Where there’s tech, there’s magnets. The strong magnets that generate their own magnetic field, AKA permanent magnets, aren’t only on your fridge. They’re in multiple places inside your fridge, and in your cell phone, headphones, and hard disk drive, too. Permanent magnets are also a critical resource for renewables, because the generators in some wind turbines and motors in electric vehicles rely on them to run.
This is far from ideal, though. Most permanent magnets are made of what we call rare-earth metals, and these elements are difficult to mine, expensive, and not widely recycled. Processing rare earths creates radioactive waste. Plus, the vast majority — over 90% — are sourced from China alone, creating supply risks. As a result, the elements most crucial to clean energy are ironically the most unsustainable.
But what if we could avoid using them altogether … and potentially make a better electric motor? With his design for a permanent magnet-free electric motor, a Floridian high school student has just shown us how. Another company is using cloud computing to try to improve electric motor performance — also without rare earths. There’s some exciting advances being made when it comes to electric motors, but how much of a difference can they make?
In his own words, 17-year-old Robert Sansone of Fort Pierce, Florida has “a natural interest in electric motors.” While researching electric vehicles one day, he learned about the negative environmental impacts of the rare-earth elements used in the permanent magnet motors that power them.1 This sparked his interest in developing an alternative type of motor without rare earths.
But first, what are these rare-earth elements, and why are they so problematic? Well, 17 elements of the periodic table are considered rare-earth elements or rare-earth metals, AKA REEs.2 To clarify, REEs aren’t really “rare” in terms of crustal abundance so much as rarely found in quantities large enough to justify mining.3 However, we’re surrounded by REEs every day. These elements are highly conductive to electricity and used in a huge number of technologies, from fighter jets to fiber optic cables. Glass and ceramics are another primary application, and they represented about 10% of the end-use distribution of REEs in the United States in 2021.4
Rare earths are used extensively in the automobile industry, whether in the catalytic converters of cars or the rechargeable batteries of hybrid vehicles. Some act as stabilizers in the process of turning oil into gasoline.453 And when it comes to permanent magnets, neodymium and dysprosium in particular are vital. In fact, according to the United States Geological Survey, neodymium-iron-boron magnets are the most powerful we’ve got. These magnets can withstand temperatures as high as 230 C, and they’re especially advantageous in clean energy tech because they allow gearboxes to be eliminated in wind turbines and electric cars.36 To put the use of neodymium into perspective, a single 1 MW wind turbine needs about 700 kg of it for the turbine’s magnet-based generator to function.75
As the demand for REEs continues to skyrocket, their concentration in the hands of a few suppliers is becoming more and more of a concern. Pini Althaus, CEO of USA Rare Earth, estimated in a 2021 interview that the United States would need to produce around 20 to 25 times more rare earths than it already does to lessen our near-total reliance on China between now and 2050.8
However, REE production is a costly, difficult process that has serious consequences. Rare-earth metals never occur as free elements, but instead as mixtures in ores. They have to be purified to be used, and the process of separating REEs can involve thousands of steps and massive amounts of harsh chemicals. This is made even more complicated by the fact that all REEs require different chemical techniques for refining.3 Also, the ores and minerals that REEs are primarily sourced from naturally contain uranium and thorium. This means that producing REEs creates a significant amount of toxic and radioactive wastes.9
To make matters worse, products containing REEs (like smartphones, monitors, and LEDs) are usually dumped into the trash, not recycled.10 Attempting to salvage valuable metals from this e-waste can be extremely dangerous to human health anyway because consumer electronics typically contain harmful substances like lead and mercury.11
All these factors translate into the priciness of REEs. Some elements, like neodymium and gallium, go for hundreds of dollars per kilogram. Others, like hafnium and germanium, will run you thousands of dollars per kilogram.12 Meanwhile, copper hovers at about 8 bucks per kilogram.13
So, despite their usefulness, rare-earth elements complicate our relationship to renewable energy. If the permanent magnets that set EVs in motion come at such a high cost, then what are our other options? When Sansone continued his research to answer this question, he discovered that synchronous reluctance motors don’t use permanent magnets. The thing is, synchronous reluctance motors don’t provide nearly as much efficiency or torque, so they normally wouldn’t work in an EV. Motivated by the opportunity to use this research as a project for school, Sansone began a yearlong quest to fix that.1
To understand what Sansone eventually accomplished, let’s lay out what an electric motor is and where permanent magnets come in. Electric motors are everywhere: if an object moves, chances are an electric motor is driving it. That’s why it’s no surprise that electric motors are responsible for 43% to 46% of the world’s electricity consumption.14
An electric motor works by converting electricity into mechanical energy. When an electric current flows through a coil within a magnetic field, a force is generated that in turn produces torque.1516 Torque is what causes an object to rotate about an axis, and when torque is applied to a motor, it spins.17This rotation is then transferred from parts like gears to whatever needs to move, like a fan’s blade, a car’s wheels, or your vacuum cleaner.18
The core of an electric motor is its electromagnet. It takes the form of a metal loop called an armature, which, once connected to a current, essentially becomes a big flat magnet. Like any other kind of magnet, it has a north pole and a south pole. These can be flipped by reversing the polarity, which really just means some control electronics are swapping which wires are charged to the positive and negative ends of the battery. In a direct current or DC motor, curved north and south pole magnets on opposite sides of the armature make up a stator, or static permanent magnet.
