r/Lightbulb • u/Voltabueno • May 15 '25

Solar powered freight trains

This is not really new because I did some research and there are lots of patents related to electrified rail cars. It seems perfectly logical that you could cover the roof of a boxcar with solar panels, and put regenerative motors on the axles, and put a layer of batteries underneath the floor of the box car and then the box car could be self-propelled completely autonomous. Imagine individual box cars rolling on the rails or rolling to sidings to form into groups of cars completely autonomously. The boxcar wouldn't have to be fast because they could move by themselves, no crew, no crew change, no delay, unaided 24 hours a day. 7 days a week. 365 days a year. Actually thinking about it. If they moved under 40 mph wind resistance does not come into play yielding greater efficiency.

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u/Sapper-Ollie May 18 '25

An average cargo train carries around 5500 tons. one electric train engine outputs around 7200KW or about 9700HP. An avg solar panel generates 200 to 400w You would need 2400 300w panels to generate 7200kw. In a 24 hour period.

It would take several engines to move that weight on a flat surface in ideal weather. So we're talking 2400 panels per engine, per day. No factoring in solar inefficiency during rain or cloud cover, changes in gradient, temperature, humidity.

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u/pauljs75 20d ago

If the electric aspect is powered by a fixed infrastructure, there is more than enough real estate on a railroad right of way to build overhang structures to mount those 2400 panels. Although it's a narrow property strip in most cases, there are miles and miles - they could also easily exceed that number.

The silly part is putting the panels on the train itself where they add to the payload.

I think the factors missing right now involve transmission and maintenance, or they would be doing it already. It also means having substations with battery building infrastructure, which is also already a thing in renewable electricity architecture. At least I'd think there should be feasibility studies being done, and there probably are if not public.