Then there are the mining trains that produce net energy: https://www.popularmechanics.com/science/energy/a39372219/self-charging-infinity-train/ https://www.p

Then there are the mining trains that produce net energy: https://www.popularmechanics.com/science/energy/a39372219/self-charging-infinity-train/ https://www.popularmechanics.com/science/energy/a39372219/se... If you're digging iron ore out of a mine and carting it on a one-way trip to the coast the train is always heavier on the way down than the way up. Store the energy from the downwards trip and use it to power the upwards trip, with some left over. Mind you this drives home the reality that mining is a non-renewable resource, as there is no such thing as a perpetual energy source or mine.