For three weeks, China has blocked shipments of rare-earth minerals to Japan, a move that has boosted the urgency of efforts to break Beijing’s control of these minerals. China now produces nearly all of the world’s supply of rare earths, which are crucial for a wide range of technologies, including hard drives, solar panels, and motors for hybrid vehicles.
In response to China’s dominance in production, researchers are developing new materials that could either replace rare-earth minerals or decrease the need for them. But materials and technologies are likely to take years to develop, and existing alternatives come with trade-offs.
China apparently blocked the Japan shipments in response to a territorial squabble in the South China Sea. Beijing has denied the embargo, yet the lack of supply may soon disrupt manufacturing in Japan, trade and industry minister Akihiro Ohata told reporters Tuesday.
Rare earths include 17 elements, such as terbium, which is used to make green phosphors for flat-panel TVs, lasers, and high-efficiency fluorescent lamps. Another of these elements, neodymium, is key to the permanent magnets used to make high-efficiency electric motors. Although well over 90 percent of the minerals are produced in China, they are found in many places around the world, and, in spite of their name, are actually abundant in the earth’s crust (the name is a hold-over from a 19th-century convention). In recent years, low-cost Chinese production and environmental concerns have caused suppliers outside of China to shut down operations.
Alternatives to rare earths exist for some technologies. One example is the induction motor used by Tesla Motors in its all-electric Roadster. It uses electromagnets rather than permanent rare-earth magnets. But such motors are larger and heavier than ones that use rare-earth magnets. As a rule of thumb, in small- and mid-sized motors, an electromagnetic coil can be replaced with a rare-earth permanent magnet of just 10 percent the size, which has helped make permanent magnet motors the preferred option for Toyota and other hybrid vehicle makers. In Tesla’s case, the induction motor technology was worth the trade-off, giving the car higher maximum power in more conditions, a top priority for a vehicle that can rocket from zero to 60 mph in 3.7 seconds. “The cost volatility going into the rare-earth permanent magnets was a concern,” says JB Straubel, Tesla’s chief technology officer. “We couldn’t have predicted the geopolitical tensions.”
More manufacturers are following Tesla’s lead to shun the rare-earth materials, although the move means sacrificing space and adding weight to vehicles. A week after the China dust-up began, a research team in Japan announced that it had made a hybrid-vehicle motor free of rare-earth materials, and Hitachi has announced similar efforts. BMW’s Mini E electric vehicle uses induction motors, and Tesla is supplying its drive trains to Toyota’s upcoming electric RAV 4. Given the volatility of rare-earth supplies, and the advantages induction motors offer in high performance applications, “It makes sense for car companies to give serious thought to using induction motors,” says Wally Rippel, senior scientist at AC Propulsion. Rippel previously worked on induction motor designs at Tesla and GM, where he helped to develop the seminal EV1.
As automakers explore alternative motors, researchers in the U.S. and elsewhere are also trying to devise replacements for rare-earth materials, and political efforts are advancing to boost supplies of rare earths from outside of China.
In the U.S., the Chinese dominance of rare-earth mineral production has prompted a surge of funding focused on developing permanent magnets that use less, if any, rare-earth materials, such as nearly $7 million from the Advanced Research Projects Agency for Energy (ARPA-E). In one of these projects, University of Nebraska researchers are working to enhance permanent magnets made with an alloy iron and cobalt, or FeCo. This class of materials is sold today, but delivers half or less of the power of the best rare-earth-based magnets. The Nebraska researchers will focus on ways to dope the structural matrix of these alloys with traces of other elements, thereby rearranging their molecular geometry to create stronger, more durable permanent magnetic materials.
Working alongside the Nebraska researchers in the same ARPA-E program, researchers at the University of Delaware are advancing nanocomposites that use far less of the valuable rare-earth materials, but that have been shown theoretically to generate magnetic strengths twice as powerful as today’s best permanent magnets. The lab is mixing particles, just 20 to 30 nanometers in size, of rare-earth magnetic materials with a non-rare-earth complement (tin cobalt). Prior efforts to make this material have been unable to precisely align the nanoparticles, diminishing their magnetic performance substantially. Instead of concocting the material in bulk, like mixing batter, the team is developing a process to control the particles’ alignment by assembling them in regular arrays.
GE Global Research, in Niskayuna, New York, is pursuing nanocomposites similar to those being developed in Delaware, also with ARPA-E funding. Using methods developed in-house, the project aims to build a new material through the alignment of nanopowders. “These materials are intrinsically unstable,” so controlling their assembly is at the frontier of nanoscale manufacturing processes, says Luana Iorio, a manager at GE’s High Temperature Alloys and Processing Laboratory, who leads the research. GE estimates its nanocomposites could deliver 35 percent greater magnetic strength than today’s best permanent magnets, while using 40 percent of the rare earths, by volume. Within two years, Iorio hopes, the project will be able to create samples of the new material a few centimeters in diameter.
Yet since it may take years for these efforts to bear fruit, the hunt for non-Chinese sources of the minerals is attracting attention in the near term. In California, Molycorp Minerals is looking to reopen rare-earth mines that closed in 2002, amidst low pricing and environmental concerns. In recent weeks, bills have been floated in the U.S. House and Senate aimed at reviving the rare-earth supply chain in the U.S., including mining, refining, and manufacturing. A third bill, in the House, is narrower, focusing on offering loan guarantees to restart mining.