough to catch the eye of Google as part of its Renewable Energy Cheaper Than Coal initiative.²⁵ In May 2013, Makani Power was acquired by Google and was folded into Google X. Tragically, Hardham wasn’t around to see this, as he had died a few months prior. Despite his unexpected passing, it seemed like things were looking up. By December of 2016, the company’s 600 kW prototype with 28 meter wing span tested well. And an even larger, Boeing-747-sized, 5 MW monster was in the works.²⁶

In 2019, Makani was bounced from Google X to Google Alphabet, but things were still flying high with a minor investment from Royal Dutch Shell. That is…at least until the tests when Makani started to struggle. The system was having real difficulties making it back to its offshore launch platform, and it ended up crashed into the sea. Soon after, Google shrugged and grounded the kites, stating that commercialization process was just too long, complicated, and fraught.²⁷

Looking back, Google and other experts seem to agree that Makani was just too complicated, with too many possible points of failure. Ideal deployment locations were more limited than they first thought. Plus, there were unanswered concerns about how the AWES, specifically its long, nearly-invisible, fast-moving tether, would affect bird populations. These are all things to bear in mind as we look at the slightly simpler AWES designs that are trying to take off today.²⁸

But there is somewhat of happy end to this story. Before the company folded, it released the Makani Collection, an archive of open source code repositories, reports, flight logs and technical videos from the project. The team even made a non-assertion pledge on their patent portfolio, allowing anyone to use its patents without fear of legal reprisal.²⁹ Maybe one day the Makani Collection will be the wind beneath another AWES company’s wings.

Drawbacks

Sadly, it’s not all smooth sailing. Despite the promise of AWES, the technology is still too young to be topflight, and there’s a lot of issues that need to be addressed. As a study from the National Renewable Energy Lab (NREL) and the DOE points out, this newness means that everything from design, to manufacture, supply chain, logistics, installation, operations, and even maintenance still needs to be nailed down.³⁰

There’s also question of longevity.³¹ Wind turbines have a fairly simple working principle that comes with standardized components rated to last 20+ years. But with all their figure-eights and yo-yoing, a major question for AWES is how the lifespans and complexity of their components and accessory equipment stack up to their peers. And the answer to that question is going to have a major effect on AWES’ much-touted LCOE.

Then there’s safety. These types of kites are large and heavy, so a stalled one can be quite dangerous. And between midair collisions, the kite slipping its tether, and extreme weather events, there’s a lot that can wrong.³¹ To be fair, the fact that Kitepower’s test run survived Storm Éowyn and kept producing power before, during and after a record-breaking cyclone is cause to be optimistic on this front.¹⁷ But how many Éowyns it can survive? The Witch King of Angmar couldn’t even handle one! The hope, however, is that smart systems can circumvent this problem.

At the end of the day, the biggest issue that these systems have is that they simply don’t match up the the power generation of traditional turbines. An average turbine would generate over 843 MWh per month. According to the United States Geological Survey, that’s enough for more than 940 U.S. homes.³² That would be 10,116 MWh a year, far outpacing 1,780 MWh annual yield of something like the Kyo.²¹ Of course, comparing one AWES to one turbine isn’t very fair. We’d need several AWES flying in synchronized pattern to match up to turbine, though that’s going to complicate the economic and safety concerns even more.

Where does that leave AWES? Well, despite the challenges, the outlook is pretty positive. Again, I want to underscore the fact that the tech is in its infancy, with Kitepower running its early (but seemingly successful) test in Ireland, and SkySails’ maiden flight in Taiwan. We’re probably looking at a technological readiness level of 6, that’s a fully functional prototype or representational model. That said, with the early tests going well, we could be on the cusp of TRL 7.³³

While it seems like it’ll be years before AWES can compete with turbines, if ever, I still think they already have a unique and well defined niche. The fact that they access so those extra high-up, high-powered wind streams that no one else can is cause for excitement. They also have the opportunity to fill in gaps in rapid response and emergency, and we’ll see what other weird applications pop up, like SkySails’ back-of-the-boat proposal.