aerodyn engineering has recently designed a new 8MW offshore turbine, which is based on Super Compact Drive technology, and has just found its first licensee in mainland China. Founder and owner Sönke Siegfriedsen explains why this turbine is so well suited to harsh offshore conditions.
How did your new turbine come about?
Sönke Siegfriedsen: I founded this company 30 years ago in 1983. Since then, we have developed a lot of turbine parts, from the blade to the foundation, including electrical systems in 5-6MW power classes. We have designed around 30 turbines for different manufacturers around the world and began designing offshore turbines 15 years ago.
We think that the next generation of turbine, especially in European waters, needs to be larger in order to bring down costs, and we can ensure this with our new and different type of turbine design.
Your new turbine design is based on Super Compact Drive (SCD) technology – could you explain a bit more about that?
The idea behind this technology was that the turbine manufacturer or licensee can produce parts by themselves. You can either supervise the production process, selecting the parts and producers yourself, or you can do it all single-handedly, as our Chinese licensee is doing. You get all the production drawings and specifications that you need for each part, meaning the whole quality management process is much better controlled.
What are its principal advantages?
It’s a very compact and lightweight design, and every part is optimised. The use of a two-blade rotor is also very important. It has a rotor rate that is just 70% of a comparable three-blade rotor, so you save a lot of money, and you can also reduce the loads in extreme conditions to a horizontal parking position. While a two-blade rotor has a greater visual impact and higher noise emission, such qualities are not important offshore.
What SCD projects have you realised so far?
We started with a 3MW turbine design four years ago, and several turbines have already been built from this design.
Our licensee in China has a wind farm with 17 turbines running in very rough conditions. There’s another near-shore project not far away from Shanghai and a smaller project in South China, where the prototypes and modifications will be tested next year. Another big project with 29 turbines has been realised in the South China Sea, between Macau and Hong Kong.
How does the new design build on your previous SCD projects?
The 6 and 8MW offshore turbines follow the same SCD principles as our 3MW onshore turbine, but are downwind turbines. The 6MW turbine was specially designed for Chinese water with a large rotor diameter, while the new 8MW type has been tailored to the European or Japanese markets, where wind conditions are stronger. In the case of typhoons, the turbine can be stopped in a horizontal position and can turn automatically in the direction of the wind without any power consumption.
Compared with normal three-blade rotors, we can reduce the loads by a factor of five to six. That means we can survive a class four typhoon, which is very important for customers in parts of South China.
The biggest difference between this new design and previous ones is that we are using carbon blades. This is necessary with turbines of this size because it makes them more lightweight and stiff, resulting in less deformation on the blade. This turbine is also well suited to floating foundations, which are becoming increasingly popular.
How can it help operators save time and money?
You can assemble the whole turbine in the harbour, which means transporting and erecting it will be much easier because you only need one lift. Also, in the case of a defect, you can completely change it easily; this is much more time-consuming and expensive with the three-blade rotor. Operators can save money in the production of the turbine, but also in assembly, transportation, repair and maintenance.
Another key point is that we have a helicopter landing platform, which is very useful – especially in the North Sea – and makes it much easier to bring out service staff or materials.
Where are you looking to install it?
We are looking at all markets in the US, Europe and Asia, with different types suited to different regions. We are in discussions with customers from the US, Japan and Europe, and they are very interested in this design.