What we need for true perpetual energy is to just capture that guy Blanka from Street Fighter.

Surely that dude has to eat a lot in order to produce so much energy, no? Or is it just all stored somewhere in his body?

That's not how a railgun works, that's how a coilgun works. Railguns create a loop of electric current that flows into one "wire" (the rail), through the projectile into the other wire, and back down to the starting point again, this configuration creates a force that pushes the projectile down the rails