Quote Originally Posted by rsteinmetz70112 View Post
Interesting idea. Using multiple long thin tanks would tend to reduce the added height and possible allow a rack on top of the tanks. A quick google turned up some 2 GGE @ 3,000 psi
9" Diameter x 34.3" Long.

I don't know much about CNG. Is it liquid when in the tank? If so shifting weight could be an issue.
CNG is gasseous when in the tank, which actually makes it safer than LNG (which also requires cryo, as it has to be at -270 or so to be liquid), because it is lighter than air. The tanks on the roof would be fine from a legal perspective, most CNG applications on busses have them there. The tank you speak of would need 9 tanks to equal the 2 tanks that I was thinking of, so the mount would be much more complicated, and might actually end up weighing more. A 8-9 GGE tank that could go inside the vehicle would be about 14" diameter X 38 " long. Realistically, that would be big enough for about 1 weeks worth of driving, and would only cost about $10-12 per fill up. The cost savings is what I am really interested in, but engines also seem to run better on CNG, as there is less carbon fouling on the parts.