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Comment by TylerE | Hacker News Reader

I just don't see it. It's just such a pain in the ass to store and handle. Locomotives are actually a better case for batteries than most, because you could keep the batteries in a secondary car, much like a steam locomotive tender, that can easily be swapped out on a siding when needed in about 10 minutes... or just chain as many together as you need for the trip.

Trains, especially freight trains, aren't that weight sensitive, since they tend to mostly roll along at the same speed.

Such trains could be fitted with a pantograph and operate directly off OHLE when possible. Actually, don't recall the class but I'm fairly sure the UK has a variant of one it's commuter EMU with a small built in batter. The route it travels has a few miles without wires where is impractical to add wires so it uses batterys to cover that gap.

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Not being weight sensitive is the very important key point. It means trains of the future could use some non-lithium battery chemistry.

Likely sodium-ion, which is projected to be significantly cheaper due to abundant materials, safer due to its chemistry, more tolerant to hot/cold weather, and it's main drawback of lower energy density isn't a big deal to trains.

I think the power requirements for the train might be the limiting factor tho. It's not quite the rocket equation but you can't just drain the whole battery pack on a 3% incline and get 15-30% back on the decline.

a 4000 HP train is ~ 2,000 kWatts. The average diesel-electric locomotive uses 3.5-4 kwh / mile of electricity (according to chatgpt). So to go 500 miles we're looking at 53,000lbs / 26.7 tons of _just_ battery (doubled up weight to account for non lithium). The locomotive itself can weigh 120-220 tons. A freight railcar can weigh about 100tons.

For a yard locomotive where they are just moving things around this could be super useful. For hauling freight around it's a potential? You're basically losing a freight car of cargo per 500 miles.

And I would really want this thing to be NOT made of lithium ion cuz if the train derailed it would be fairly destructive.[

25 tons in a 5,000ton ore train is a rounding error.

A typical locomotive carries approximately 5,000 gallons of diesel fuel, which at 7lbs a gallon is already 17 tons, not counting the weight of the tanks.

The diesel engines will be even heavier (and they're Diesel Electric, so they already have electric traction motors, and the related electrical equipment).

Train's don't haul just one car, they haul dozens or even hundreds.

You need something like 500 tons of batteries, even with superior efficiency numbers taken into account, to match the energy of 5,000 gallons of fuel. It is actually significant if people did the math correctly.

That certainly changes things somewhat, but I still think railroads would jump on it if it meant, say, 1/3rd less maintenance and half the fuel costs. The move to tier 4 emissions is/was a big deal. They’re starting to have to use DPFs and SCR.

Your quick calc actually seems to show how viable battery locomotives are, not how viable they aren't.

25t of batteries and you save all of the hassle and maintenance of combustion.

Please don't trust chatGPT for this. It is likely off by a factor of 10:

http://reasonrail.blogspot.com/2015/09/a-cost-to-benefit-ana...

It looks like 22-66 kWh/mile, depending on size of train.

The problem is that the cost of batteries pretty quickly undermine the cost savings of not fully electrifying the rail. If it is just a few miles, it makes no sense to have a fleet of battery trains for those short trips.

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