Banned from most residences in the US due to large, block-wiping natural gas explosions caused by home fueling stations the last time we tried CNG en masse in the 1970s. CNG refueling stations are now mostly restricted to commercial and fleet installs - no home install.
- - - Updated - - -
Ford did offer the CVPIs in CNG but they were more than disappointing - they lost a lot of power and when the fuel ran below about half a tank the car lost even more power; I drove several surplussed ones while looking for the CVPI I eventually bought (non-CNG). Honda offered a CNG Civic for municipal fleets that has had a tepid reception at best.
- - - Updated - - -
Yeah, we've been there before. The result (in the US anyway) is exploding houses due to the usual conduct of homeowners. That's why it's banned now.
Most of the "home" type alternate natural gas type vehicle fueling in the US these days is LPG/propane. You can legally have a propane fueling station at home if you have a residential propane tank, etc.