Building a car like the Toyota Prius hybrid, for example, requires 20 to 25 pounds of rare earths, about twice as much as a standard automobile. A Prius contains more than two pounds of neodymium, just one of a handful of these metals found all around the vehicle, including the battery pack.
The Chinese government’s recent efforts to curb exports of rare earths have sent prices skyward, spurring interest in electric motors that rely less on permanent magnets to create roadworthy propulsion.
One such technology, called switched reluctance, might offer a viable alternative. It uses a steel rotor that spins freely inside a housing of wires. Controlled by complex algorithms and solid-state switchgear, the motor can turn at variable speeds and at high torque levels.
“Essentially, you can get the same type of performance without needing to use rare-earth magnets,” said Scott Nieberle, a vice president at Nidec Motor Corporation, a switched-reluctance motor manufacturer based in St. Louis.
Although switched reluctance motors are not new, their commercial viability has steadily increased in the past 30 years with the improvement in modern electronics. They are commonly found today in large mining machines, water-treatment plants and other industrial applications. Washing machines and other household appliances use reluctance motors. Earlier this year, John Deere introduced two diesel-electric hybrid construction loaders equipped with switched-reluctance motors and generators.
Nidec Corporation, the Japan-based parent of Nidec Motor, owns nearly 500 patents in this area and has motors running on industrial machines worldwide. The company hopes to boost its presence in the hybrid automotive space, and claims it would not take much to make these motors cost-competitive with higher-volume magnet motors.
“You could do reasonable economies of scale when you get into the tens of thousands of units, on an annual basis,” said Mr. Nieberle. Nidec Corporation showed a demonstration car based on a Japanese-market sports car, theTommykaira ZZ, to investors in May in Dalian, China.
“There was a lot of interest,” said Mr. Nieberle.
The car’s switched-reluctance motor spins at 11,000 r.p.m., propelling it to highway speeds. Green Lord Motors, a Japanese start-up, plans to market the car this year.
Another company, Belgium-based Punch Powertrain, is developing its own switched-reluctance motor for electric cars. However, this technology is just one of several that automakers are exploring to lighten their rare-earth baggage, experts say.
“There are a number of options on the table,” said Philip Gott, the managing director of IHS Automotive, an industry forecasting service based in Lexington, Mass., who added that it could take a decade for automakers to settle on the next-best motor composition for their electric powertrains.
And even if rare earths are dropped from the motors, suppliers still face the challenge of the batteries, whose chemistry is still a moving target.
“We still have significant gains to make,” Mr. Gott said.