Apologies Mods - please move this thread if in wrong section. Traditional coal-fired steam engines are massively thermally inefficient and also suffer from limited availability and produce greenhouse gasses. Although unlikely and unnecessary, I was just wondering what a newly conceived steam locomotive might look like and what its capabilities would be given modern technology. EG engineering tolerances and turbine design knowledge is way better now, so would turbine be the way to go? Would steam / electric with an alternator be the way to go? What would one use as fuel? Would it have cabs at both ends a la diesels and electrics. Thoughts on how much would it cost to build one and get it certified for use on mainline?