November 9, 2018

Could LIBs be combined with Stirling AIP? - Table.

Anonymous has kindly provided the comments (original words) and further translated by Pete below on November 8, 2018.

A full Lithium-ion Battery (LIB) system was adopted on the first Japanese Soryu Mark 2 submarine ("SS" sequence number 27SS – see red in Table below), which was launched on October 4, 2018. [Pete comment: A LIB system not only means 100s of tonnes of new type batteries but new or altered electrical wiring, connections, adjusted propulsion motor, adjusted consumer hotel load equipment (eg. computers), and many other weight conscious rearranegements = new buoyancy settings.]

LIBs replace the Stirling air independent propulsion (AIP) and lead-acid batteries (LABs) in previous Soryus (see Table below). The Japanese Ministry of Defense (MoD) and Navy adopted LIBs, because they perceived major problems in Japan's 13 years of using Stirling AIP.

More specifically in the older Soryu Mark 1 (AIP + LABs) submarines Stirling AIP’s drawbacks probably include/included:

i)  major weight, balance-buoyancy changes as 10s of tonnes of liquid oxygen (LOx) is consumed in the heavy LOx tanks. See “Combat Technology of Submarine” 2015 by H. Yamaichi. Ex-captain of JS Setoshio (SS-575) which was a Yushio class submarine). He was is also ex-Professor in the National Defense Academy of Japan. He said “Weight of goods (water, food, etc) is strictly controlled in submarine.”

ii)  low AIP energy output, which effects acceleration and speed, 

iii)  Stirling AIP can only operate at a diving depth down to 200m. See more below on this last diving depth point.

iv) [Pete comment: Time needed to warm up the AIP? AIP cannot be instantly accelerated or switched on to confront a crisis, like a Chinese torpedo.] 

The relative high costs of LIBs and Stirling AIP is an uncertain issue. It is not known why Japan did not decide to retain Stirling AIP and then add LIBs in a new submarine. 

[Pete comment - Note that Japan’s needs submarine stored energy (be it diesel, battery electricity or AIP chemicals) that is appropriate to Japan’s mission requirements. Requirements which may vary from short defensive missions to longer (4,000+ km) range missions in the western Pacific. AIP very well meets requirements in small enclosed seas but can have major overall drawbacks in open seas/oceans.]

Further to point iii) above - by recharging in gentle seas the LIBs Soryu Mark 2s can be operate for a far longer period than LABs-AIP Soryu Mark 1s (whose fully submerged operational period is controlled by the limited amount of LOx carried in Mark 1s).

According to Japan’s MoD, the replacement of Stirling AIP-LABs is because LIBs allow a longer time submerged. “In simple thinking, this statement seems to be false because energy from Stirling AIP is nearly 100 MWh larger than that from LIBs” (50 MWh). But, if a Stirling AIP-LABs Soryu needs to operate below a depth of 200m, it can no longer utilise AIP [due to AIP's no greater than 20 bars exhaust pressure limitations] and instead must rely on its LABs.

AIP’s diving depth limited down to 200m is a problem because Japanese submarines are operated in the Sea of Japan and West Pacific Ocean which are much deeper than 200m. In those standard situation a LIBs Soryu will yield a longer submerge period than AIP-LABs Soryu. [Pete Comment: Note, in using AIP Soryu Commanders, do not want to forego their sub's unusually deep max diving depth - maybe around 700m.] 

So Japan’s MoD has selected LIBs Soryus for full range-operation deeper diving efficiency.

AIP More Useful for Some Other Navies

In the case of the latest Chinese Yuan class 039A/041 submarines which use [covertly acquired, indigenous and/or bought] Stirling AIP and LABs, the situation seems to be a bit different form Japanese submarines. These Chinese submarines are intended to be mainly operated in the East China Sea [and use this inter-active sea depth map] which is mostly very shallow (almost three-fourths of the sea is less than 200m). There, China’s Stirling AIP-LABs system is still effective.

For the same reason, Sweden’s SAAB Gotlands and future A26s are/will be effective in the mostly shallow Baltic Sea. [Pete Comment: Also missions in the Baltic can be very short so Swedish sub’s can completely use their AIP with no LABs needed. Singapore which is using Stirling and soon German AIP on the new Type 218s may also enjoy only-need-AIP operations.]

