Wind turbines keep growing in size and power. That brings real engineering challenges, especially offshore, where maintenance is costly and hard to reach. LIGHTWIND is a European project developing a new drivetrain architecture to help address this. We have just completed its first test campaign, and the results give us confidence to move forward. We are now preparing a second testing phase to fine-tune the system further.
At the heart of the project is the OptiGen concept. It’s a modular drivetrain architecture for offshore wind turbines above 15 MW. The design replaces conventional main bearings with a wheel-and-rail system placed close to the generator air gap. Not familiar with what a drivetrain does, or why its weight matters offshore? We cover the basics in this article.
This configuration addresses some of the main challenges linked to increasing turbine power ratings, both onshore and offshore. These include larger structural dimensions and loads, heavier components, and the difficulty and cost of maintenance, especially offshore.
One of the main advantages of our concept, compared with conventional bearings, is easier maintenance. Technicians can monitor and replace components directly within the turbine. There’s no need to dismantle and transport the nacelle back to an assembly facility. We explain this in more detail in our article on modular drivetrains and what they mean for offshore wind maintenance.
First test campaign: positive results and next steps
Our starting point was a preliminary design based on the IEA Wind 15 MW reference turbine. From there, we identified the most critical components, particularly regarding fatigue. We also analysed the wheels’ and rails’ operating conditions, the loads acting on them, and suitable materials. We then developed a test rig to reproduce equivalent operating conditions on an accelerated basis and verify the system’s durability.
In parallel, we reproduced the mechanical system’s dynamic behaviour using a hexapod. This device, the Beat 1.1 from IDOM, is located at the Fraunhofer IWES facilities in Hamburg. It allowed us to evaluate the architecture’s performance under some of the most demanding operating conditions.
The results from this first test campaign have been positive and allow us to move into a new testing phase. Our technical team is now implementing improvements based on lessons from the first campaign. The aim is to continue validating the concept and increase its technological maturity.
These activities will bring the technology to Technology Readiness Level (TRL) 4. This moves the concept closer to future commercial applications and supports a new generation of high-power wind turbines.
As part of the same project, we will design a 22 MW version of the OptiGen system. This will use IEA Wind Task 55 as a reference. We will then assess whether the architecture can scale up to 30 MW. The results will show how the concept could apply to future, very-high-power wind turbines. At that scale, its advantages are expected to become even more relevant.
A video presenting the project and its technology
To mark this milestone, we are releasing an explanatory video. The video outlines the technological challenge we are addressing and how the OptiGen concept works. It also covers the main design, testing and validation activities carried out so far.
Beyond addressing the technical challenges of larger wind turbines, the OptiGen concept can also reduce the use of certain critical materials. One example is the rare-earth elements used in generator magnets.
New applications for the wheel-rail system
Our technological development is also opening up new applications for the wheel-and-rail system, beyond the project’s original scope. OptiGen has assessed alternative applications of the technology for other wind turbine components and architectures. These include a solution for turbines with geared drivetrains, and another focused on yaw and blade pitch systems.
Results to be presented in Hamburg
We will soon present our progress and results at WindEnergy Hamburg, one of the leading international trade fairs for the wind-energy sector. Topics on the agenda include the main results from our first test campaign, next steps, and plans for scaling up the concept.
Participation in the event gives us a new opportunity to bring our results closer to industry. It also helps us strengthen collaboration between research centres, engineering companies and industrial partners. This collaboration is one of our project’s fundamental pillars. It’s about turning research results into solutions that can have a real impact on the onshore and offshore wind industries.