A French friend drew the following to my attention. Here is part of Vincent
Groizeleau's Mer et Marine (all the maritime news), September
27, 2019, article (which I have translated from French and bolded some
bits) at https://www.meretmarine.com/fr/content/sous-marins-le-nouvel-aip-de-naval-group-tient-ses-promesses :
“Submarines: Naval Group's new AIP delivers on its promises”
Naval Group's development
of an Air Independent Propulsion (AIP) system for submarines based on a new
generation of fuel cells passed a crucial milestone this year. The ground
system of the Naval Group's, installed at its Indret site, close to Nantes [in
France], indeed worked for 18 days in conditions representative of a real
patrol. "It was a question of closely checking the functioning of the
system with a profile of operational use, as well as the autonomy of diving. For
18 days, the system, connected to batteries (to be representative of actual use
on a submarine) produced electricity from diesel fuel, operating at high
pressure, which means that it does not limit diving depth.
[The were simulations of] Transits, very
slow speeds, accelerations, fast surface rises, stops of the AIP followed by
restarting, management of a possible breakdown or damage ... As on a real
submarine, the system was confronted with situations to validate its
performance and reliability.
...Called
AIP FC-2G (Fuel Cell Second Generation - FC-2G), this system has required a
decade of research. Technologically, it includes two main
innovations. First, the hydrogen used for fuel cell operation is
manufactured directly on board, via a chemical reforming process from diesel
fuel used by diesel-generators. This process provides increased security
through the absence of hydrogen storage on board. The exhaust fumes are
discarded discreetly, since they dissolve instantly in the water. In
parallel, Naval Group has designed a patented system to produce air by
injecting nitrogen into the oxygen inlet of the cell, this oxygen is stored in
cryogenic form in a tank. Synthetic air reacts with hydrogen in the fuel
cell to produce electricity, which powers the submarine's batteries and the
electric propulsion motor. The battery is confined in a closed and
ventilated enclosure to control a possible leakage of hydrogen or oxygen.
1: the reformer is used to
produce hydrogen from diesel fuel
2: the component is used to increase the
hydrogen yield and eliminate the carbon monoxide produced
by the reformer
3: Purification membranes feed fuel cells with
ultra-pure hydrogen
4: Fuel cells produce electricity from
hydrogen and oxygen
5: the tank stores oxygen in liquid form
...Standalone operation or in tandem with batteries
Designed for a lifespan of 10,000 hours, the fuel cell
has a capacity of 250 kW. It feeds the electrical plant when the
submarine is in AIP mode, thus allowing the electric propulsion motor to run
and provides for the [submarine's hotel
load power needs]. The submarine can rely on this AIP system
alone at a speed of up to about 5 knots, knowing that to obtain
a range of three weeks in diving, the use profile varies between 2 and
4 knots. To do this, the power required for the AIP FC-2G is
between 130 and 180 kW. Beyond that, you have to tap into the
batteries, the passage from one energy source to another being done without
interruption.
Many advantages over other systems
Architecturally, the Naval Group AIP
FC-2G has a considerable advantage over existing AIP systems (that store
hydrogen in external tanks, posing weight problems (ie. 130 to 160 tons of
hydrides of which less than 2% is usable hydrogen) and other AIP systems
refueling problems). Fuel cells currently in service use, in addition,
pure oxygen, which generates high wear, with filters and membranes needing to
be replaced very regularly. AIP FC-2G is more efficient, according to Naval Group, as AIP FC-2G offers
(according to its designers) duration of use between each major maintenance
approximately five times higher than that of its foreign
competitors. "Our system really fits into the operational scheme of a
submarine. It only requires a short interruption of three weeks each year
- the only equipment to be changed during this maintenance period being the
catalysts. In the meantime, there is nothing to do! Says Marc
Quémeneur [AIP product manager at
Naval Group].
Finally, the choice of hydrogen
production from diesel fuel facilitates refueling and storage (single fuel on
the submarine) while improving safety compared to systems using, for example,
methanol, which are more flammable and introduce toxic products in case of
leakage.