Sweden and other countries may be interested in AIP + LIBs. Stirling AIP seems to compatible with LIBs. LIBs are used for operation under depths of 200m, and Stirling AIP improves endurance in shallow water. 

Also the recovered heat from the combustion gases of Stirling engines can be used for heating of LIBs to avoid thermal runaway at low temperatures. Cold sea (eg. North Sea and Baltic) users benefit most from the recovery-heat differential nature of AIP. Potential users include  the Netherlands' Walrus Replacement, German, Norwegian Type 212A/CD and, of course Swedish A26s.  

Though France’s Naval Group and German TKMS have already reported interest and some development of LIBs for submarine (probably most in collaboration with SAFT) Sweden’s SAAB, has not said much about adopting LIBs.


TABLE for SORYU & Oyashio Program as at November 9, 2018 

SS
No.
Diesel Type
Motor
Build No
Name
Pennant
No.
MoF approved amount ¥
Billions FY
LABs, LIBs, AIP
Laid Down
Laun
-ched
Commi
ssioned
Built
By
8105 Oyashio
SS-590/ TS3608
¥52.2B FY1993
LABs only
 Jan 1994
Oct 1996
Mar 1998
 KHI
6SS-15SS
Oyashios 
10 subs
2 Toshiba motors
SMC-7?
8106
-8115
various
SS-591-600
¥52.2B per sub
FY1994-FY2003
LABs only
 15SS Feb
2004
15SS
Nov
2006
15SS
Mar 2008
 MHI
&
KHI
16SS
Soryu Mk 1
12V25/25SB
SMC-8
8116
Sōryū
SS-501
¥60B FY2004
LABs + AIP
Mar 2005
Dec 2007
Mar
2009
MHI
17SS
8117
Unryū
SS-502
¥58.7B FY2005
LABs + AIP
Mar 2006
Oct 2008
Mar
2010
KHI
18SS
8118
Hakuryū
SS-503
¥56.2 FY2006
LABs + AIP
Feb 2007
Oct 2009
Mar
2011
MHI
19SS
8119
Kenryū
SS-504
¥53B FY2007
LABs + AIP
Mar 2008
Nov 2010
Mar
2012
KHI
20SS
8120
Zuiryū
SS-505
¥51B FY2008
LABs + AIP
Mar 2009
Oct 2011
Mar
2013
MHI
No 21SS
No 21SS built
22SS
8121
Kokuryū
SS-506
¥52.8B FY2010
LABs + AIP
Jan 2011
Oct 2013
Mar
2015
KHI
23SS
8122
Jinryu
SS-507
¥54.6B FY2011
LABs + AIP
Feb 2012
Oct 2014
7 Mar 2016
MHI
24SS
8123
Sekiryū
SS-508
¥54.7B FY2012
LABs + AIP
KHI
25SS
8124
SS-509
¥53.1B FY2013
LABs + AIP
22 Oct 2013
12 Oct   2016
MHI
26SS
end of SMC-8s
8125
Shoryū
SS-510
LABs + AIP
2014
6 Nov 2017
Mar 2019?
KHI
27SS First
Soryu Mark 2
12V25/25SB 
diesel
first SMC-8B
motor
8126
Oryū
SS-511
LIBs only
2015
4 Oct
2018
Mar
2020?
MHI
28SS  Second
Soryu Mark 2
12V25/25SB
SMC-8B
8127
SS-512
¥63.6B FY2016
LIBs only
2016?
Oct 2019?
Mar 2021?
KHI
29SS First Soryu Mark 3
SMC-9?
8128
?
¥76B FY2017
LIBs only?
?
?
2023?
MHI?
30SS Second Soryu Mk 3
12V25/31S
8029?
?
¥71.5B FY2018
LIBs only?
?
?
2024?
KHI?
Table from information exclusively provided to Submarine MattersLABs = lead-acid batteries, AIP = air independent propulsion, LIBs = Lithium-ion Batteries. ¥***B = Billion Yen. MHI = Mitsubishi Heavy Industries, KHI Kawasaki Shipbuilding Corporation of Kawasaki Heavy Industries. 
---

Thankyou Anonymous (with further translation and some [bracketed] comments by Pete).

5 comments:

Anonymous said...

