The opening ceremony of each Olympic game is filled with pageantry and sometimes, with the lighting of the cauldron, drama. In my mind the most electrifying occured in the 1992 Barcelona games when Paralympian Antonio Rebollo performed some serious diablerie.
Across the ocean in New Providence, New Jersey David and Mary watched the scene on a small black and white television as they shared pedaling duties. David was pedaling at the time and gasped. Fortunately there was a flywheel.
Their parents didn't allow television in the home, but both of them had been involved in competitive kayak and canoe events. Lynn had been an alternate for the Montreal Olympics. Introducing Mary and David to the Olympics was a good idea, but Al decided to make it educational. The kids would be given an exercise bike, a generator, access to a television and help from their mechanical engineer father and mathematician mother. They had a few weeks to work things out.
When the the friction wheel generator was finally adjusted and working, they were shown how much power they produced and how much power various televisions used. A twelve year old could keep a small color set going for a short time, but that was it. They wisely chose the black and white set. Through trial and error they ended up with a bicycle chain transmission and abandoned the exercise bike for one of their own on a homemade stand. They could now produce nearly twice the power for the same amount of perceived work. A flywheel was added to make everything smoother. They had something by the opening ceremony and the kids spelled each other off and developed an amazing sense of how long the commercials lasted. They saw the torch lighting.1
It's too bad they had a standard generator. Something with better magnets would have had increased efficiency. Not enough to move them into a color set (if they were a few years older and more athletic they probably could have managed), but certainly a better experience. The strength of the magnetic field in a generator or motor is centrally important. The strongest fields come from superconducting magnets, but they need to be cooled to near absolute zero rendering them impractical for most applications.
Electric vehicles use either induction or permanent magnet motors. The permanent magnet designs tend to be lighter and are more efficient.2 There's a rub. You're trying to optimize cost and magnetic field strength (among other things). Rare earths like neodymium work much better than the cheaper ferrite-based magnets and have generally taken over the medium and high end automotive market.3
The problem with rare earth materials isn't that they're rare .. they fairly comment. They are, however, unevenly distributed and difficult and toxic to mine and process. Most of the active mining and processing is in China and it's an environmental disaster. The US had a single mine in California in the fifties. Since then it's had t an up and down existence including being closed for economic and environmental reasons. With the interest in EVs it's back in operation again and the US has gone from 0% of the world's production of neodymium to about 15% in about seven years. In theory the mining and processing and safer and less toxic than the Chinese effort. Production should increase in the future. The US is also largely unexplored - serious mineral exploration has only just resumed after a 60 year hiatus.
The higher cost has some companies, notably Tesla, talking about going to ferrite permanent magnets. They'd be heavier, less efficient, but would be cheaper and may be the core of lower-end vehicles. Another alternative is to use a more efficient vehicle. Electric bicycles and other micromobility solutions use small motors. You can build 50 to 200 electric bike motors with the materials from one Tesla-class motor. Not only that these vehicles are very practical for the short trips that dominate much of our mobility needs. Sadly some areas have saddled themselves with transportation infrastructures that encourage inefficiency.
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1 Mary continued in the families sport tradition and went to Princeton on a fencing scholarship. She found she was interested in aeronautical engineering and went on for a Ph.D. I heard she had something to do with the rotor design on the Ingenuity helicopter currently flying on Mars.
2 There are often questions about how permanent magnets work. Most people have seen electromagnetic induction in school. A current flows if you move a magnet in a coil of wire and a current through a wire produces a magnetic field. Permanent magnets are more difficult to talk about .. I've done it at least once, but this short video is a nice intro.
3 There are other rare-earth based magnets, but a neodymium alloy is the most common. It's an allow of neodymium, iron and boron - Nd2Fe14B - that forms a crystalline structure. They have widespread use outside of EVs.. GM and Sumitomo Metals independently developed them about 40 years ago to get away from much more expensive and brittle samarium–cobalt magnets.
There's a lot of talk about tetrataenite (an iron-nickel structure) permanent magnets. In theory they have better magnetic characteristics than neodymium alloys and should be much cheaper, but they're off in the future. If they happen, expect some unhappy rare earth mining companies.
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