Although the proposition seems a bit fantastic, there are other useful energies generated by trains. Now that US infrastructure is at a low ebb, there are many train crossings that are unprotected by danger warnings and the general stupidity of many drivers anxious to beat the train to the crossing results in a steady number of accidents when trains crash into trucks and automobiles. Surely the impacts of trains and cars generates much energy that could be conserved and turned into useful electricity given the number of ingenious contributors in this site who seem so fascinated with things like perpetual motion and other less practical machines.

I don't believe this would work. If something brushed against the train, the train would actually be slowed. The train would burn more fuel to maintain it's speed. The same goes with the wind that blows by the train. If something captured that wind, that too would slow the train. This is a little harder to explain. The train has to push it's way through the air which causes wind resistance. The wind against the side of the train is moving because the train pushed it. That wind that's now moving against the side of the train is causing less wind resistance against the train because it was already pushed. If you captured that force then it would drag the train against it's side. Think of it this way, for any action there's an opposite reaction. So, if wind is moving beside the train, the train made it move, if you take that away, then the train has to use equal amounts of energy to move it again. The train would burn more fuel.