On 5 January 2026, the skies of Yibin were briefly darkened by the S2000 Stratosphere Airborne Wind Energy System (SAWES) – a buoyant air turbine (BAT) measuring 60m in length, 40m in width and 40m in height (197 × 131 × 131ft).

The helium-powered platform rose to around 2,000m (6,560ft) in 30 minutes, generating 385kWh-hours (kWh) of power for the local grid, making it the world’s first megawatt-scale high-altitude wind power device to be formally connected to the grid. 

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The trial’s success has reopened conversations around BATs, yet it is not engineering challenges that have held the technology back but commercial viability. The design undoubtedly works, but experts have expressed doubt around SAWES’ business case, pointing to airborne wind’s checkered history.

Altaeros Energies attempted a similar design; founded in 2010 by MIT researchers, the company successfully demonstrated its BAT in 2014, but development stalled, and Altaeros pivoted to the relatively commercially secure telecommunications sector.

Elsewhere, Makani drove innovation in the airborne space with its aerodynamic solution: massive rigid kites that generated energy from crosswinds at around 300m. Its M600 prototype had a rated capacity of 600kW and a 26m wingspan. However, the company closed in February 2020, saying it “failed to find the investment needed to carry the technology forward”.

Yet airborne wind has seen some success in the shape of smaller, lighter designs, particularly in the soft-wing kite space, led by companies including Kitepower and SkySails. These comparatively cheaper solutions capitalise on crosswinds at lower-altitudes than BATs, using ground-generation systems to produce electricity, rather than on-board generators and cables.

“The SAWES solution is just huge, on a different scale than we are used to,” comments Roland Schmehl, associate professor at the Delft University of Technology and co-founder of Kitepower. “When you make something very large and deploy it, you incur huge costs without knowing whether it will eventually work.”

The question, then, is if the S2000 SAWES can succeed where similar airborne wind designs have failed – and whether Beijing-based Linyi Yunchuan Energy Technology has found a solution to commercial viability that other players missed.

Reaching new heights: the S2000 SAWES

The S2000 SAWES model consists of an aerostat, which sits around an integrated power generation structure including 12 100kW turbine-generator units. At 2000m, these can harness high-altitude winds and transmit electricity to the ground via the tether cable, which also stabilises the platform. 

Like the Altaeros design, the S2000 SAWES is helium-powered. The aerostat inflates and rises, but stabilising something large at height incurs engineering complexity, as associate professor of mechanical engineering at the University of Michigan Chris Vermillion observes. “A system that is lighter than air and does not have to continuously execute periodic motion will at least have the perception of being simpler,” he says.

“However, there are real challenges with building the helium structure, ensuring helium retention at all times, and dealing with features like updrafts and downdrafts, especially with a multi-tether system that makes launch and landing easier but causes very interesting dynamics in the air.”

To minimise leakage, the SAWES team reportedly developed a specialised material: a resin-based composite structure, interwoven with carbon fibre and Kevlar, using a layered technique to create a tight ceiling to trap the helium. According to recent academia, the airborne wind space will benefit from nano-enhanced composite materials in the future; carbon nanotubes and graphene may be incorporated into polymer matrices to improve strength, fatigue resistance and ultraviolet (UV)-aging resistance.

The crucial engineering distinction between BATs and kite models is how the designs fly. Kites use traditional, affordable and accessible ship sail material to fly using aerodynamics – just like normal kites. Meanwhile, the S2000 SAWES rises because of helium – an expensive raw material that is subject to volatility. In 2024, prices sat at around $500 per thousand cubic feet, but forecasts suggest this could reach $2,000 in 2026, as disruptions to liquid natural gas supply chains in the Middle East drive up prices (helium is a byproduct of natural gas production).

This heavy capital burden was one reason Altaeros abandoned its BAT business case, according to Schmehl. Tens of thousands of cubic feet of helium would be required, and leakage is inevitable. “With all types of balloons, the molecules penetrate the hull,” he explains.

Staying connected: materials and tethering

Material considerations are not only focused on containing what lies inside. A recent paper on airborne wind energy systems (AWES) identifies challenges for both kite models and BATS: coupled degradation from diurnal temperature variations, UV radiation, moisture and cyclic loading.

According to Schmehl, cyclic loading is airborne wind’s “biggest challenge”.

“When you have an inflatable device, a phenomena called flutter occurs, like a flag in the wind. This dynamic movement presents quite a stress on the fabric – fatigue – and for flexible membrane materials this is significant, causing degradation over time.”

TNO’s senior wind energy consultant, Josep Breuer, agrees, citing the sector’s biggest challenge as durability. “The system works. We can produce electricity with airborne systems. The question is whether we can do it not for a week or a month but for years.” He argues that the low-cost sails used for kite models lend themselves to this consideration, as while the kites too “need replacing in soft systems sometimes – maybe annually – they are relatively cheap, so that is not an issue”.

Leakage aside, the blimp has to be tethered and capable of transferring its generated electricity to consumers on the ground. The conductive cable was once an engineering feat, but the airborne wind industry has shared much of its engineering successes, informing each other’s designs over the years.

