April 24, 2015

Soryus on Lithium-ion Batteries an Evolution Not Revolution

The following is mainly drawn from discussions between "S" and Pete on the Comments thread for Air Independent Propulsion (AIP) Issues of April 23, 2015. A big thankyou to S for doing the estimates and providing other comments. 


Reuters reported November 19, 2014 that Australia wants its future submarines to use Lithium-ion batteries (LIBs) and no AIP. 

S advises that originally Stirling AIP was unpopular in the Japanese Navy, because of its low power (2.5knots) and complicated operation. For Japan AIP was only a temporary measure on the Soryu until Lithium-ion batteries (LIBs) became a more mature technology.

Looking at the Table at the bottom of this article you will see the first tranch (Mark 1) of what may eventually be up to 12 Soryu submarines are known as “16SSin red. 16 is the last two digits of the Soryu’s first of class’s “Building no. 8116” and “SS” means conventional submarine. The “Soryu” 16SS was commissioned in 2009. 16SS is diesel-electric with lead-acid batteries and Stirling AIP.

Published figures for 16SS range/speed (see sidebar of Wiki) would most likely be for semi-submerged snorkel/snorting mode. 16SS fully submerged (no snorkel use) figures are classified but S’s estimate for submerged speed and endurance is 6 knots for 3 days.

The aim of S's input is to give an estimate for the fully submerged range/speed of the second tranch Mark 2 Soryu’s further down the Table, known as 28SS in red. The first of class 28SS may be commissioned in 2022. It will not have AIP but instead will have new Lithium-ion batteries (LIBs).

As yardsticks for comparision are:

- the Collins submarine, has lead-acid batteries totalling 400 tonnes. Its submerged speed x duration = approximate range is 4 knots for 5 days = 480 nautical miles.

- while German submarine U-32's (a HDW 212A) 2013 test using an initial diesel engine charge  with lead-acid batteries then fuel-cell AIP charging the batteries achieving 6 knots for 20 days = 2,800 nautical miles.   

S estimates 28SS (using Lithium-ion Batteries) submerged speed x duration = approximate range will be 4 knots for 30 days = 2,900 nautical miles. 

S's calculations are on the Comments thread here.

PETE'S COMMENT

One must remember that the above are estimates based on several assumptions. It indicates that in terms of range LIB will be similar to AIP using lead-acid batteries. However using AIP and LIBs a sub would have a much longer range submerged performance. The safety-danger issue for AIP from fire is higly significant - so it and other LIB - AIP comparitive issues will be discussed in a future article.  Ultimately issues and comparisons will only be possible once Mark 2 Soryus (28SS) and HDW subs with AIP and LIBs come into service after 2022 or so.

Australia would want a transit speed (Fleet Base West, Rockingham, Western Australia to around Darwin and alternatively Rockingham to Sydney) of perhaps 12 knots. After that an Australian sub may rely on much more fully submerged LIB use in order to stay out of view of Chinese satellites (keeping away from Chinese undersea sensor arrays is another problem).

Variables that are difficult to predict are whether the next tranche Mark 2 Soryus (28SS) is larger or smaller than 16SS or whether Japan may build an Australia-only version.

LIBs and/or AIP still will not compare to the performance of nuclear propulsion. 

Two useful two web documents are:

-  http://en.wikipedia.org/wiki/Drag_(physics) , “Drag at high velocity”“Power” (in fluid dynamics 6 knot/h is high velocity).

-  https://samueldavey.files.wordpress.com/2013/04/fluid-dynamics-submarine-report.pdf an Australian Maritime College paper of 30 pages. This is especially interesting. It draws on Australian Defence Science and Technology Organisation (DSTO) findings. It explains why submarines are shaped as they are and what modifications can make them move more efficiently.

For further information on LIB issues and other Soryu issues see many more articles on Submarine Matters, including:


MHI and KHI not at Australia's Future Submarine Summit, Adelaide, March 24-26, 2015 of March 24, 2015, and

Air Independent Propulsion (AIP) Issues of April 23, 2015.

------------------------------------------------------------------------------------------

Soryu 16SS can be called "Soryu Mark 1s" with Stirling AIP. Future Soryu 28SS can be called "Soryu Mark 2s" with no Stirling AIP but they will have Lithium-ion batteries (LIBs). 


