I think the fact that they put a price per gallon on it is clue enough the energy isn't free, and that they would be using an external source. But yeah, the fact that everyone is touting it as free fuel isn't helping...
This would be a fantastic technology to have on a carrier. Frees up a lot of storage space for other stuff. Also, not having to carry around as much fuel should make it safer, too.
But $3 sounds incredibly optimistic. If that factors in start-up cost, also, then that's something that could go straight to commercial sale.