In a recent article in the Guardian Review on wind energy, Adam Vaughan reported that Britain accounts for more than half of the new offshore wind power capacity built in Europe last year . . . adding, “Soon turbines will almost be as large as the Shard, Europe’s tallest building. The average capacity of the 500-plus turbines connected to the grid was up by more than a fifth on the year before, with 17 windfarms on average a third more powerful”.
Rex Harris (Professor of Materials Science) and three colleagues commented on this ‘up-beat view of off-shore wind farms which are certainly showing a lot of promise, particularly with regard to the very expensive and increasingly problematic nuclear option’.
They pointed out that there was no mention in the article of the vital role played by NdFeB -type permanent magnets* in the direct drive generators provided by companies such as Siemens, adding:
“As an approximate guide, such generators require something between 0.5 and 0.75 tonne per MW of these magnets. Thus a 7MW direct drive machine will require upwards of 3.5 tonne of sintered magnets. Being direct drives, these turbines have significant advantages over the geared variety but, currently, a possible downside is that the fully dense sintered magnets are provided predominantly by Chinese companies.
“With regard to the medium to longer term, this could present a major problem because China, which controls 95% of the global rare earths market, has its own ambitious plans to replace its current reliance on coal with a range of clean energy technologies including wind generators, both on and off-shore.
“With this medium to long term threat to the magnet supply, very much in mind, the West, including Europe and the USA, should recreate its previous manufacturing capacity for the production of NdFeB-type sintered magnets and start to exploit alternative rare earth reserves and develop and support NdFeB-type magnet recycling.
“Simply leaving matters to market-forces will, almost certainly, not be sufficient.”
Rex Harris, David Kennedy, Adrian Arbib, Allan Walton.
*Ed: Neodymium Iron Boron (NdFeB) magnets are the most powerful and advanced commercialized permanent magnet today. As they are made from Neodymium, one of the most plentiful rare earth elements, and inexpensive iron, NdFeB magnets offer the best value in cost and performance.