‘Permanent magnet machines feature higher efficiencies than machines with excitation windings (absence of field winding losses), less weight and the advantage of having no slip-rings and brushes. Machines above kilowatt range (and most below) employ high-specific energy density PM material, preferably of neodymium-iron-boron (Nd-Fe-B).’ —Wind Energy Systems for Electric Power Generation, by Manfred Stiebler, Springer, 2008
‘The data suggest that, with the possible exception of rare-earth elements, there should not be a shortage of the principal materials required for electricity generation from wind energy. ... Sintered ceramic magnets and rare-earth magnets are the two types of permanent magnets used in wind turbines. Sintered ceramic magnets, comprising iron oxide (ferrite) and barium or strontium carbonate, have a lower cost but generate a lower energy product than do rare-earth permanent magnets comprising neodymium, iron, and boron (Nd-Fe-B). The energy-conversion efficiency of sintered Nd-Fe-B is roughly 10 times that of sintered ferrite ... As global requirements for rare-earth elements continue to grow, any sustained increase in demand for neodymium oxide from the wind resource sector would have to be met by increased supply through expansion of existing production or the development of new mines. ... An assessment of available data suggests that wind turbines that use rare earth permanent magnets comprising neodymium, iron, and boron require about 216 kg [476 lb] of neodymium per megawatt of capacity, or about 251 kg [553 lb] of neodymium oxide (Nd₂O₃) per megawatt of capacity.’ —Wind Energy in the United States and Materials Required for the Land-Based Wind Turbine Industry From 2010 Through 2030, by U.S. Geological Survey, U.S. Department of the Interior, Scientific Investigations Report 2011–5036
‘Five rare earth elements (REEs)—dysprosium, terbium, europium, neodymium and yttrium—were found to be critical in the short term (present–2015). These five REEs are used in magnets for wind turbines and electric vehicles or phosphors in energy-efficient lighting. ... Permanent magnets (PMs) containing neodymium and dysprosium are used in wind turbine generators and electric vehicle (EV) motors. These REEs have highly valued magnetic and thermal properties. Manufacturers of both technologies are currently making decisions on future system design, trading off the performance benefits of neodymium and dysprosium against vulnerability to potential supply shortages. For example, wind turbine manufacturers are deciding among gear-driven, hybrid and direct-drive systems, with varying levels of rare earth content. ... Neodymium-iron-boron rare earth PMs are used in wind turbines and traction (i.e., propulsion) motors for EVs. ... the use of rare earth PMs in these applications is growing due to the significant performance benefits PMs provide ... Larger turbines are more likely to use rare earth PMs, which can dramatically reduce the size and weight of the generator compared to non-PM designs such as induction or synchronous generators. ... Despite their advantages, slow-speed turbines require larger PMs for a given power rating, translating into greater rare earth content. Arnold Magnetics estimates that direct-drive turbines require 600 kg [1,323 lb] of PM material per megawatt, which translates to several hundred kilograms of rare earth content per megawatt.’ — Critical Materials Strategy, by U.S. Department of Energy, December 2011
‘In the broader literature ..., concerns have been raised about future shortage of supply of neodymium, a metal belonging to the group of rare-earth elements that is increasingly employed in permanent magnets in wind turbine generators.’ —Assessing the life cycle environmental impacts of wind power: a review of present knowledge and research needs, by Anders Arvesen and Edgar G. Hertwich, 2012, Renewable and Sustainable Energy Reviews 16(8): 5994-6006.
‘A single 3MW [direct-drive] wind turbine needs ... 2 tons of rare earth elements.’ —Northwest Mining Association
Also see:
- Rare earths, minerals used in windpower technology, could fall into short supply, Windpower Engineering & Development, June 4, 2013
- Wind turbine & generator magnets, First4Magnets (‘In every wind turbine and generator you will find one or more incredibly strong magnets. Simplified, the rotating shaft of a wind turbine is connected to one or more strong magnets, usually neodymium magnets, these magnets turn relative to an assembly of coiled wire, generating voltage in the coil.’)
- Neodymium magnets in wind turbines & generators, Stanford Magnets
- Clean energy's dirty little secret, The Atlantic, May 2009
- Are rare earth minerals too costly for environment?, PBS News Hour, December 14, 2009
- In China, the true cost of Britain's clean, green wind power experiment: Pollution on a disastrous scale, Daily Mail, January 26, 2011
- Rare-earth mining in China comes at a heavy cost for local villages, The Guardian, August 7, 2012
- Rare earth mining in China: the bleak social and environmental costs, The Guardian, March 20, 2014
- Rare earths: Elemental needs of the clean-energy economy, Scientific American, October 13, 2010 (‘A massive wind turbine—capable of turning the breeze into two million watts of power—has 40-meter-long blades made from fiberglass, towers 90 meters above the ground, weighs hundreds of metric tons, and fundamentally relies on roughly 300 kilograms of a soft, silvery metal known as neodymium—a so-called rare earth. This element forms the basis for the magnets used in the turbines. "Large permanent magnets make the generators feasible," explains materials scientist Alex King, director of the U.S. Department of Energy's Ames Laboratory in Iowa, which started making rare earth magnets in the 1940s as part of the Manhattan Project. The stronger the magnets are, the more powerful the generator—and rare earth elements such as neodymium form the basis for the most powerful permanent magnets around.’)
- The dystopian lake filled by the world’s tech lust, BBC, April 2, 2015
- The dark side of renewable energy, Earth Journalism Network, August 25, 2016
- Poison wind, Today Tonight Adelaide, March 1, 2017 (‘Clarification: This story contains details of toxic pollution associated with the use of rare earths in the production of wind turbines, cars and household electronic items. We wish to clarify that the wind industry estimates one in five turbines in South Australia use rare earths. South Australia has approximately 40 wind farms operating or seeking approval, with almost 700 individual turbines. Using the industry’s figures, South Australia has in excess of 100 turbines which use rare earths, which is a very significant number.’)
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