SS
No.
Building
No.
Pennant
No.
Name/Namesake
LAB or LIB & AIP *
Laid Down
Laun
-ched
Commi-ssioned
Built
By
16SS
8116
SS-501
Sōryū (そうりゅう) / Blue Dragon
LAB + AIP
March 2005
Dec 2007
March
2009
MHI
17SS
8117
SS-502
Unryū (うんりゅう) / Cloud Dragon
LAB + AIP
March 2006
Oct 2008
March
2010
KSC
18SS
8118
SS-503
Hakuryū (はくりゅう) / White Dragon
LAB + AIP
Feb 2007
Oct 2009
March
2011
MHI
19SS
8119
SS-504
Kenryū (けんりゅう) / Sword Dragon
LAB + AIP
March 2008
Nov 2010
March
2012
KSC
20SS
8120
SS-505
Zuiryu (けんりゅう) / Sword Dragon
LAB + AIP
March 2009
Oct 2011
March
2013
MHI
22SS
8122
SS-506
Kokuryū (こくりゅう) / Black Dragon
LAB + AIP
January 2011
Oct 2013
March
2014
KSC
23SS
8123
SS-507
Jinryū (じんりゅう)/ Benevolent Dragon
LAB + AIP
Feb 2012
Nov 2014
March
2016?
MHI
24SS
8124
SS-508
?
LAB + AIP
2013
2015?
2017
KSC
25SS
8125
SS-509
?
LAB + AIP
2014
2016?
2018
MHI
26SS
8126
SS-510
?
LAB + AIP
2015
2017?
2019
KSC
27SS
8127
SS-511
Soryu Mark 2 
LIB only
2016?
2018?
2020?
MHI
28SS
8128
SS-512
?
LIB only
2017?
2019?
2021?
KSC
29SS
8129
SS-513
LIB only
2018?
2020?
2022?
MHI






























 1st Australian class?





* LAB means Lead Acid Battery, LIB is Lithium-ion Battery, AIP is Air Independent Propulsion

29SS will be a new submarine class (no longer called Soryu). 

New features for the Next-Generation Submarine - 29SS - may include:
-  A more effective and powerful snorkel generation system for recharging the LIBs.
-  A next generation sonar system
-  Introduction of the Next-Generation heavyweight torpedo known as G-RX6.
-  An improved platform to reduce vibrations. This platform will be more impact resistant.

Again thankyou S for doing most of the work :)

Regards


Pete    

12 comments:

Anonymous said...

Hey Pete. Thanks for this article.

"The knot is a unit of speed equal to one nautical mile (1.852 km) per hour, approximately 1.151 mph." (wikipedia)

So knot/hour would be an acceleration :-)

Have a lovely weekend.

Peter Coates said...

Thanks Anonymous

I shall adjust the wording accordingly :)

Have a good weekend to.

Regards

Pete

Anonymous said...

Hi Pete

I am awfully sorry that I found some faults on data. Right information or data is as follows.

JMSDF had developed proto type LIBs which were equivalent (nearly same size and weight) to lead acid batteries (LABs) in FY2002-2005. The LIBs showed higher enegy density (LIBs/LABs ratio of energy per unit volume or weight >=2), longer life duration (LIBs/LABs ratio of repeatable number of charge-discharge cycle>=1.5), higher charge efficiency and better safety than the LABs.

I think that submerged speed and range for 28SS will be lower and shorter and that submerge duration does not change (=30days).

Regards
S

Peter Coates said...

Hi S

No worries mate.

So what is the revised estimate for speed/range?

Regards

Pete

Anonymous said...

Dear Pete,

I can see some questions related to the specific energy (Joule/kg)of even the best lithium batteries. Today the best value is less than 1 MJ/kg. That is for the pure battery without installations. Specific energy for diesel is over 40 MJ/kg (with loses due to energy conversions) and 20 MJ/kg for Ethanol (the next AIP fuel). These values are also without installations to produce the energy e.g. diesel engine + generator or fuel cells + oxygen.

