Lithium and Submarines

 "The final hour when we cease to exist does not itself bring death; it merely of itself completes the death-process.  We reach death at that moment, but we have been a long time on the way." - Lucius Annaeus Seneca

I was catching up on the news this morning, and this article in the Asia Times caught my eye:  China intends to replace old-school lead-acid battery cells on their diesel-electric submarines with lithium ion cells. 

 

The article goes into a little depth about the hazards of lithium batteries, and mentions safety precautions that the Chinese military believes will help to mitigate the hazards.  They also link to another article that specifically discusses lithium-based batteries and their hazards. 

Diesel-Electric submarines have a major strength, and that is how incredibly quiet they are.  A modern diesel-electric submarine is very difficult to detect, because - unlike a nuclear sub - there is almost no propulsion machinery noise.  A diesel-electric submarine running off the battery will have only the whine of an electric motor turning the propulsion shaft, and a few auxiliary systems, such as HVAC.

A nuclear submarine will need to operate reactor cooling pumps, condensate and feedwater pumps, several steam turbines, and a massive reduction gear to reduce propulsion turbine speed down to the appropriate speed for the main propulsion screw(s).  There will be associated flow noise with these systems, particularly steam flow noise across turbine inlet throttle valves.  And while all of this equipment is sound-isolated from the hull, the nuclear platform will always be noisier than an equivalent electric sub.

Diesel-Electric boats also have a glaring weakness, and that has always been their submerged speed and endurance - which is limited by battery capacity.  Whenever the charge on the main storage batteries is exhausted, the ship must return to periscope depth, extend the snorkel mast, and fire up the diesel generators to re-charge the batteries for several hours.  This causes a couple of difficulties:

• The ship may well have to come off station from conducting surveillance in order to charge the batteries.
• While charging the batteries, the submarine is much more vulnerable to detection due to either sonar (diesel noise) or radar (the snorkel mast is large)
• While lingering for long periods of time near the surface to charge batteries, the submarine is vulnerable to being inadvertently struck by surface vessels.
• The need to carry a large load of diesel fuel reduces space that might be used for weapons or other sorts of operations, such as underwater drones or teams of divers and their gear.
  

Anything that can improve on Diesel-Electric submarine battery performance will greatly enhance the mission capability of these very silent warships.  And so here we are with China considering replacing 100 year old battery technology with more modern technology.  If I were the one making the decisions, I'd tell them to forget about it until the technology is more mature, but it's not my call.

As a reminder, there have been numerous high-profile problems with lithium batteries, in nearly every instance of their use.

The Boeing 787 Dreamliner has experienced a few on-board fires with their lithium batteries, one of which led to an emergency evacuation.

Tesla electric cars have experienced several notable fires that did not even involve a prior collision.

Vape pens or E-cigarettes are notorious for occasionally going up in flames.

https://youtu.be/ImSbVwqbJRM?t=74

https://www.youtube.com/watch?v=a5EdtlfkpHc 

https://www.youtube.com/watch?v=iWxKM10JCaA

Personal Electronics:

The Samsung Note 7 was recalled in 2016 due to a number of battery fires.

Industrial:

A Tesla Megapack battery that stores energy for peaking use on the electrical grid in Australia went up in flames.

More to the point on the submarine front:  Not that long ago, I made a post about the Russian Federation's submarine Losharik losing half of its crew due to a lithium battery fire in the main storage battery.  This was a tragic event, and one that a lesson should be learned from.

The lesson is this:  If you are stuck in a vehicle that you can't readily exit, it's best not to be trapped inside with a lithium battery.  From a safety perspective, the weight and power advantage does not seem to justify the use of lithium batteries in aircraft and submarines.  At least with a flaming car, you can usually manage to pull over and escape before the vehicle is engulfed.  With a jet or a sub, probably not so much.