Airborne Wind Turbines_ The Future of Clean Energy

Airborne wind energy systems are pretty awesome. They're wind turbines, but without towers. By flying at higher altitudes, they can harness strong and reliable wind. It's a fascinating concept. Some say crazy. There's been a lot of failure over the decades and few viable systems. But the dream of accessing better wind conditions with less materials than traditional wind turbines is very much alive. There are claims that airborne wind could deliver super cheap electricity with around half the carbon footprint of traditional wind turbines. But do these numbers add up? How practical are these designs? And what about the birds? So will these next generation systems bring a wind energy revolution, or will their inherent complexity and instability stop them from ever taking off? I'm Ryan Innes, and this is a Xeroth Deep Dive. I'd also like to point out that I went to a special effort to get wind turbines in the background, and they are completely covered in clouds. A great description of airborne wind energy is a turbine stripped back to its power generating essence. With no towers, no foundations, and no massive aerofoils, these high-flying wind power converters operate in wind gradients turbines can only aspire to. Higher altitudes have stronger wind because there's no friction or drag from the Earth's surface. And there are no hills, buildings, or trees in the way. With higher wind speeds, the wind energy available increases as you get higher up. And although it varies by location and atmospheric conditions, it's safe to say that if a turbine could go higher than the current record of 280m or so, they could produce more power. Airborne wind energy systems, on the other hand, can reach up to 800m. And even if plans to build a 365m turbine come to fruition, it couldn't rival the efficiency of a lightweight kite because of the material and infrastructure required. That's all very well in theory, but how do these flying turbines actually work? There are loads of designs floating around, but they generally come into two broad categories depending on where the electricity is generated. The first category is called flygen. For these, the generators are housed on board the flying components like an aircraft, lighter than air balloon, or quadcopter. Once generated up in the sky, the electricity is sent to the ground via the tether which contains an electrical wire. The second type is called groundgen. Unsurprisingly, these have generators on the ground. For these systems to generate electricity, the airborne components like kites, sails, and drones fly out into the sky. As they fly out, they pull on the tether which in turn drives the generator on the ground, kind of like yo-yos flying out and being reeled back in. Most airborne wind energy systems use cross wind flying techniques. Circular or figure of 8 patterns amplify power production by increasing lift force, which scales to the square of the wind speed moving the aerofoil. As you can imagine, the aerodynamic forces at play are a wild mix of the actual wind speed and the kite's own speed, which creates a whirlwind of complex physics. It is perhaps unsurprising that so many of these systems have struggled in the real world, especially the flygen systems. Taking off in 2005, this giant inflatable donut from Altairos was the world's first commercial airborne wind turbine, reaching a reported altitude of 300 metres. The 30kW buoyant air turbine, or BAT, was kept aloft using helium and the on-board wind turbine generated electricity that was sent down to the ground station via its tether. The BAT was intended to work in rugged terrain unsuitable for wind turbines. It never fulfilled its promise of delivering electricity for 18 cents per kilowatt hour for remote, diesel-reliant communities and eventually Altairos pivoted to aerostat communication systems. Despite some positive demos, the system deployed in Alaska was eventually abandoned. I'm not 100% clear why it was abandoned, but it could have been technical issues or that the target market found the new technology too expensive which meant it couldn't be scaled up and therefore became economically inviolable. It has echoes of a more recent flygen system backed by Google, the 600kW Makani that had 8 rotors and generated power in flight. The airborne wind energy community was bitterly disappointed when Alphabet announced the end of Makani's funding in 2020, saying that the road to commercial viability was much longer and riskier than hoped. These flygen systems are useful for future research, but there are none in operation. Makani's wingspan was 26m and with so much of these ultra-complex systems being airborne, anything going wrong means game over. From the dual-purpose propellers-cum-turbines on the Makani system, combined with its autonomous flight, there is so much interesting engineering that I could cover and I think it might have to have a video all of its own. But instead of having all the electricity generated in the air, ground-gen systems may be a safer bet. Many companies in this niche have gone bust, but there's still a possibility of commercial viability. Veterans of the sector might be thinking, I've heard that before, but there are a few things that keep me hopeful for these systems. One is that higher altitude wind energy holds too much potential to ignore. Another is that there has been so many technological advances in automation and the materials used. So let's look into the companies that are working on these systems, right after hearing about today's sponsor Surfshark who made this video possible. Surfshark is a VPN service that gives you access on an unlimited number of devices with just one account. 