Is there going to be a limit to how large wind turbines are going to get? Or will there come a point where despite the lightness of the material used for the blades, and the efficiency of the gearbox, the law of diminishing returns sets in, and it becomes too expensive to manufacture, transport to site, erect and maintain? I don’t know the answer to that, but so far the trend has been ever upward.
When I was a callow youth in the 1980s, the first commercial offshore wind turbine was created. It had blades that were fifteen feet long, longer than my car, and generated… wait for it… 30kW! The size and output have ratcheted up as new technologies and innovations are introduced- Some were saying that it wouldn’t be economically viable to create wind turbines of over 5MW capacity.
But Siemens think otherwise and they have just unveiled the biggest turbine anywhere in the world. With the definitely uncatchy name of the STW-6.0-154, it has three 75 metre blades and a rotor diameter of 154 metres. For comparison purposes that’s equal to the wingspan of an Airbus 380:
In thirty years this is how far we have come with wind turbines- this one will generate nearly 25,000 times as much power as Siemens’ original model. That’s enough to power 6,000 homes.
The turbine has been designed for use offshore only. Sucj turbines need to be more reliable given the vagaries of the weather, and the distance from the nearest maintenance source. So Siemens replaced two-thirds of the traditional drive train—the main shaft, gearbox and high-speed generator—with its proprietary Direct Drive system that instead uses a low speed generator connected directly to the low-speed shaft. The less parts there are, the less wear, so less maintenance, and less likelihood there is of replacements being needed.
What brought a smile to my lips was that Siemens obviously cares about its employees and contractors. The main body housing contains a coffee machine for servicemen! I wonder if that’s powered by electricity generated from the turbine?
The 6 MW turbine is capable of using either a specially built 154 meter rotor for maximum power generation or a slightly shorter 120 meter long blade, the same that the 3.6 MW model uses, for areas near airports and flight paths that have a 150 meter tip-height restriction. A number of these mega-turbines are planned to be built and sited along the English coast. However the first test turbine, needs to complete nearly two years of tests at the purpose-built testing site in Denmark.
