This new concept wind turbine is unlike any you’ve seen before
The type of wind turbine you are used to seeing in stock photos of wind farms is called a horizontal axis wind turbine (or HAWT). But there is another form of wind power, called a vertical axis wind turbine (VAWT), in which the blades rotate on an axis perpendicular to the Earth’s surface. This type of turbine can work better in unstable wind conditions as they do not need to be pointed into the wind, but still produce much less electricity and have durability issues due to the force the wind exerts on them. That’s why you would only see VAWTs in small applications, like homes, and HAWTs in wind farms.
But a new company claims to have improved the design of the VAWT. The invention could create a turbine with a maximum power of 40 megawatts, far exceeding the 15 megawatts of the current largest turbine in the world. This company is called global wind, a Norwegian startup. The Norwegians, rich thanks to their oil and gas reserves—want to dramatically increase their wind power generation to 30,000 megawatts by 2040. Their industry the interest in offshore wind energy is so great that there is a waiting list to test new technologies off its shores, which are on the incredibly windy shores of the North Sea.
In June 2021, company founder Stian Valentin Knutsen wondered if it would be possible to have two sets of rotor blades on a single turbine mast, rotating them in opposite directions. “The idea was to increase the power output of vertical turbines while simultaneously eliminating the increased torsional forces and inherent problems associated with scaling traditional HAWTs for increased power output,” m company spokeswoman Elsbeth Tronstad said via email. Knutsen sought out scientists to test the possibilities and eventually met Hans Bernhoff, a professor at delectrical engineering department at Uppsala University, Sweden.
According to the company, Bernhoff had been researching vertical wind turbines for more than 20 years, building his own 200-kilowatt (kW), 131-foot-tall vertical turbine that operated for a decade. He was intrigued by Knutsen’s theoretical model and joined the company, developing the idea of the large tilted offshore floating turbine that World Wide Wind is currently working on.
How it works
The concept of vertical axis turbines isn’t new, but the architecture of this machine, which the company says is patent pending, is radically different. The design uses two coaxial or counter-rotating rotors mounted on a vertical shaft.
Each rotor has three blades that sweep in an inverted conical area thanks to its V-shape (reminds me of the arms of a mechanical shaft). The upper turbine is connected to an inner shaft which serves as the rotor in the electric generator. The lower turbine acts as the stator, the part of the generator that contains the coils and remains static in most generators. In this case, however, the stator moves to the opposite side of the rotor. The result: It doubles the relative speed of the shafts and therefore the electrical production capacity of the system.
Their engineers point out that the generator is not at the top of the mast, like that of a classic HAWT system. but at the base, next to the ballast and all the other components of the electrical system, including the cables that connect it to the shore. The extra weight contributes to the stability of the system, ensuring that the tower does not capsize, regardless of the uplift of the ocean. This design, they say, also makes it more resistant to vibrations which greatly affect the integrity of HAWT systems, especially in very high wind conditions.
While an underwater generator looks like a nightmare to maintain, Tronstad tells me that’s not a problem: “Its interior space is all dry and there’s enough space for technicians to work on it. interior.” She also says that the design of the generator is a direct drive permanent magnet synchronous generator“which requires minimal, if any, maintenance during operation”, thanks to its absence of a gearbox and other wearing parts.
Too good to be true?
Logically, the mast itself does not stand up like in conventional towers. Indeed, the mobility of the assembly to be able to operate from almost any angle is fundamental for its operation. “Bernhoff – who is also a competent sailor – always wanted to design an offshore turbine that would work with the wind and not against it, as current offshore HAWT units do,” says Tronstad. The company claims that this machine automatically steers when the wind blows and absorbs its energy from every conceivable angle, always ensuring the highest possible performance.
Knutsen and Bernhoff also argue that counter-rotating rotors greatly decrease turbulence typical of horizontal turbines. But at the same time Tronstad says that “the first turbine-driven counter-rotating generator has already been tested” and that they have simulated the full-scale generator design with electromagnetic with full physics, as well as hydrodynamic simulations of the structure and the wave interaction”, and other tests are currently underway, the company has not yet built its first full-scale prototype to physically validate any of these simulations.
If their simulations and theories are true, however, it could lead to crazy machines. According to its inventors, this design can reach up to 1,312 feet in height to reach up to 40 megawatts. The tallest turbine on the planet right now is the one in China, 793ft tall MySE 16.0-242 Chinawhich generates up to 16 megawatts using monstrous 387-foot blades.
But if the World Wide Wind design works, we wouldn’t need to build on such a gargantuan scale to get more power per square mile than what we’re getting in an offshore wind farm now. HAWT units require very large distances between them to avoid causing turbulence between them; but World Wide Wind says its machines can be deployed in higher density, thanks to the vertical design, increasing power generation using much less space.
These are all bold claims. The company is confident it will achieve these goals based on current testing, and Knutsen appears to have key support from Norwegian energy partners, an organization dedicated to the internationalization of Norwegian energy companies. Yet, as with any bold new innovation, it has to work in reality, not just in models; but any radical new idea that could have a significant impact on the wind energy industry and our planet is worth developing and testing. And we could see, before too long, how the company can deliver on its promise: World Wide Wind announces that it will launch its first 3-megawatt model in 2026 and a 40-megawatt model in 2029.