In November, a 3.6MW wind turbine in Denmark had its permanent magnet generator replaced by a high-temperature superconducting (HTS) ceramic as part of the EU-funded EcoSwing project. The superconductor reduces the size of the generator and replaces about 1t of neodymium (Nd) used in NdFeB permanent magnets with about 1kg of the rare earth gadolinium (Gd) used in the superconducting composite tape: gadolinium–barium–copper oxide (GdBaCuO).
Rare earth NdFeB magnets currently offer the highest power-to-weight ratio in the magnet industry and offer the highest efficiency in converting electrical energy to mechanical energy in motors, or vice versa in generators. Over the past few years, the two fastest growing markets for NdFeB magnets have been wind turbine generators and electric vehicle drivetrain motors. Amongst others, these applications illustrate the role and importance of rare earths in new energy technologies.
The top performing wind turbines are based on rare earth permanent magnet synchronous generators (PMSGs) using NdFeB magnets. PMSGs require less maintenance than traditional geared technologies and have, therefore, become the most compelling technology for use in off-shore wind farms. Wind turbine producers were exposed to volatile rare earth prices in 2011 after the application had accelerated to account for over 7% of the NdFeB market. As a result, the uptake of rare earth generator technology slowed in the wind turbine industry and producers established alternatives to reduce the requirements of rare earths. Roskill estimates NdFeB magnets to have captured around 20-30% of the wind turbine market.
Gadolinium is a lower cost rare earth and can also be used in the formulation of NdFeB magnets for lower quality applications, but its use is limited because of the lower availability of gadolinium compared to neodymium. The use of small volumes of gadolinium in superconducting tape may reduce the reliance on neodymium supply, however, it exposes the wind turbine market to the lower volume rare earths that follow the same supply fundamentals. As a result of a tightening supply, Gadolinium is the only rare earth to have increased in price over 2018, seeing a 40% rise from US$13.3/kg to US$18.4/kg as of end-November.
Roskill’s new Rare Earths: Global Industry, Markets & Outlook report was published in December 2018 and includes supply, demand and price forecasts out to 2028, along with profiles of major producers, processors and end-users. Click here to download the brochure and sample pages, or to access further information.