1
$\begingroup$

I'm refining my previous question about magnetic levitation trains on Mars. In my story, set on Mars, two settlements are connected by a railway line. Currently, it is an ordinary train of the type most common today on Earth. But I'm now considering whether a maglev train might be better. So the question is:

How much energy does a maglev train consume compared to an ordinary train?

Some details of the context:

  • The story takes place in a 100-year far future.
  • There are only the first few permanent human settlements, including these two. The oldest and largest of these has 1'500 inhabitants, the other - 570.
  • Settlements are separated by 1'000 km.
  • Train is (currently) travelling this distance in 6 (six) hours and runs once an hour throughout the day. So, someone who needs to get to the other settlement by 6:00 AM takes the midnight train.
  • Train and the tracks are significantly wider than on Earth as they have no reason to follow Earh's standard, but lower gravity affects stability.
  • A passenger train is usually one cart of similar capacity as most current-day train carts. Cargo carts are also the same capacity.

I'll link any useful resources I find elsewhere in my own answer.

Improve this question
$\endgroup$
12
  • 2
    $\begingroup$ Since you got no answer yet on the other one, why don't you edit that one instead of reposting? $\endgroup$
    – L.Dutch ♦
    Commented May 3, 2023 at 10:59
  • $\begingroup$ @L.Dutch To keep the research record. I want to be able to review later the way I was thinking and investigating my questions. $\endgroup$
    – Krišjānis Liepiņš
    Commented May 3, 2023 at 11:05
  • 1
    $\begingroup$ WoW stands for Way of Working. I see that you are splitting the old questions into individual ones. I have deleted the old one $\endgroup$
    – L.Dutch ♦
    Commented May 3, 2023 at 11:24
  • 1
    $\begingroup$ I don't really see the utility of a maglev system here. They are incredibly capital intensive to build, and lack the versatility of ordinary tracks in terms of track switching, etc. The only realistic application of a maglev are between two heavily trafficked areas requiring extremely high passenger volumes. At least one of those criteria don't apply. Especially at 1,000km distances, I can think of a myriad of better transportation methods (barges, aircraft, conventional HSR) that don't require the resources that maglev needs. $\endgroup$
    – dreamforge
    Commented May 5, 2023 at 19:59
  • 1
    $\begingroup$ @dreamforge Over the hundred years between today and the time of my story, the capital intensity of building maglev lines surely would have dropped significantly? Regarding the versatility, do you mean maglev tracks don't allow joining two lines as railway tracks do? $\endgroup$
    – Krišjānis Liepiņš
    Commented May 6, 2023 at 7:09

2 Answers 2

Reset to default
2
$\begingroup$

Maglev is an inefficient technology. It's great if you want to move a small amount of something super fast (high speed passenger rail) but for commercial operations the energy required to levitate tens of thousands of tons of non-perishable bulk goods is an entirely unnecessary additional cost, for at best a marginal benefit.

Compared to highspeed passenger rail, maglev passenger rail consumes roughly twice the power per passenger kilometer.

This site gave a figure of 0.4 MJ/passenger-mile (0.6 MJ/passenger-km) for maglev
This site gave a figure of 0.35 MJ/passenger-km

For commercial freight I found an efficiency figure of 520 ton-miles per gallon (660 kg-km/MJ). Assuming 70kg for the average commuter passenger this gives us an efficiency of (116 kg-km/MJ) for maglev.

Improve this answer
$\endgroup$
4
  • $\begingroup$ It's worth noting that, at least in France, freight trains have priority over passenger trains precisely because it takes so much more energy to launch a freight train that you never stop one if you don't positively have it. $\endgroup$
    – AmiralPatate
    Commented May 3, 2023 at 14:11
  • $\begingroup$ Weard, I read the same article and got the opposite impression. Did you see that table comparing ICE 3 (a wheel-on-rail train) and Transrapid (maglev train ), or not? $\endgroup$
    – Krišjānis Liepiņš
    Commented May 3, 2023 at 21:40
  • $\begingroup$ The ICE 3 vs Transrapid table compares the efficency of transporting a square meter of passenger space. Using the passenger kilometer figure gives us a better unit of comparison to other passenger rail efficiency numbers, and allows for an approximate comparison with freight rail efficiencies. $\endgroup$
    – sphennings
    Commented May 4, 2023 at 2:56
  • $\begingroup$ @sphennings Passenger kilometre figure depends on the comfort level particular operator requires. Thus with the same type of train, the operator requiring a higher comfort level would spend more energy per passenger than an operator requiring a lower comfort level. Comparison on effective area avoids this bias. $\endgroup$
    – Krišjānis Liepiņš
    Commented May 5, 2023 at 6:19
1
$\begingroup$

Depends on the kind of magnets you use

When most people think maglev trains, they think electro magnetic levitation that can be turned on and off. These consume much more power than a traditional train... however, using ferromagnetic levitation, you can make a train that is 8.3 times more efficient to operate than an EM-Maglev train or 4.8 times as efficient as a normal train to in Earth like conditions.

With a traditional train, you have a wheel that is pressed into the track by gravity. The harder this force becomes, the more resistance you get with the track that has to be overcome when moving.

However, with a ferromagnetic lev train, there is no friction at all. Putting more weight on the train just presses the magnets closer together which increases thier repulsion. The only point of contact may be between rollers and the sides of the track as your train turns and needs to be reangled, but on straight-aways, there is no friction at all.

enter image description here

Also, of note: The advantages of lev trains are amplified in a low atmosphere environment like Mars. Trains on Earth receive some resistance from the track, and some from the air, on Mars nearly all resistance will be from the track; so, reducing this to zero while also having near zero air resistance will allow a train, once up to speed, to move for incredible distances with very little additional input, and once you get there, most of your power it took to get you up to speed can be recovered through a breaking power recovery system. Such a system on Mars could be 10s if not 100s of times more power efficient than a traditional train.

Your actual acceleration can be done in many ways, but the way currently be considered for such maglevs would be to add a weaker electromagnetic 3rd rail. This could be engaged just for speeding and slowing using alternating poles just like a normal mag-lev train and turned off to conserver power by coasting once you are up to speed.

Improve this answer
$\endgroup$
9
  • $\begingroup$ Do you mean the train hanging down from the track? $\endgroup$
    – Krišjānis Liepiņš
    Commented May 3, 2023 at 16:35
  • $\begingroup$ @KrišjānisLiepiņš more like pressed up into it... but essentially yes. You make permeant magnets strong enough to repel the train + cargo; so, any load less than max will result in an upward force into the track... so the train becomes effectively lighter, the more you load it up. $\endgroup$
    – Nosajimiki
    Commented May 3, 2023 at 16:54
  • $\begingroup$ You can then optionally adjust the hydraulics on the wheels to create a distance between the magnets until it approximately zeros out based on your current load. $\endgroup$
    – Nosajimiki
    Commented May 3, 2023 at 16:58
  • 1
    $\begingroup$ you side magnets can also be your propulsion magnets. One weird downside you don't have to worry about on earth, there is a LOT of iron dust in Martian dust which will build up on ferromagnets. $\endgroup$
    – John
    Commented May 3, 2023 at 23:59
  • 1
    $\begingroup$ @jdunlop depending on oxidization state iron oxide is still attracted to a ferromagnet. only FeO is not, Fe3O4 and Fe2O3 are magnetic and are both common on mars. $\endgroup$
    – John
    Commented May 4, 2023 at 20:44

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .