I suggest trying your local natural gas companies. I was only able to find 1 place in the entire state of Minnesota that could refill tanks when I was using CNG. It was also a pain to deal with the company because they weren't a really service station. I basically had to call ahead and even then had to wait/nag until someone came to help me, but perhaps there are better options in your state. It's too bad because CNG is a great option for boats because of it's lighter than air properties, but I perfer propane because of the difficulty in finding a place to refuel.
Also, beware of CNG service stations for trucks and such, I found one of those, but it was self-serve and the hook-ups did not match, and it would be easy to overfill. Hope this helps, Gene
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