For sure for small amounts of energy the battery has the best total specific energy density = energy per weight of total installations. For large amounts of energy a diesel generator will provide better results.

The diesel generators on submarines are far to big to provide a steady stream of energy. They are so big to provide a peak power to recharge the batteries as fast as possible.

A submarine needs batteries to operate submerged with high speed / acceleration.

A fuel cell like a diesel generator provide no energy without fuel. They are just dead weight. By adding more and more fuel the total specific energy gets better. At one point a fuel cell with all the installations and tanks has a better specific energy than a battery.

A rough estimation about energy output. Collins-class can travel about 500 nm with 400 t of lead acid batteries. With LIBs twice as good the battery weight would just be 200 t. To travel 5,000 nm Collins-class would need about 2,000 t of LIBs. Therefore LIBs have to be far better to provide 5,000 nm at 7 kn even for a 4,200 t submarine. Maybe the next Soryu-class will be a battery only submarine like the Peral submarine.

On the other side the small Type 212 (displacement 1,800 t submerged) can travel about 3,000 nm at ~ 5 kn (U 32, exercise Westlant deployment 2013).


Regards,
MHalblaub

Anonymous said...

Hi Pete

I assumed that submerged speed of 16SS and 28SS by batteries is same as that of Collines (4knot/h). Then submerged range of 28SS will be 4knot/h*24h*30day= ca.2900nm.

By the way, I find the interesting information [3] on AIP sub development in Australia. And I validated AIP submaerge speed of 16SS based on this information.

1) Equation
Fd = 1/2*M*V*V*Cd*A (1)
Propultion power = Fd*V (2)
Fd = drag force
M = mass density of the fluid = constant
Cd = constant
V= speed of submarine: 4knot/h (Type2400 submarine, AIP requirement), V(16SS-AIP)
A= reference area = diameter*diameter/(4*3.14): diameter = (beam+draught)/2, 7.4m (Type2400), 8.8m (Soryu)

2) AIP Speed of 16SS
As AIP power is low, we must consider effect of hotel load (100-200kW), which is electricity generated and used aboard a ship for purposes other than propulsion[5]
Total power (16SS-AIP) = 75kW*4 = 300kW
Hotel load (16SS-AIP) = 200kW (as Soryu is big, hotel load becomes maximum)
Propulsion power (16SS-AIP) = total power - hotel load=100kW
Propulsion power (Type2400-AIP) = 50kW [3]
From eqs (1), (2) and data including propulsion power, I obtained V (16SS-AIP) = 2.8 knot/h. The result consists with reported value (2-2.5knot) very well.

3) Reference
[1] http://en.wikipedia.org/wiki/S%C5%8Dry%C5%AB-class_submarine
[2] http://en.wikipedia.org/wiki/Upholder/Victoria-class_submarine
[3]http://www.google.com.au/url?sa=t&rct=j&q=&esrc=s&source=web&cd=2&ved=0CCQQFjAB&url=http%3A%2F%2Fwww.dtic.mil%2Fcgi-bin%2FGetTRDoc%3FAD%3DADA304112&ei=drtAVb37FeHTmgWGpID4CA&usg=AFQjCNFkHrqU6FJcUZayl_6cNLoASN38ng&bvm=bv.91665533,d.dGY “Fuel Cell Air Independent Submarines” page 2.
[4] http://en.wikipedia.org/wiki/Drag_(physics)
[5]http://en.wikipedia.org/wiki/Hotel_Electric_Power

Regards
S

Peter Coates said...

Hi MHalblaub

S's (April 30, at 12:36 AM) revision downward of 28SS's performance on LIB (to 4 knots*24h*30day = ca.2900 nautical miles) seems more in line with your calculations. I shall amend the text accordingly.

It is indeed approprite to compare Soryu 28SS's 4 knots*24h*30day = ca.2900 nautical miles with U-32's (a HDW 212A) performance at Exercise WESTLANT.

U-32 used fuel-cell AIP in March/April 2013 achieving figures of 6 knots in 20 days = 2,800 nautical miles . Apparently U-32 still had AIP fuel to spare after that. Source is http://www.public.navy.mil/subfor/underseawarfaremagazine/Issues/Archives/issue_51/WESTLANT.html .

