Hmm, "and wherever they went they'd reduce CO2." That CO2 comes from the ocean, and at least some of it would be made into fuel. Once the fuel is burned, it returns the CO2 to the atmosphere. I assume that the ocean will absorb more CO2 to replace that removed, but it would take time. I think the process would be carbon neutral, with the possibility that it reduces CO2 in the ocean and increases it in the air. I'd think the same process can be used by a processing plant on land near the ocean, or on a rig at sea, and that all the world's fuel could be made this way. If the process is less expensive than drilling for oil and mining coal, it could be a sustainable source of fuel.
It also allows for the possibility of removing CO2 from the ocean and sequestering it (e.g., underground); thereby, reducing environmental CO2.