Makani opened its patent and technical data in 2020, sharing its design for a conducting cable used for its hard-wing kites, designed to withstand severe environmental stress. It describes the conductor as “a transmission cable arranged in an undulating path within the tensile cable, wherein an amplitude and a wavelength of the undulating path vary in relation to a force acting on the transmission cable”.

Schmehl explains what this looks like in practice: “The tethers are made of plastic, ultra-high-density polyethylene, or something similar, with molecules that are all in one direction to give this extra strength.” This, he says, is combined with a metallic conductor, providing conductivity.

Large-scale airborne wind deployment

Some scholarship suggests the S2000 SAWES airborne wind model can see success via “efficient and robust multi-aircraft cooperative clusters”. This means that large-scale deployment could look somewhat futuristic – a sky speckled with clusters of giant blimps and kites.

Yet location will be crucial. The S2000 was trialled in the prefecture-level city of Yibin – accessible to the grid and consumers but removed from easy landing space and directly in tightly regulated airspace. Meanwhile, the airspace challenge has proved a significant hurdle for European AWES developers, as flying systems require approval from aviation authorities, which have been slow to act.

Secretary general at Airborne Wind Europe Kristian Petrick expects that China will overcome these regulatory hurdles faster: “China’s five-year plan for energy includes airborne wind energy, so there appears to be supportive policy behind research activities. It is a big difference to Europe, unfortunately.”

Airspace aside, land space will also be a consideration. Although BATs are expected to support the power demand of urban spaces, regular landing is inevitable for safety, maintenance and during extreme weather. This means ample space is required and, despite being trialled above one of the biggest cities in the world, inner-city mass deployment of the S2000 SAWES is unlikely.

“It is better to have some clear space,” says Schmehl. “Cities are therefore probably no-gos, but that is the case for normal wind turbines too.” Instead, he suggests that airborne wind is likely to thrive in similar environments to land-based turbines – in elevated, offshore or open environments.

The nature of the design also makes the solution potentially attractive to remote operations, particularly in mining and construction, where some pilot customers are already trialling the solution. Disaster zones may also benefit from the moveability of AWES, particularly as capacity promises to improve.

Is the S2000 SAWES really a game changer?

Currently, the S2000 model’s capacity is contentious. It has achieved a 3MW-rated power output – similar to the annual generation of a typical onshore wind turbine – but experts remain sceptical.

“If you look at size and specifications, you can work out capacity based on rotor area and assumed wind speed at altitude,” comments Breuer. “I am sure it is not in the megawatt range.”

“I will only believe it when I see it,” echoes Schmehl, pointing out that Makani achieved a rated capacity of 600kW before the project closed, but achieved only “a fraction of that” during prototype testing.

He is more confident in SkySails’ Kyo system, which has been rated at 450kW. The system was used to validate the world’s first performance curve for airborne wind in 2024, pushing the sector from a theoretical concept into a commercially viable technology. Yet, despite the milestone, the European industry hasn’t exploded into commerciality, and Petrick expects airborne systems to remain small-scale in the foreseeable future.

“Research shows that for some systems, up to 500kW may be ideal, as there could be the market to sell thousands of smaller systems for distributed generation – like photovoltaic systems,” he adds.

While it will still take a few years until full deployment of AWE systems, Petrick states that “we have seen some good progress, with the first companies starting to commercialise their systems, followed by other companies entering the market with their prototypes”. 

Mass production of SAWES is reportedly already under way, with the first units set to connect to the power grid in 2026. However, questions remain over costs.

“We need to get costs down to around $0.20 or $0.25 [per kWh] to make a viable business case at this stage.”

In comparison, residential natural gas in the US has sat between $0.009 and $0.01/kWh in April 2026. Onshore wind was around $0.034/kWh in 2024, while offshore wind was around $0.079. As land-based wind energy solutions dropped in price, fewer AWES appear commercially competitive to investors or adopters.

Some researchers suggest that the SAWES S2000 could generate electricity as cheaply as $0.10/kWh, although the high costs associated with helium and the manufacturing process make the estimate appear optimistic. These estimates also depend on the S2000 generating electricity at its controversial 3MW capacity.

Wind speed is also a variable factor, and there is debate around the degree of advantage offered by altitude. Vermillion asserts that kite models, which rely on crosswinds rather than high altitude, have a higher chance of transforming the wind market.

“Stationary, buoyant systems are going to have a very difficult time outperforming crosswind systems on a power to mass ratio basis,” he explains.

“A crosswind kite is essentially eliminating both the tower and blade roots from a traditional towered system, whereas a buoyant system just eliminates the tower but still requires an equally large rotor to generate a given amount of power at a given wind speed. Yes, wind speeds are higher at higher altitudes but not so much higher as to outweigh this important benefit of crosswind kites.”

Ultimately, the AWES sector is facing a commerciality question, rather than an engineering one. “The sector’s true challenge is to make this competitive against other renewable energies,” concludes Schmehl. “Realism has kicked in that this might still take quite some time.”