December 4, 2017

Naval Group's Second Generation Fuel Cell (FC-2G) AIP Progressing

French magazine Mer et Marine (Sea and Marine in English) just over a year ago (October 7, 2016) published a very interesting article describing Naval Group's (was DCNS's) second-generation fuel cell (FC‑2G). That article is by Vincent Groizeleau at Mer et Marine is a paysite with perhaps a limited number of free views of the article's many photos, diagrams and much more text

The following is a summary of a small part of the article [with straight quotes where indicated]:

Naval Group’s Indret plant near Nantes, (in France) specialises in propulsion systems for the French Navy and for international customer navies. Since, around 2008, a team at Indret has worked secretly to develop a second-generation fuel cell AIP for submarine.
Naval Group's MESMA first generation AIP, now around 25 years old, 
[Pete comment...MESMA is essentially a modified version of France's more used nuclear submarine propulsion system. Instead of heat from nuclear fission MESMA uses heat generated by combustion of ethanol and oxygen. The problem is that unlike nuclear the MESMA system produces inadequate power and for too little time to accommodate nuclear grade coolant or heat shielding measures. While MESMA can generate more power than other AIP technologies this is at the expense of running detectably hotter and for a shorter time than competing AIP technologies. Just 3 foreign submarines (that is 3 Pakistani Agosta-90Bs) are fitted with MESMA.]

(Diagram from Naval Group (was DCNS) via Mer et Marine)
Naval Group is therefore developing a major improvement on MESMA, which is the second-generation fuel cell technology (with the acronym reversed in French being “FC‑2G”). In FC‑2G hydrogen is produced “[straight quote] from standard diesel fuel by chemical re-formation. In parallel with this effort, the group also developed a patented system to inject nitrogen into the oxygen supply line in the same proportion as in normal air resulting in a mixture that is far less reactive than pure oxygen. This ‘synthetic air’ is then injected into the fuel cells where it reacts with hydrogen to produce electricity.”

[Why FC-2G is better than competing approaches]
"[straight quote] Of the fuels considered by DCNS’s AIP engineers, fuel oil offered significant benefits over ethanol and methanol particularly in terms of safety: “methanol vapour is toxic in the event of a leak while ethanol is flammable at temperatures over just 13 to 14°C,” says Xavier Mesnet, a former submariner who today heads up the group’s Marketing and Development team. But this is not fuel oil’s only advantage. Fuel oil is easy to store and is the same as that used by conventional diesel-alternator sets. It is also readily available all over the world, and, “unlike hydrides, which require complex port and handling facilities, fuel oil is easy to store, purchase and transport”."


This 4 minute Youtube was published December 16, 2016. Presenters are Xavier Mesnet, Development and Commercial Support Director at Naval Group and Pauline Sibille, Naval Group Fuel Cell AIP Project Manager.

See current description of FC-2G on Naval Group's website as at November 4, 2017.


It would be interesting to know how much progress Naval Group has made since October 2016 in terms of packaging FC-2G for customer navies? 
-  Fitted or Retrofitted?
-  For India's Navy for the Kalvari-class and Project-75(I)?
-  any interest from the RAN for Australia's Future Submarine?

See Submarine Matters Air independent propulsion (AIP) Technologies and Selection, August 5, 2014 which compares the strengths and weaknesses of AIP technologies, including Stirling engine, PEM Fuel Cell and MESMA.



  1. Diesel reformation for fuel cells has been the subject of many researches in the past 20 years. There are substantial technical challenges from coking sulfur deposition, short lifecycle on catalysts operating at 1000C, design of direct injection nozzle, etc. and I am unsure if there are enough progresses made today to move it beyond the lab and/or prototype domains.

  2. Kalvari's first refit of 2023 could see the FC-2G AIP if the technology is matured enough by then and assuming DRDO/NPOL yet again fail to keep their deadline (looks likely both PAFC AIP and bio ethanol AIP are not going to be ready anytime soon)

    Pete, what do you think of a very small modular N-reactor AIP that can produce say 0.5 MW or so? should be doable given the most of the technology is available already?

  3. Hi KQN

    Yes I agree their has been more talk from countries and companies abould developing Reformer Diesel Fuel Cell than verifiable and marketable achievemwnts.

    As well as France I think Germany, Spain, Russia, Japan and India have all explored Reformer development with not much (publicly) achieved yet.



