The US Navy just conducted a major Submarine planning exercise and I wonder if they recommended the purchase or construction of some AIP Subs. I hope they did. We should be building some to complement our fleet of Virginia class larger subs. A fleet of AIP Subs could keep China bottled up and cut off their supplies of coal, iron ore and oil.
According to the article, they are diesel-electric, so they need to receive diesel fuel every once and awhile. They may not be feasible for long deployments, but are perfect for coastal defense.