Rare Earth Magnets in Wind Turbines
Worldwide addition of wind energy capacity has been breaking records year-on-year. As of 2021, global wind capacity stands at 744 Gigawatts, with an unprecedented 93GW added in 2020 (50% more than in 2019), despite Covid-19 supply chain disruptions.
This is sufficient to generate 7% of the world’s electricity demand. In the UK alone, a quarter of the UK’s electricity was generated by wind turbines in 2020. While the drawback of wind power is that wind is not constantly available, with increasing cost-competitiveness and developments in energy storage capacities, it is expected to continue making a substantial contribution in the transition to renewable energy sources from fossil fuels.
Permanent rare earth magnets are the most critical component in wind turbines. Permanent magnet generator technology (which supplanted the previous wind turbine models that used rotor windings) generate their own magnetic field, which eliminates the need for gearboxes and external power, thereby making them more cost-efficient, reliable, and low maintenance.
Neodymium-Iron-Boron (NdFeB) permanent magnets dominate the permanent magnet market, as the strongest commercially available magnet with exceptionally high energy density. This makes it optimal for the magnets to use electromagnetic fields to convert magnetic energy into electricity.
NdFeB magnets are vital not only to wind turbine generators, but also to electric vehicle traction motors, electric bikes, industrial robots and many other applications in which the magnets are exposed to high temperatures and strong demagnetisation fields.
NdBFe magnets typically contain approximately 30% of Neodymium, 65% Iron, with smaller additions of Boron (1%), Praseodymium (1%) and Dysprosium (2-8%) and other metals depending on the application.
The addition of Dysprosium in NdFeB magnets allows the magnets to operate at high temperatures. In electric vehicles, higher Dysprosium content is required due to the motors of electric propulsion in vehicles generating more heat. Therefore, demand for dysprosium oxide for EVs is expected to be quadruple the demand for wind turbines in the next decade.
Dysprosium is the heaviest and rarest of the Rare Earth Metals, making-up just over 1% of total global rare earth production (200,000mt per year), while Neodymium makes-up around 10-18%. Around half the demand for Neodymium comes from permanent magnets, whereas Dysprosium’s primary use is in NdFeB magnets.
Neodymium and Dysprosium are at significant supply risk which could be a hindrance to our transition into a greener economy. This is because China dominates 98% of global rare earth production. Separating the rare earth metals produces extremely toxic waste, and so China’s environmental policies have increasingly limited rare earth production while the US-China trade tensions during the Trump administration also contributed to tighter supply. While prices remain dictated by the whims of geopolitical policy and politics, there has yet to be a replay of the so-called “Rare Earth Bubble” which sent prices soaring to eye-watering heights in 2011, largely driven by speculation.
Although other regions such as Australia, Canada and US are beginning to start their own production in the next decades due to the strategic importance of these materials to transitioning into post carbon economies, it will be many years before they produce substantial quantities.