Interesting conversation.
Waste Management has converted its fleet here in S. Florida to CNG. The engines are Cummins ISL based built by Cummins Westport.
The fueling station for retail sales is built, but I do not know if they have started selling to the public. I read an article while back that Waste Management will offer retail sales at all of their fleet locations in the future.
I have read where CNG is being rolled out at truckstops...so maybe the infrastructure is being built as we speak.
Natural gas is CH4, is lighter than air and has significantly different properties than propane.
The Waste Management "Clean Green Machines" are rolling on our streets down here every day.