The armature will spin to align with the stator’s magnetic poles, but when we reverse the polarity, it continues spinning to align to the new north on the opposite side. Reversing the polarity back and forth causes magnet to keep spinning as it tries to stay aligned, which in turn creates mechanical energy.18
DC motors have been in use since the mid-1800s, but alternating current or induction motors are preferred in 70% of industries.19 In DC motors, flip-flopping the polarity of the inner rotor causes it to spin. In an AC motor, made famous by everyone’s favorite scientist, Nikola Tesla, power is sent to paired coils positioned along the stator to produce a magnetic field in the rotor, which is affectionately referred to as a squirrel cage.20 These coils are charged in a rotating phase sequence, essentially creating a swiftly rotating magnetic field. The magnetized rotor then spins as it tries to “catch up” to the field flowing around the stator. This can be measured as the saliency ratio, which is how efficiently a rotor aligns with the applied magnetic field before the coils change their charge. Because this process is called induction, AC motors are also referred to as induction motors.18
Enter Sansone, who zeroed in on synchronous reluctance motors (SynRM) precisely because they don’t use magnets or rare earth metals. Instead, they just use a charged steel rotor with air gaps cut into it. Just like other electric motors, the rotor spins along trying to align with the rotating magnetic field. But as Sansone has explained, what makes a synchronous reluctance motor special is its air gaps, which create an exploitable difference in magnetic reluctance.
Magnetic reluctance is equivalent to magnetic resistance. Metals with high magnetic reluctance move more as they try to resist a magnetic field. Per Sansone’s description, maximizing the difference between the low magnetic reluctance of the steel rotor and the high magnetic reluctance of the slots cut into it increases the motor’s saliency ratio. Higher saliency means higher torque.21
Still, neither the torque nor efficiency of synchronous reluctance motors, or SynRMs, are currently enough for EVs. Therefore, Sansone’s goal was to improve upon these relative weaknesses in hopes of designing a SynRM that could compete with permanent magnet ones. Then, by switching to these motors, we could theoretically make EVs both much more sustainable and cheaper.21
Armed with a 3D printer, steel, and copper, Sansone spent a year optimizing his concept for a novel SynRM.1 Over the course of building 15 prototypes, Sansone developed his motor without air gaps, instead incorporating another magnetic field in their place. This one tweak gave the exploitable resistance and saliency ratio of the motor a big boost, producing 39% more torque and operating 31% more efficiently at 300 revolutions per minute. The efficiency jumped to 37% when the motor ran at 750 RPM, but any higher and Sansone’s 3D-printed plastic parts would overheat. One prototype actually melted on his desk.1
Fortunately, this loss was not in vain. In May, Sansone received first prize at the Regeneron International Science and Engineering Fair for his SynRM, heading home with $75,000 for his efforts. He hasn’t stopped, either: as of October, he was still working on the 16th iteration of his motor, with plans for version 17 underway.21
We can only say so much about the viability of Sansone’s design for two reasons. For one thing, he intends on patenting his SynRM, so he hasn’t shared specifics about how it works. And as Sansone points out himself, a Tesla motor can reach 18,000 RPM. It simply isn’t possible for him to test the relative power of his heat-sensitive prototypes with the resources he has.21 In any case, Sansone’s story is an impressive show of what’s possible.