Hi Pete

Full LIB system was adopted in Soryu Mark II instead of Stirling AIP-LIBsystem, presumably because of i) weight and balance change by consumption of LOx [1], ii) low output and iii) limitation of diving depth (200m) in Stirling AIP-LIB of Soryu Mark I. But, I do not think high price of LIBs affects on the selection of full-LIBs or Stirling AIP-LIBs, because Stirling AIP is also very expensive.

[1] Combat Technology of Submarine, 2015, H.Yamaichi. Ex-captain of JS Setoshio (SS-575, fierst Setoshio) and ex-professor of National Defense Academy of Japan. “Weight of goods (water, food, etc) is strictly controlled in submarine.”

According to MoD, exchange of Stirling AIP-LABs by LIBs provides longer submerge. In simple thinking, this statement seems to be faulse because energy from Stirling AIP is nearly 100MWh larger than that from LIBs (50Mw).

But, if Stirling AIP-LIBs Soryu is operated under depth of 200m, submarine operation is controlled by LABs. Japanese submarines are operated in the Sea of Japan and West Pacific Ocean which are much deeper than 200m, and in the situation, LIBs Soryu may shows longer submerge period than AIP-LABs Soryu. MoD selects LIBs Soryu for the full range operation of depth.

Bby repeating of charge in a calm sea, Soryu Mark II can be operated for longer period than Soryu Mark I whose operation period is controlled by amount of LOx.

In the case of latest Chinese 039 submarines for which Stirling AIP-LABs are adopted, the situation seems to be a bit different form Japanese submarines. These Chinese submaines are intended the operation in the East China Sea [2] which is largely shallow (almost three-fourths of the sea is less than 200 m, and its average depth is 350 m). Then, Stirling AIP-LABs system is still effective.

For the same reason, SAAB A26 is effective in shallow Baltic Sea. Stirling AIP seems to compatible LIBs. LIBs is used for operation under depth of 200m, and Stirling AIP improves endurance in shallw water and the recovered heat from the combustion gases of Stirling engine can be used for heating of LIBs to avoid thermal runaway at low temparature. Warlus, 212A/CD and A26 are used in cold sea such as the North Sea or the Baltic Sea.

Though Naval Group and TKMS have already reported LIBs for submarine as a result of collaboration with SAFT, the development by SAAB is yet reported.

[2] https://www.britannica.com/place/East-China-Sea

Regards

Anonymous said...

I don't think that it's any problem to install LIBs if the buyer wants it, I have seen a video where it is mention, cannot find it now and don't remember if it was in Swedish or English.

As the production method do allow easy functional adds or replacements as can been seen in Saab's annual submarine seminar 2017 like the vertical launching for missiles module, Polish requirement)

The presentation

/Kjell

Pete said...

Thanks /Kjell

I see no mention of LIBs unfortunately in what you've kindly provided, ie: "Saab's annual submarine seminar 2017" or "The presentation" which has slides of the seminar.

Regards

Pete

Anonymous said...

Sorry but the only video I found is in Swedish and in the Q&A section at the end, the second last question and the answer is that they are looking at LIBs, the actual question was the battery technology will be developted what will then happen with the Stirling technology? And he think the combination will work LIB Stirling will work perfect together Stirling taking the low speed and LIB the higher speed. So only a possible battery change. He also mention that they are looking at other AIP technologies the whole time but the Stirling will at least be around for the next 20 years.

And the very last question is about Australia :)

Something new about the A26 can maybe be presented at Saab Capital Market Day as it will take place in Karlskrona and it will be sent on the web 15 November 10.00, maybe hard for you to see due to the time difference, but it will be available on the web afterwards.

Link with details.

/Kjell

Pete said...

Thanks /Kjell [at 12/11/18 8:10 AM]

As the video you found https://youtu.be/x-uzLUEZiT8 is in Swedish your description is very useful, where you say:

"the second last question and the answer is that [SAAB] are looking at LIBs.

The actual question was [what] battery technology will be developed [and then] what will then happen with the Stirling technology?

[The speaker] thinks the combination [of Stirling taking the low speed and LIB the higher speed] will work work perfect together. "So only a possible battery change."

[The speaker] also mentioned that [SAAB is] looking at other AIP technologies the whole time but the Stirling will at least be around for the next 20 years." Thanks Anonymous.

Later today Submarine Matters will be publishing an article which links Japanese submarine LIBs with SAAB.

Regards

Pete