Question regarding AIP and O2 generation

[KawarthaCruiser]

I understand that the Victoria subs don’t operate under the northern ice pack for various reasons including:
• limited battery life without snorkeling/surfacing
• limited onboard oxygen without snorkeling/surfacing
• CO2 maybe a problem without snorkeling/surfacing but scrubbing techniques are available

Could one add sufficient fuel cells (hydrogen & oxygen used as fuel) to an AIP system on a type 214 submarine to support water electrolysis.  Producing oxygen for the crew and additional hydrogen as feed stock for the fuel cells?  Would the power requirements for electrolysis only be achievable on a nuclear-powered boat?

Apologies if this is a stupid question.  I’m barely allowed to change lights bulb in my house. 

 

[Colin Parkinson]

Not an expert, but apparently some AIP equipped subs have operated under ice. I expect in a wartime scenario they most certainly would if required. As to installing it, it is a complex task as some require liquid O2 which brings a host of other issues. A Sterling engine version might be done to extend battery life submerged but not to directly power the sub.

 

[Underway]

I understand that the Victoria subs don’t operate under the northern ice pack for various reasons including:
• limited battery life without snorkeling/surfacing
• limited onboard oxygen without snorkeling/surfacing
• CO2 maybe a problem without snorkeling/surfacing but scrubbing techniques are available

Could one add sufficient fuel cells (hydrogen & oxygen used as fuel) to an AIP system on a type 214 submarine to support water electrolysis.  Producing oxygen for the crew and additional hydrogen as feed stock for the fuel cells?  Would the power requirements for electrolysis only be achievable on a nuclear-powered boat?

Apologies if this is a stupid question.  I’m barely allowed to change lights bulb in my house. 

No, need for the crazy fonts and colours unless you are highlighting some other text.  Its just easier to read the base text for my poor eyes...  :nod:

No, it is not a stupid question!  Hopefully my answer isn't stupid sounding.

214 is a pretty small submarine (1800 ton submerged from wikkipedia).  Space is likely an issue.  AIP are also not very efficient for long range patrol which is what Canadian subs would need to do to make it even worth developing an under ice capability.

Electrolysis is something like 3% efficient in converting water to oxygen and hydrogen.  If you could do that efficiently we would all be driving hydrogen powered cars using the hydrogen from windmill powered electrolysis factories.

There is also a significant issue with fires in under ice operations.  Canadian submariners I assume don't relish the idea of fighting a fire without being able to surface, and unless you have the size and power (nuclear power to spare) you don't have the ability to either break through thick ice in an emergency or the power to make enough oxygen to deal with toxic air.  AIP just doesn't have the ability to do either of those things.

AIP is a useful tool but in the current form doesn't seem to have what it takes for safe extended under ice operations.

 

[KawarthaCruiser]

Colin & Underway, thanks for the feedback.  I didn’t realise that electrolysis was so inefficient.  Should have guessed at the poor performance, otherwise everyone would already be using it to extend dive times.  The thought of fire as a consideration never crossed my mind.  I’d just assumed that the fire on Chicoutimi was a onetime aberration.  Thanks again!

 

[suffolkowner]

The japanese are currently moving away from AIP in favor of more battery storage and higher energy-density batteries like Li-ion, I think the australians are looking at that option as well

 

[Underway]

The japanese are currently moving away from AIP in favor of more battery storage and higher energy-density batteries like Li-ion, I think the australians are looking at that option as well

Makes sense, batteries are the "original" AIP after all.  If you can get Li-I batteries to work they seem like an expensive but viable solution to improve your underwater run time.  Li-I batteries need a special circuit to charge that ensures they don't overcharge and explode and of course are very expensive compared to NiMH or Lead Acid.

 

[AlexanderM]

For those of us who would cringe at the idea of having Li-Ion batteries on a sub, is the Stirling system safer or better?

 

[Underway]

For those of us who would cringe at the idea of having Li-Ion batteries on a sub, is the Stirling system safer or better?

Stirling engines are really old technology.  Its how you create the heat which is where the risks are.  The Swedes, French, Russians and Chinese all create the heat differently for their various engines.  Using a Stirling system in and of itself is really very safe.  I have one that works on the heat from a hot coffee...

 

[Colin Parkinson]

Here is a good primer on AIP systems http://gentleseas.blogspot.ca/2014/08/air-independent-propulsion-aip.html

 

[JMCanada]

Very good summary  :nod:

Now my question is: how do nuke submarines use the energy to break up through the thick ice?
Is it just by pushing (propulsion) or might they use hot water jets?

Would it work to launch a torpedo to detonate some hundreds of meters away from the submarine to make the hole?

I have absolutely no clue on this.
Thanks in advance for your comments.

 

[Colin Parkinson]

I think they look for thinner spots and break through.

 

[Blackadder1916]

Now my question is: how do nuke submarines use the energy to break up through the thick ice?
Is it just by pushing (propulsion) or might they use hot water jets?

Would it work to launch a torpedo to detonate some hundreds of meters away from the submarine to make the hole?

I have absolutely no clue on this.
Thanks in advance for your comments.

Info.  Easy peasy, google squeezy

https://www.popularmechanics.com/military/navy-ships/a19681544/how-a-submarine-surfaces-through-ice/

 

[JMCanada]

Naval group has developed a diesel reforming system to feed a fuel cell. They call it Fuel cell 2nd generation. Reforming may well be the right path for an AIP- Arctic submarine, and in this field there are three systems under development:
- diesel reformation (french Naval group)
- methanol reformation (german TKMS + spanish Sener).
- bioethanol reformation (spanish Navantia + two companies working in parallel on two different solutions: Abengoa & Tecnicas Reunidas).

Navantia is expected to award the supply contract (for the S-80+ submarines under construction) to one of the above two next february (2020).

https://www.navalnews.com/naval-news/2019/07/naval-group-achieves-breakthrough-with-its-fc2g-aip-system/

https://www.edrmagazine.eu/naval-groups-fc2g-aip-is-ready-to-sail

 

[JMCanada]

More on AIP and reforming systems: the TKMS - Sener solution.

http://www.revistanoticias.sener/en/news/aip-system-for-submarines/50/

 

[Vimy Ridge]

Does anyone know if anyone has completed investigations into a "mini-reactor" sub that only provide enough power for life support systems, cruising speed, and trickle charging a backup battery meant for sprints?  I would think something like that could do under ice...

 

[Uzlu]

Does anyone know if anyone has completed investigations into a "mini-reactor" sub that only provide enough power for life support systems, cruising speed, and trickle charging a backup battery meant for sprints?  I would think something like that could do under ice...

An Autonomous Marine Power Source (AMPS) is being developed by a Canadian firm, Energy Conversion Systems (ECS), where work is currently at the development stage for a 100-kW plant. A family of designs to deliver anything from 100 to 1,700 kilowatts is planned for the long term.

Source: PDF page 13. 

But this was back in the early 1990s.  No support from the Canadian government—money—meant that, it would appear, no one has completed investigations into a SLOWPOKE-type submarine.

 

[Vimy Ridge]

Awesome - thanks!  I would not have been able to find that!  It's disappointing that Canada didn't explore that further.  I think the market for advanced submarines in the next years is going to be pretty significant...

 

[JMCanada]

Thank you Uzlu for the inputs.

Here it is a brief update on the state-of-art of LIB (lithium batteries) for SSKs.

https://www.aspistrategist.org.au/wp-content/uploads/2019/11/Woolner-Jones-media-background-lithium-battery-adoption-for-submarines-20Oct19-FINAL.pdf