The 259 will be, if the technology really works, the first co-gen engine, with the engine able to return power back through the supply source while running on third rail or catenary, to the power plant that supplies the electricity. It's also supposed to be able to run off straight batteries or use third rail or overhead wire, as well as the genset. I have a feeling this is all pipe dreams right now, since the locomotive was released as a standard genset, but we'll see.