Hybrids, EVs face new challenge: the possible rarity of rare earths

  • 19-Jul-2010 03:55 EDT
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A rare insight into the use of rare earth metals in a vehicle.

The complexities of developing a global hybrid and plug-in electric vehicle society are massive in terms of design, safety, production, and infrastructure. But an area that is now receiving increasing attention concerns rare earth metals, essential for high-power, lightweight magnets used in electric vehicles and for battery applications.

Ironically, at present rare earth metals (the Lanthanide series together with yttrium and scandium) are not particularly rare, but they might become so as demand for them grows, according to a new report produced by environmental and research consultancy Oakdene Hollins for the U.K. Government’s Department for Transport. The danger of demand outstripping supply in a few years as fossil fuel reduction programs gain momentum is a reality that the auto industry cannot ignore.

Demand is expected to grow by about 8-11% per annum from 2011 through 2014, with magnets and metal alloys for hybrid and electric vehicles responsible for most of it. Although total world supply is forecast to exceed world demand for that period, shortages are expected to be experienced in the future for key heavy elements such as dysprosium and terbium, warned Dr. Hüdai Kara, one of the authors of the Oakdene Hollins report.

Small amounts of rare earth elements are found in many automotive components, from small motors to auxiliary systems, but far more in hybrids for electric motors and generators—neodymium to make neodymium-iron-boron (NdFeB) magnets, plus smaller quantities of praseodymium, dysprosium and terbium—and NiMH (nickel metal-hydride) batteries—lanthanum and to a lesser extent cerium.

Many NiMH batteries use battery-grade mischmetal rather than pure lanthanum and cerium. A Toyota Prius battery takes 1 kg (2.2 lb) of neodymium and 10 to 15 kg (22 to 33 lb) of lanthanum, said Kara.

Although new mines for the metals are scheduled to be opened in several countries including the U.S. in 2014, by far the main supplier is, and will continue to be, China, at present producing more than 95% of total world production (124,000 t).

As demand grows in sympathy with the expansion and acceptance of the global EV fleet, pressure on the Chinese mines will increase, causing OEM worries about shortages of supply. Another potential concern is the strategic and political aspects of a near-monopoly supply source.

Kara explained: “China is expected to remain the world supplier because of the time required to develop resources in operational mines. Despite new mines opening in the next few years, supply of rare earths for particular elements may be tight over the medium term.

“China’s draft ban of the export of rare earths from 2015 is consistent with concern that it is likely to continue to limit exports of rare earth metals. China’s strategy is to encourage the manufacture and export of higher value goods—magnets, motors, batteries—which incorporate rare earths.”

Non-Chinese companies may choose to invest in or contract for the manufacture of those goods in China or seek to develop non-Chinese supply chains, the report states. But it warns that intellectual property rights, environmental liabilities (and image), and supply risk management mean that many non-Chinese companies will seek to develop alternative supply chains.

There is some positive news. Current estimates of world reserves stand at 99 million t (109 million ton). Although mostly in China, in other areas up to four new mines are scheduled for production. As well as the U.S., Canada and Australia will also have them. And the Commonwealth of Independent States has reserves.

Technologies other than transportation-related also need rare earth metals. These include magnet-based generator wind turbines for energy generation.

Specialists within the auto industry are looking for alternative technologies that eliminate or at least reduce the quantity of rare earth metals in EV motor magnets, said Kara. “But those are limited. Reduction is likely to be achieved through the minimization of rare earths usage in existing magnetic materials or through the adoption of entirely new varieties of electric motor. However, lithium-based batteries are already a viable alternative to current NiMH batteries for hybrid vehicles.”

Recycling rare earths from batteries has been examined by specialists in Japan, but at present there is no commercial recovery process because cost-yield ratios make it uneconomical.

Meanwhile, the Oakdene Hollins report recommends that the U.K. Government supports application-focused development of rare-earth magnets and of whole-life cycle management of the systems within which they are used, possibly in collaboration with the European Union, U.S., and Japan.

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