One difference between them is safety of fuel-cell AIP vs use of LIB. This will be increasingly complex when HDW will offer AIP and LIB in the one submarine. Also LIB in submarine isn't fully or publically tested.

I'll do a new article comparing LIB with AIP over the next week or so.

Regards

Pete

Peter Coates said...

Hi S (April 30, 12:36 AM)

Thanks for revising 28SS's performance on LIB (to 4 knots*24h*30day = ca.2900 nautical miles) showing how you recalculated it.

As LIBs on Soryu haven't been publically tested all we can rely on is estimates. But the more estimates are discussed the more accurate they may probably get.

Note that figures for U-32's (a HDW 212A) performance at Exercise WESTLANT in 2013 were even better at 6 knots in 20 days = 2,800 nautical miles. http://www.public.navy.mil/subfor/underseawarfaremagazine/Issues/Archives/issue_51/WESTLANT.html .

A big difference though was that U-32's lead-acid batteries already had an initial charge using the diesel engines BEFORE AIP was used. Also there may be significant safety differences between the AIP and LIBs.

I'll do a new article comparing LIBs with AIP over the next week or so. This needs to take into account limitations of LIBs not being publically tested on Soryus or HDW 212s.

It might ultimately be up to the Soryu builders and HDW to publish comparisons.

Regards

Pete

Anonymous said...

[Moved to correct comment thread]

Hi Pete and MHalblaub

Weight of a module consisted of 10 lead acid batteries is 800kg and 16SS equips about 50 modules (40t, excluding controller). LIBs module has nearly same dimension and is 4% lighter.

Regards
S

Anonymous said...

Guys - your estimates of endurance of a Li-ion equipped boat are widely optimistic. At low rate discharge you will get about a 30% increase on a Lead acid of the same volume. The tactical advantage is in the charging rate resulting in a lower indiscretion rate ie you can charger at a higher rate to a higher level of charge. The other advantage is that for the same battery volume you achieve a 50% weight saving. The down side is that the Li-ion chemistry is flammable and subject to unexplained failure modes resulting in fire (ie the Boeing 787 experience).

Anonymous said...

Hi Pete and Anonymous

As I did not have information of Soryu structure including batteries configuration, I am sorry that I could not simulate well. But I believe LIBs submarines show much better performance than LABs (lead acid batteries) submarines, because we can expect improvement in LIBs performance (data of LIBs was old one of ten years) and performance of LABs is much inferior to that of LIBs as follows.

Depth of discharge (DOD, nominal ampere-hour capacity) is important performance index of rechargeable batteries including LIBs and LABs, and if the DOD is lower on each charge/discharge cycle, rechargeable battery system will tolerate more charge/discharge cycles [Wikipedia]. I heard that limits of DOD for maintaining stable and repeatable perfomance is 36% and 90% for LABs and LIBs, respectively.

In the case of Collins subs, continuous submerged period at 4knot/h is nearly one and half day (4day x 0.36 = 1.44day) to subsequently maintain stable and repeatable submerging, I think that 4 days coninuous submerging will be conducted only in emergency. In the case of virtual Collins which uses LIBs, continuous submerged period is more than three days (4day x 0.9 =3.6day).

Regards
S

Peter Coates said...

Hi Anonymous (May 19 at 1:54 PM)

Noting S's May 20 response.

No doubt that LIB performance and safety is one of the most complex issues facing the future submarine selectors.

1. Very likely that TKMS and DCNS are also being asked to present LIBs. Making the selection partially "which country can provide the most efficient LIBs?"

2. How to define LIB or LAB efficiency and safety against all other considerations in a submarine build?

2. Does the much higher mass (which may integrate fire retardant) of submarine LIBs make them safer than aircraft LIBs? What is the current usage and safety of aircraft LIBs?

3. Would it be necessary to include some type of AIP and/or LABs as backups in case of LIB fire?

4. Given technical innovations how safe and efficient will LIBs be in 2025 when Australian future subs will begin to be built?

5. By 2025 will increased Chinese ASW sensor performance and increases in seafloor nodes and line arrays make any diesel charging too dangerous anywhere near China?

Regards

Pete