The device fully integrated in a standalone
module
Like MESMA, (the first AIP developed by
the French group and which equips Pakistan’s Agosta 90Bs) the entire AIP FC-2G
system is grouped in a single module, autonomous from the rest of the
submarine. The system is housed in a hull section about 8 meters
long integrated into the submarine from the beginning or added
after overhaul with a minimum of modifications to the submarine. AIP
FC-2G is adaptable to
submarines with a diameter of at least 6 meters, such as Scorpene or
the conventional propulsion version of the Barracuda. AIP FC-2G is
obviously designed not to impact overall performance, starting with diving
depth and acoustic discretion.
...AIP FC-2G is therefore "ready to be
marketed" and already proposed by Naval Group to a number of navies.
...While AIP FC-2G has been tested with traditional
lead-acid batteries, Naval Group is also working on integration with
submarines using lithium-ion battery technology, which will
expand operational performance. ENDS
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See Vincent
Groizeleau's full Mer
et Marine report, with more illustrations, here https://www.meretmarine.com/fr/content/sous-marins-le-nouvel-aip-de-naval-group-tient-ses-promesses
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Pete Comment
Naval Group may well have timed this
article with a view to India's Project 75I competition for 6 submarines with AIP. Also the
Dutch Walrus submarine replacement competition may require AIP. Australia,
building 12 conventional propulsion versions of the Barracuda
(known as the
Attack class) may also decide on AIP for the first or later batches.
Current users
of Naval Group Scorpenes (Chile, Malaysia, India and Brazil) might perhaps also
decide to retrofit their Scorpenes with AIP FC-2G.
7 comments:
With recent development in renewable energy, I am afraid this French AIP will probably be out of date within the next decade.
Here are two new technologies which I believe are very simple to incorporate into existing systems which can become the next AIP system that can come close to nuclear AIPs.
First is an electric CO2 scrubber that can extract CO2 directly from stream of air utilizing electricity.
https://techxplore.com/news/2019-10-carbon-dioxide-air.html?utm_source=nwletter&utm_medium=email&utm_campaign=weekly-nwletter
Next is an artificial leaf that generates Syngas by combining CO2 and water through a catalysis and light with Oxygen as a by-product.
https://techxplore.com/news/2019-10-artificial-leaf-successfully-gas.html?utm_source=nwletter&utm_medium=email&utm_campaign=weekly-nwletter
Syngas is a mixture of CO and H2 which you can burn turning back to CO2 and H2O.
You can use sea water and the CO2 can be obtained by releasing the CO2 captured by the electric scrubber mentioned above and the light can be an artificial source utilizing LED powered by the battery discharging power to release the CO2.
I doubt it will be as powerful as nuclear but I believe it can be a perpetual cycle as long as you clean out the salt within the syngas generation chamber.
I remember reading a DTOE.mil report dated 2012 or 13 that hinted how the BYG-1 was a power hog when used at max capability... got me thinking on the ISUS 100 and DCNS S-Cube system. The ISUS 100 has a vast power hungry spec for a SSK in hinter-killer mode.
https://www.atlas-elektronik.com/fileadmin/user_upload/01_Images/Solutions/Datenblaetter_zum_Download/ISUS100.pdf
this ISUS 100 alone if operated at full power will need more power than an AIP can provide (hotel power centric thinking might not suffice)
http://www.dept.aoe.vt.edu/~brown/VTShipDesign/2007SSLOIFinalReport.pdf
if the S-Cube or ISUS 100 or the AN/BYG-1 is used at full power, then I think 2x500 kW AIP would be minimum needed as you can in table 46, the combat system alone consumes 220 kW approx. even the newer Siemens 4x120 kW PEMFC on the 216 or the 250 kW FC2G won't cut it...as total functional needs imply a PAFC AIP of 2x500 kW is a more likely (the high heat needs to be captured to say warm water or do other stuff as else PAFC is dangerous)
then we have hotel load increase and related noise issues when propulsion at 4-5 kt is considered with combat systems & other stuff at near full power..
