Fast Trains Are Energy Efficient (And Fast)

Cars and planes make sense for short and long distances, but for intercity travel, they don’t even come close to fast trains

2 min read
Photo-illustration by Stuart Bradford
Photo-illustration: Stuart Bradford

I have no animosity toward cars and planes. For decades I have depended for local travel on a succession of reliable Honda Civics, and for years I have flown intercontinentally at least 100,000 miles annually. At these two extremes—a drive to an Italian food store, a flight from Winnipeg to Tokyo—cars and planes rule.

Energy intensity is the key. When I’m the only passenger in my Civic, it requires about 2 megajoules per passenger-kilometer in city driving. Add another passenger and that figure drops to 1 MJ/pkm, comparable to a half-empty bus. Jet airliners are surprisingly efficient, commonly requiring around 2 MJ/pkm. With full flights and the latest airplane designs, they can do it at less than 1.5 MJ/pkm. Of course, public-transit trains are far superior: At high passenger loads, the best subways need less than 0.1 MJ/pkm. But even in Tokyo, which has a dense network of lines, the nearest station may be more than a kilometer away, too far for many old people.

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A photo shows separated components of the axial flux motor in the order in which they appear in the finished motor.
INFINITUM ELECTRIC
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The heart of any electric motor consists of a rotor that revolves around a stationary part, called a stator. The stator, traditionally made of iron, tends to be heavy. Stator iron accounts for about two-thirds of the weight of a conventional motor. To lighten the stator, some people proposed making it out of a printed circuit board.

Although the idea of replacing a hunk of iron with a lightweight, ultrathin, easy-to-make, long-lasting PCB was attractive from the outset, it didn’t gain widespread adoption in its earliest applications inside lawn equipment and wind turbines a little over a decade ago. Now, though, the PCB stator is getting a new lease on life. Expect it to save weight and thus energy in just about everything that uses electricity to impart motive force.

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