Influence of Rare Earth Element Supply on Future Offshore Wind Turbine Generators

Rare-earth elements have become very valuable to many industries, including the renewable energy industry. As their usage has spread, their demand has increased dramatically. At present, the vast majority of rare earth elements are mined in China. China is also the world‟s leading consumer of rare earth material, and there are indications that Chinese rare earth exports will decrease in the near future as China seeks to maintain a sufficient supply of these materials. The magnetic properties of some particular rare-earth elements have made them very useful in producing high power density electrical machines. Such machines are utilized in applications such as electric cars, and wind turbines. This paper will examine the rare earth supply issue, in order to comment on its relevance to the wind turbine industry. The wind turbine topologies which are currently being used are compared, highlighting their advantages and disadvantages in serving as long term solutions for offshore wind farms. Finally, a direct drive induction generator and a high temperature superconducting generator topology, which respectively are not and very little dependent on rare earth elements, are presented as candidates for use in future offshore wind turbines.