Here's some info on CNG. I just got back from a trip to Washington to haul back a fuselage with some good landing gear. I bought an old chev pickup with CNG (turned 300K on the trip). I had it figured out and I was supposed to make the trip for $125 up and $180 back. Didn't work out that way. In Utah it is no problem finding fuel for $1.25/gal but it is pretty scarce everywhere else. Some states don't have any public stations.
I topped off in Brigham City but when I got to Nampa I couldn't fill up. There were only two public stations on the way, one in Boise and one in Nampa. There are more stations but most are private for garbage trucks and municipal vehicles. I have the old 3000 PSI system and the station in Nampa only filled 3600 PSI systems so I had to finish the trip up on gasoline. You can use the 3000 pump to fill a 3600 system but you can't use a 3600 pump to fill the 3000 systems. They use a different fitting. I need to just make an adapter with a regulator so I can use the new pumps.
Seattle had stations and the fuel there was 2.05/gal. A guy in Seattle told me if I could use the 3600 pump, I could get 2 more gallons in. Don't think I'd try that but a couple people have told me the tanks are the same. Not sure if they are really gallons either but that is how the pumps read. I think it's a gallon equivalent.
I love using it but it gives you worse mileage and less performance. It was hard pulling a trailer unless it was flat. I'm sure newer trucks do a lot better on it and you can even get Diesel/CNG systems now. To fill it, it doesn't take long. Maybe 5 minutes. It just slows way down right there at the end. I have two big tanks under a tool box and the most I have ever got in was 14.5 gallons. Even big looking tanks don't hold much because the walls are probably 4 " thick and really heavy. It's an aluminum tank wrapped in fiberglass and they are pretty indestructible.
Watch some videos on You Tube of them crashing CNG cars, ( http://www.youtube.com/watch?NR=1&v=Z51NxNEBE4g
) they can take a Lot of abuse. Don't think you could use them in a plane because the tanks are so heavy but anything is possible. I doubt the systems for your house take all night to fill your car. It is basically a compressor but it has to pump 3000 or 3600 lbs. Probably takes longer than the commercial stations.
Some things I have learned with CNG:
1. Make sure you have a dual fuel system if you want to use the vehicle to travel in.
2. Get one that is the newer 3600 PSI system.
3. Check your tanks if your buying used because they are really expensive and they are only legal for 15 years on the older ones and 25 on the newer ones.
4. Don't run it all the way out by using it while decelerating or you will need to find an older pump to fill it with. Newer "Smart Pumps" will think there is a leak if there isn't enough pressure in your system and shut off.
5. More than half of the stations are private so call ahead if your planning on using them.
If you used a car to commute and could fill at home that would be great. This old truck costs about the same to drive as my Diesel Jetta. I love it!