  4. Hi Ghalib Kabir

    Thanks for the assessment on AIP prospects for the Kalvari class.

    On what I think of a very small modular N-reactor AIP that can produce say 0.5 MW or so? I think for countries, like India and China, that have already leapt over the financial and political hurdles sufficient to produce full powered nuclear subs then half-way "small modular N-reactor AIP" may be usefull to put into the SSKs they want to build. So small modular N-reactor AIP fills a superior SSK niche.

    But for countries like Australia that has not leapt the part fixed cost nuclear establishment technical hurdles or persuaded its population that going nuclear propulsion is a good idea - then going to full nuclear first would tick more strategic boxes than small modular "half-way" N-reactor AIP.

    Canada is ahead of Australia in building things nuclear, but politically on the North American continent, the US can again say "no to Canadian SSNs". Australia, in part, chose SSN capable France to avoid the US nuclear propulsion veto.



  5. In my view, the cons of an SSK with a nuclear AIP are double the risks (since you double the systems), double expertise skill sets (dissimilar systems so you now need both nuclear engineers and diesel engineers on board), double the maintenance complexities not counting the special costs associated with future disposal and decommissioning. Since you are installing a nuclear reactor for AIP on board, you may as well make the jump to an SSN.

  6. Hey KQN, you are right about the costs (both money and manpower wise) and I agree that SSN or SSGNs offer much bigger weapon payloads, endurance etc..

    The thought process has its supporters in the Indian Navy too (i.e. a shift to a all N Sub force), however considering shallower water operating environments vis a vis pakistan and also the inherent advantages of n-AIP SSK such as smaller size, maneuverability, decent ability to operate quietly etc.., it might not be a bad idea to have a SSGN-SSK combine.

    the conclusion has been that a two tier sub-force, namely Nirbhay/Brahmos LACM/SLCM loaded SSGNs for the blue water navy part and SSKs for the littoral scenario has been agreed on. the PAFC AIP commercial manufacture trials (via Thermax India) and the Project 75(I) push are part of the outcome of such a thought process. the execution itself, I am afraid will be long drawn, tedious & likely capable of even enraging the Buddha into violence :(

    PS: The reactor and hull design for the Indian SSN is going to be challenging considering the stresses on the SSGN hull (as opposed to the Arihant boomer), not to mention the need for the reactor to be able to rapidly ramp up & ramp down in the case of combat scenarios.
    The Arihant reactor will most likely not suffice. I hope an SSN reactor is in the works.

  7. The Indian Navy should have had the foresight to incorporate FC2G AIP at the time of construction of the Kalvari Class, I hope they get it added on all six subs of this class in 2023 when they are due for major overhaul.
    In my opinion, the best option for AIP Scorpene Submarine (AM-2000), would be FC2G Fuel Cell + Li-Ion Batteries (at the time of construction replacing Submarine's Lead Acid Batteries with Lithium Ion Battries). The Scorpene AIP Submarine could operate for 6 days underwater on Li-Ion Batteries and on the 7th day FC2G Fuel Cell would recharge the batteries while powering the submarine for the duration the batteries are being charged. This would give the Submarine at least 8 weeks of submerged endurance! Li-Ion battery technology has progressed enough over the years that they can be added to submarines to replace the lead acid batteries! China & Japan are progressing with intigrainte Li-Ion battery into submarines, Naval Group should offer this if they want to beat the competition.
    Would like to know your thoughts about this. Thanks in advance.

  8. Thanks avi85 for your 5/10/18 11:24 PM comments on Second Generation Fuel Cell AIP "FC2G AIP" and/or Lithium-ion Batteries for Scorpene-Kalvari Class submarines.

    It is a question whether FC2G AIP and/or Lithium-ion Batteries should simulataneously be retrofitted to existing Kalvaries and fitted to late build Kalvaries.

    An "8 week" totally submerged performance would usually provide a whole discrete patrol for Indian subs versus Pakistani and Chinese subs and for other missions.

    I don't recall seeing much (or anything) from Naval Group indicating its Lithium-ion Battery research is mature enough to be offered as an option on production submarines.

    Might advanced AIP and li-ion be on land based test stands at Naval Group Cherbourg or

    Li-ion at Saft Battery France. LTO or NCA Li-ion batteries may be leads to follow-up




Pete/Pete2, will briefly reply to comments. Pete found he was commenting too much instead of writing articles.