The primary purpose of an AIP system is to convert stored reactant energy into electrical energy for the submarine’s main battery and to do so independently of the surface atmosphere. It provides little benefit during transits but is invaluable when operating slowly within an operational area.
Further on the French FC, it appears as though two options are on the table; a PEM or Solid Oxide FC (‘SOFC’) type. If a SOFC is chosen, noting they offer good energy conversion efficiency, long life and operating cost advantages, other drawbacks need to be addressed. Most of these drawbacks relate to the high 600 to 1000°C operating temperature which brings hot exhaust issues and brittleness related shock resistance problems.