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Comment by zactato | Hacker News Reader

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zactato·

My understanding was that rail was already pretty fuel efficient. Still, as the article said, things could be better.

How would this charge? Would you just swap out locomotives (battery cars?) periodically?

We have electric trains in city via overhead wires. I assume this becomes impractical at the freigh rail scales.

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In rail yards, charging is easily solvable (dc fast charging and having multiple engines for yard logistics). On long hauls, you could use a smaller generator such as a gas turbine that could accept a wide variety of fuels; think of this as a freight train version of the Chevy Volt. Your fuel is primarily for the energy cost of aerodynamic drag, as when the train slows, it’s regenerating into the batteries onboard.

Diesel locomotives have always been diesel generators mated to electric motors (too much torque for a transmission), so a battery pack is a natural progression for the powertrain. Zero emissions requires either green energy produced hydrogen or ammonia for combustion.

Most trains have been diesel/electric hybrids for a long time. I assume this is the same, the electric motors are just being powered by the batteries vs the generator, and the generator keeps the batteries charged up now. Presumably that allows them to do more interesting things with the motors which accounts for the efficiency improvements.

https://en.m.wikipedia.org/wiki/Diesel_locomotive#/media/Fil...

They're diesel with electric transmission, but not regenerative. Many locomotives have a visible box that contains just arrays of resistors used to burn off current generated during braking.

I always wondered if it would make sense to have a battery "tender" that could accept this current from a relatively stock diesel engine... so you replace, say, four straight diesels with three and one battery tender.

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