Synchronous reluctance motors are an upcoming potential pathway to addressing the sustainability issues caused by REEs. Switched reluctance motors, however, are already in motion. Like SynRMs, switched reluctance motors, or SRMs, sidestep magnets entirely. They both start with the same letters and lack permanent magnets, so it’s a little confusing, but they work differently.
On a superficial level, SRMs function similarly to three-phase induction motors, a type of AC motor. An SRM works by wrapping magnetic steel in copper, with a similarly magnetic steel and copper-coil rotor.22
That might not sound like it makes a difference, but it does. The magnetic forces exerted on the iron in a SRM’s rotor can be up to 10 times greater than the magnetic forces on the current-carrying conductors.23 And with no magnets or winding on the rotor, they’re even more fault tolerant than the already rugged three-phase induction motors.22
Why aren’t SRMs used more widely? You can blame that on some significant drawbacks, including how loud they are. Though SRMs are powerful, they’re not very efficient. They aren’t as smooth as three-phase induction motors. They vibrate, and they display more severe torque ripple, or variations in torque as the shaft rotates.24 And managing the charged steel components also requires more advanced control and monitoring methods than other types of electric motors.
With all these issues in mind, Turntide Technologies is attempting to tackle our need to reduce energy consumption through its Smart Motor System. Using SRM technology, the company’s system is made up of a motor, its controller, and the cloud. The system collects data from the different parts of the motor to determine the ideal motor speed, and stores analytics for both the controller and the user in the cloud. The idea is to ensure the motor operates at optimum efficiency at all times so that no power is wasted.
That’s a big deal considering the sheer number of electric motors running at any given time. According Turntide CEO Ryan Morris, if we were to replace the motors in every building on earth with smart motors, we could reduce global carbon emissions by 2.3 gigatons a year, or what he calls the equivalent of growing seven more Amazon rainforests.25 That’s a bold claim that you should take with a giant grain of salt, but the smart motors’ performance in the HVAC system case studies available on Turntide’s website is promising.
In one pilot program, Canadian real estate company Ivanhoé Cambridge retrofitted the HVAC systems in two malls with Turntide’s smart motors. These locations saw 38% and 35% in energy savings and 79% and 64% decreases in motor energy usage, respectively.26 The British retail chain Wilko similarly tested 800 motors across 400 stores. The company saw 40% in energy savings alongside an additional 20% in savings when coupled with building automation.27 Overall, when used in HVAC systems, Turntide’s smart motors promise to pay for themselves in less than three years.28
Sansone’s synchronous reluctance motor and Turntide’s switched reluctance motor are great examples of “when there’s a will, there’s a way.” And in Sansone’s case, it gives me a lot of hope for the future of budding engineers out there. Even as we face the destructive effects of manufacturing permanent magnets, we have pathways ahead of us to help fix that problem. Rare-earth elements might be ubiquitous in the clean energy sector at the moment, but may not have to be.
- This 17-Year-Old Designed a Motor That Could Potentially Transform the Electric Car Industry ↩︎
- Rare-earth element ↩︎
- Rare Earth Elements ↩︎
- Rare Earths ↩︎
- Critical Mineral Resources of the United States—Economic and Environmental Geology and Prospects for Future Supply ↩︎
- How Are Magnets Used In Wind Energy? ↩︎
- Permanent Magnets – Research for Sustainability ↩︎
- Neodymium, praseodymium, dysprosium, terbium: Key blockers to EV ascendancy ↩︎
- TENORM: Rare Earths Mining Wastes ↩︎
- Rare Earth Recycling ↩︎
- Soaring e-waste affects the health of millions of children, WHO warns ↩︎
- Current Strategic Metals Prices ↩︎
- Copper Price ↩︎
- Electric Energy Consumption ↩︎
- Electric motor ↩︎
- What is an electric motor? ↩︎
- Torque ↩︎
- How Electric Motors Work ↩︎
- Advantages & Disadvantages: Induction Motor ↩︎
- How Do Electric Motors Work? ↩︎
- 17-Year-Old Designs Greener Motor That Could Revolutionize EVs ↩︎
- The Turntide Technologies Switched Reluctance Motor ↩︎
- Everything About Switched Reluctance Motor ↩︎
- Torque ripple minimization in switched reluctance motor drives by PWM current control ↩︎
- Turntide Technologies reinvents the motor ↩︎
- Smart Buildings Customer Case Study: Ivanhoé Cambridge ↩︎
- Wilko: Reduced energy usage by 60% ↩︎
- HVAC Rooftop Units (RTUs) ↩︎