One of the reasons for moving to methane is that it burns clean, dramatically reducing soot, and thus smoke. AFAIK, this is primarily so you can reuse the engi

One of the reasons for moving to methane is that it burns clean, dramatically reducing soot, and thus smoke. AFAIK, this is primarily so you can reuse the engine without major cleaning/refurbishment, but it should also significantly reduce pollution. Noise, on the other hand... ¯\_(ツ)_/¯