Cleantech Market Intelligence
Hyperloop Faces Technical Hurdles
If a prototype of the Hyperloop – Elon Musk’s futuristic superfast train – ever gets built, it will have to overcome some very significant engineering challenges that may or may not be solvable. After reading through the published document that explains how the concept works (it reads something like a cross between a patent application and a Popular Science article), I can’t say that it will or it won’t work. But I do have opinions on the plan’s strengths and weaknesses.
I should point out that, while I’m not an engineer, I have helped design systems that use compressed air and deal with the aerodynamics of large structures. I’ll start with my opinion of what the plan has going for it, followed by important challenges that still require a solution.
The most important element of the concept paper is that it doesn’t really invent anything. Everything described in the plan has been built for other applications and proven to work. The electric engine and battery pack would be variations of what Tesla has built in the Model S. The steel tubes, through which the passenger pods would travel, would be carefully aligned versions of pipeline tubing. The compressor on the front of the pod would be similar to any industrial compressor.
Not So Outrageous
Every entrepreneur claims that his or her idea will be cheaper than the currently available technology, and just about every entrepreneur turns out to wildly overestimate how cheap his or her system will be. Musk’s paper does an excellent job of detailing exact pricing of each element of the project so that there’s no magical thinking involved in the pricing expectations.
Musk began this project when he realized how awful high speed rail is as a transportation solution. Although we’re comfortable with trains, few of us really appreciate how much it costs to build a brand new rail line. The $68 billion price tag for California’s rail project seems outrageous, but it’s actually not too expensive in the world of high-speed rail. It’s worth considering that perhaps the craziest option is to spend $68 billion on a more conventional alternative to the Hyperloop.
The biggest concern with this plan has to do with temperature. The pod will be compressing air and expelling it downwards and backwards. All that air compression creates an enormous amount of heat, which can damage the pod and its machinery. Musk’s solution is to add to each pod a water tank that will capture that heat and turn it into steam to be collected at the next station. Although the thermodynamic calculations are correct, a small pod with only a few cubic feet of room for a heat exchanger leaves little space for an efficient exchange of heat. That means that the flow of water must be increased, requiring a lot more water on board. There may be an elegant solution for this challenge, but it’s not in Musk’s current paper.
Wind stress is another challenge. Any structure elevated 100 feet off the ground is going to be under a lot of wind pressure, which will act on it in weird and sometimes multiple directions. If that structure is a heavy tube stretching hundreds of miles in either direction, you effectively have a big sail. Will the concrete pylons be powerful enough to resist that pressure?
The Hyperloop may or may not ever get built, but there are few examples of a billionaire spending his own time and money on giving the world a unique idea that’s been well thought-out and clearly worth investigating further. Musk’s vision and audacity should be applauded.