Whats the retrofitting cost when going from CNG or indeed LNG towards BioMethane? Exactly – zero. You just put in the new fuel and the entire rolling stock, as well as all the refueling supply chain, is strictly the same. the source of the methane is going to be different and it will be more expensive as compared to the fossil gas but it you are OK with that, fair enough. You can do those things when you took the fundamental decision to go for the cleanest combustion fuel that exists. And as methane is not a chemical cocktail of different molecules but rather closer to a mono-molecular fuel there is no adaption necessary.
The Metropolitan Transportation Authority (MTA) issued a request for proposals to purchase ultra-low-carbon renewable natural gas to fuel some 800 New York City buses currently running on CNG.