PS: what is the point of having a good combat system if power supply can crimp performance ability? at lower power an Indian Scorpene with the S-Cube might struggle to find a 'relatively' noisier MESMA mounted PN Agosta 90B as the S-Cube sharing a 250 kW AIP system (assuming battery conservation to protect indiscretion ratio) will have very low capability possibly.
Hi Tri-ring
Many people and especially startup companies market new technologies as the nifty future best technology for submarine AIP and new technology batteries.
The main expense it taking the 10 odd years and half a Billion dollars to integrate the technology in a submarine under operational conditions.
You're right that no foreseen AIP - maybe propelling a submarine at 6 knots for 3 weeks will never approach the capabilities of nuclear submarines - with SSNs traveling at 34 knots for 4 months (main limiter being food for the crew).
Regards
Pete
Hi GhalibKabir [at October 31, 2019 at 10:12 AM]
Thankyou for the links and comments on the inadequacies of AIP to meet the full power needs of Combat Systems (major components of Hotel Loads]. This is not even counting a SSKs simultaneous propulsion needs.
Perhaps AIP (as used by Sweden, Germany, Japan, South Korea, Singapore and others) is principally a Sit on the Seabed and Monitor power source.
Monitoring (say in the approaches to an "enemy" port or the Straits of Hormuz or Malacca) would be at a low combat system (passive sonar) setting, to pick up sounds of submarines, surface ships and non-state actors (pirates, drug smugglers, terrorists, etc).
AIP may also be an emergency power source when a submarine wants to escape quickly or is forced to stay submerged (in peacetime) with batteries depleting as anti-submarine ships and aircraft loiter above.
Regards
Pete
Dear Tri-ring,
the techniques you introduced are not that useful to a submarine.
There is no need to remove carbon dioxide from a submarine e.g. AIP with methanol based fuel cells. You get pure carbon dioxide you have to dump overboard.
The "artificial leaf" is interesting but a submarine won't completely surface to produce energy by light. A Type 212A submarine uses one 1000 kW Generator to reload the batteries. With a "leaf" converting 100 % sunlight into energy you would require about a leaf size of about 1.000 m² ~30 m x 30 m or 10 m x 100 m. I also don't want Syngas on a submarine. Carbon monoxide is very toxic. There are no fuel cells for CO and H2. Therefor you would have to burn the gas in an engine. Sterling engine maybe.
Regards,
MHalblaub
Hi MHalblaub
Thanks for your comment.
AIP certainly looks inadequate for (say 6 hours of) high speed, high hotel load (especially combat system) functioning of a submarine.
The Lox tank and other AIP apparatus would quickly become a dead weight burden, once the AIP chemicals (ie Hydrogen and Oxygen (via Lox)) have been used up.
Am I right in saying even Naval Group's Diesel Fuel for Hydrogen 2nd Generation Fuel Cell AIP is limited by the Oxygen it can carry in the heavy Lox tank?
Regards
Pete
MHalblaub
I am guessing you haven't read the article attached.
First off you need to remove CO2 from the sub or the crew will suffocate. That is why subs are equipped with chemical CO2 scrubbers but they need to carry additional scrubber cartridges to replace the old ones in a diesel sub since there is no way to generate Oxygen unlike Nuclear powered subs.
The Electronic scrubbers within the article posted can be used so to reduce the storage of chemical scrubber cartridges to bare minimum for emergency purposes.
The stored CO2 within the electric scrubbers again written within the article os utilized by the artificial leaf which generates Syngas by combining water(H2O) and Carbon Dioxide(CO2) through a a catalysis and light.
The light does not need to be sun light therefore it can be substituted with Blue light LED powered by the battery discharge to extract the CO2 stored within the electric scrubber.
The Syngas can be used as fuel to power a generator. All being done while remaining underwater thus making it a very efficient AIP system.
With this system you do not need LO2 since the O2 is generated as by-product in generating Syngas through the H2O+CO2 chemical reaction creating CO+H2+O2
No this is not a perpetual engine since there will be energy loss at each conversion point so it will not run forever but it will prolong the run without extra luggage to carry around which is a major plus for a sub.
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