Anders Nielsen (right), who became the chief technology officer (CTO) of Danish turbine manufacturer Vestas in May 2020, likes to compare the wind industry with truck, rather than car, manufacturing.
If you take German car manufacturer Volkswagen group as an example, he argues, in 2019 it produced some 10 million vehicles, of which 200,000 were trucks.
Global wind turbine volumes, while increasing fast, are still much smaller. Vestas, with an 18% world market share, produced around 3,000 turbines of different models and sizes last year.
“What trucks and wind turbines have in common, when it comes to manufacturing, is that both handle large, heavy components and systems. And they are both business-to-business type industries involving machinery tailored to meet specific customer needs,” says Nielsen. “This in turn requires, in both industries, a deep knowledge of customers’ wishes and an understanding of what drives their business.”
For modern wind turbines, in Nielsen’s view, this means continuously optimising annual energy production (AEP) while also reducing complexity and the overall risk profile.
A dedicated modular approach is essential to achieving these preconditions at the same time as matching specific application requirements. It would be impossible to supply a unique truck or wind turbine to each individual customer.
The main purpose of modularity is to carry over proven technologies and well-established smart solutions from one tailored product platform to another. One good example coming from the modular Vestas EnVentus platform philosophy is to deploy a one-size main bearing unit for multiple turbine models, which allows cost savings by producing high volumes of a single component.
There are practical limits, however, when platform differences are too big — for example if you are trying to fit a 4MW-size gearbox in the physical space of a 2MW nacelle. In “big to small” transfer cases, it can also prove very difficult for module cost levels to follow turbine downscaling, says Nielsen.
However, modularity is very effective when similar range components and systems can be used. “A perfect modularity example that works is the latest V155-3.3MW turbine addition to the 4MW platform, which — compared with the V150-4.2MW model — has an enlarged rotor and reduced rating. This new model variant was created to a large extent reusing similar-range components and systems.”
The V155-3.3MW shares, for instance, the geometrical shape of the inner blade with the V150, allowing for partial mould reuse. The V105, V112, V117, V126, V136, V150 and V155 all share the same root diameter as well.
Nielsen believes that comparable modularity benefits could be applied to hydraulic pitch control systems for various platforms. For several key components, the function of systems rather than turbine rating is the main determinant of size, he adds.
Partnering with ZF
Vestas entered a partnership with ZF Wind Power in early 2017 to jointly develop, test, validate and series-produce EnVentus drivetrains. A first complete prototype emerged in January 2020.
An essential aspect of this “next-generation” project is that ZF produces the medium-speed gearbox, as well as the main bearing unit, and merges these into a sub-assembly. In the next step, this is merged with a Vestas or third-party permanent magnet generator into a full drivetrain.
The main bearing unit serves as a key structural drivetrain element. It is made up of a heavy-duty cast housing with a main shaft and two taper-roller bearings. This unit is mounted on the cast bedplate and supports the rotor at the front. At the rear, it provides flanged connections to both gearbox and generator.
Complete drivetrain modules are pre-commissioned in the factory, prior to delivery and installation on site. The ZF facility in Lommel, Belgium, where EnVentus drivetrains are to be series-produced, has direct access to a nearby river with port facilities.
According to Nielsen, the ability to produce a complete, fully integrated 6MW EnVentus drivetrain in a single facility is a win-win formula from many perspectives. “Among its many benefits, it offers the most efficient way to produce and factory pre-commission large-scale EnVentus drivetrains while adding new levels of product and process flexibility,” he says.
“Road-transport logistics can be further optimised to match the overall requirements of each wind farm. In combination, these and other factors have a substantial impact on lowering the levelised cost of energy (LCoE) for drivetrains and complete turbines.”
Before deciding on this novel integrated drivetrain production approach, Vestas experts checked road transport feasibility for eventual bottlenecks by carefully mapping road transport routes in their main markets and for different application scenarios.
As wind turbine systems get bigger, LCoE will likely not decrease further but start levelling out instead, says Nielsen. He also notes that road transport and installation logistics for increasingly longer and wider rotor blades could ultimately prove the limiting factor for onshore wind.
That is one of the reasons why he believes that the development, testing and validation, between 2016 and 2018, of a 900kW multi-rotor turbine with four rotors was an interesting experiment. But Nielsen refrains from commenting further on a possible future role for such “radical” wind technology within the Vestas product portfolio for onshore and offshore.
As for predictions on the possible direction of technological advances for wind turbines in terms of both type and scale, he remains on the fence. “I am still a newcomer in the wind industry, which I joined at a rather mature stage of my career. What amazed me, especially at the beginning, were the high levels of science and technology in all the main fields including mechanical and electrical engineering, turbine control and rotor aerodynamics,” he says.
“I am particularly happy to have now become part of the ongoing green transition movement, in which Vestas should play an increasingly important role.”
Decarbonisation offers huge opportunities in technologies such as energy storage, and in keeping electricity networks stable with a growing share of renewable-energy generation sources, according to Nielsen. He is keen to ensure Vestas will have a strong position in these crucial areas.
Another key aspect of sustainability for Nielsen is product lifecycle performance, which requires deep knowledge and full understanding at a high-systems level.
Specific markets and market developments will ultimately drive cost-effective solutions. For that reason, it is crucial to always take a close look at what happens where. The value of electricity, for example, could become a main driver for optimal turbine configurations in specific markets both onshore and offshore.
Repowering, where existing sites with “old” turbines are given a new lease of life through redeployment with new enhanced modules where feasible and applicable, is another interesting sustainability-related opportunity Nielsen points to.
He remains hesitant when asked about future plans for the offshore business, which is to return under full Vestas ownership following the announced acquisition from Mitsubishi Heavy Industries (MHI). He flags up restrictions during the ongoing transition period, and will not be drawn on any specific scenario.
“What I learned during my more than 25 years in the truck business is that the key is not standardisation of components and systems, but modularisation,” he says, pointing to the V155-3.3MW as a good example of a tailor-made solution for the Indian market, but based on a turbine model suitable for the global market.
“Adapting and responding fast to market dynamics requires — besides smart solutions being carried over to tailored turbine platforms — a willingness to learn from other industries, including those that have been making trucks for decades”, Nielsen concludes.
The Vestas answer to the cost and complexity of fast-paced innovation?
In order to keep up with the increasing pace of innovation and growing market demands, in 2012 Vestas initiated a transition process to modular product development. Whereas between 1980-90 Vestas had introduced six product variants, in 2010-20 it launched 12 new turbine variants.
The conventional approach to product development offered limited synergies between products, increasing complexity and resource management. The answer to cost and complexity in other industries has been to embrace modularity principles. By actively pursuing this direction, Vestas was able to utilise resources more efficiently in the long term.?
Modular turbine architecture breaks down complex products into individual modules, each contributing to the ultimate purpose of a wind turbine system. Each module is based on a technology concept, design rules, value chain processes and standard interfaces to connect with adjacent modules.
Over time, different reusable module variants are developed to meet customer needs while complying with the defined architecture. This allows the creation of new product variants by using changed/adapted modules rather than developing an entire new wind turbine every time.
In 2020 Vestas has installed prototypes of the V162-6.0 MW and the V150-6.0 MW EnVentus modular medium-speed platform, with first commercial installations planned before the end of the year.