Was at a model railroad meet at a live steamers group earlier this year. Great place, good food, lots of rides. Operating locomotives included a small coal burner (the owner said that it wasn't used often because it's hard to get the right coal for it any more); a propane burner (most of their locomotives in regular use - they give rides to the public on many weekends - run on propane, mainly because it's easier to use and refuel); and a big SP Mountain model running (prototypically) on oil (diesel fuel, like most modern steamers at 12"=1'). Mixed with bbq, made for an interesting collection of odors. But no woodburners (kind of hard to do in small scales, and there had been a nearby small brush fire a few weeks earlier and people would get a little concerned about THAT smell again). One G-scale live steamer ran on alcohol, which is usually a biofuel.