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Now back to airborne wind energies and the companies in the ground gen space. The two we'll look at in this video both have systems in operation and bigger ambitions in the works. SkySails and KitePower are both ground gen, soft sail, tether type systems, and both rely on automation to maximise energy efficiency and minimise cost. Using relatively few materials, they're both highly mobile, connect to existing grids and produce electricity in high as well as low wind conditions. SkySails claim to be the first company in the world with a ready-to-order airborne wind energy system. A free-flying power kite is tethered to a launch and recovery system and has automated control. Then there's a generator on a rotating ground station producing electricity. The folded kite is taken out of storage and positioned for launch from a mast. Inflowing air unfolds the kite to full size. Once launched, a winch reels the tether out to altitudes up to 800m in the power generation phase. As it flies out during this phase, it drives a generator and produces electricity. After flying around in figures of 8, the maximum extension is finally reached. At this point, the retraction phase kicks in and the kite automatically adjusts its angle of attack to create a low pulling force. The generator now switches to act as a motor so it can reel the tether in. Once it's all the way back, the cycle can restart. For landing, the winch pulls in the tether completely and the kite is docked back to the mast which is then stowed away. It seems so beautifully simple and it only uses a small amount of the electricity it generates to reel it back in at the end. But getting the software right to autonomously launch and fly the kite took them 7 years. In terms of commercial viability, they have 100-200kW systems available for order and say that since 2021 they've been operational in Mauritius which is a beautiful island prone to hurricanes so not suitable for conventional wind turbines. I've asked to see if they have any hard data in terms of electricity generated or sent to the grid and I'll keep you updated in the comments if they reply. A recent milestone was a successful power curve test which is apparently the first externally verified test in the industry so things do seem to be progressing. Another company KitePower has something called the Hawk which is a neat system of portable energy. It produces 30kW of power and stores the captured energy directly into a 400kWh battery. Like SkySails, KitePower has big ambitions for the future and small units available to order right now. It works similar to SkySails with a soft wing driving a generator on the ground through the reeling tether. The inflatable sail has a fiberglass skeleton and its movements are tracked and controlled autonomously by the ground station. What's cool is that everything fits inside the 20ft shipping container that it arrives in. It's plug and play takes a day to set up and operates for 10 hours. Again I was dying to see an example of this out in the wild but I haven't heard back yet so I'll keep you updated. From what I've read though the Hawk has been learning to fly on a tropical island, this time a Dutch airbase in Aruba. I'm starting to think that I might have to go and visit some of these. KitePower also credits their success so far to advances in computing power but also materials in the tether which are as strong as steel but 7 times lighter. The operational radius area needed for launch and landing of the Hawk is around 50m but if you're thinking of setting one up in a nearby field you'll need to speak to several regulatory authorities. It's permitted in the EU as a drone and has some lights for operation at night as required by air traffic control. Depending on where it's placed though you might also need building and environmental permits. Which brings us to one of the major challenges faced by airborne wind energy systems and that's regulations and it's not a simple issue. Depending on jurisdictions they can either be regulated as drones or energy generators, a topic of great debate in the airborne wind energy community. A second challenge is the for something that's extracting energy from an unknown wind field using a 3D flight trajectory. The number of areas that need to be controlled for autonomous functioning is mind-boggling. A third massive challenge is how to win the confidence of investors when minor problems with small parts within complex systems make the technology look immature. With no funding, systems can't be refined by months or even years of actual flight. Apart from the challenges brought on by the insane complexity of these seemingly simple machines, another challenge is instability, which for airborne wind energy systems is a given. To operate all of their moving parts, automation systems have to find patterns in wind conditions that are also highly changeable. So they're constantly inferring and predicting the unpredictable in their quest to tame the wind and turn it into electricity with enough reliability to make the whole thing viable. Airborne wind energy systems are definitely a fascinating niche but there's a lot of criticism as to whether it will ever really take off. The basic idea of harvesting better wind using fewer materials is sound, but can the challenges to commercial scalability be overcome? As for birds, well the jury is still out on that one too. There are just not enough studies to back up claims that airborne wind energy systems are kinder to birds, so hopefully there'll be more research into this area. With the need for better autonomous flight controls and the advancements in AI that we're seeing, I can definitely see there being progress made. We might even see plans for kite wind farms, though they would have to stop the tethers getting tangled. But without any systems in prolonged use, it's hard to tell how quickly, or even if, airborne wind energy systems have credible prospects. However, that hasn't stopped many pioneers from other fields in the past from making the impossible, possible. So we're just gonna have to hang in there and wait for updates on some of these intriguing projects. As you're watching, please consider subscribing. It's free and will help keep you updated on future videos. Also, a more personal update is that I've just submitted my PhD thesis, which means I'm now officially full-time doing YouTube. This means I can spend mornings coming out to interesting places to film, and it also means that there'll be more interesting content on the channel. So please subscribe and thank you for your support.