Japan has added a new dimension in submarine technology. It’s a benchmark of sorts, a game changer, a disrupter which could lead to a ‘race’ in the Indo-Pacific as new-tech submarines would acquire an edge over the existing technology
The Japan Maritime Self Defence Force (JMSDF) commissioned a ‘conventional submarine’ that runs on Lithium Ion batteries — the same battery technology which powers laptops, mobile phones etc.
‘Conventional submarines’, since world war II ( 1939 -1945) , have used ‘lead-acid’ batteries which are heavier than the Lithium batteries and are less energy efficient. Lithium ion batteries allow submarines to remain underwater for longer periods extending their efficacy, much need during conflict.
Conventional vessels also known as Diesel-electric submarines, use batteries for underwater propulsion. The adoption of lithium ion batteries instead of lead-acid by the Japanese is a jump over existing technology and eventually puts pressure on other navies, especially China and India, the other two Asian biggies, which are still on lead-acid batteries for conventional submarines.
Japan disrupts with technology
This technology disruption by Japan will result in a new generation of submarines that are deadlier than ever, stay underwater for longer period and are quieter than before. Anti-submarine specialists will face a tough times in detecting submarines, which any way are considered the toughest to locate when submerged.
On March 5, Japan commissioned the new submarine SS 511 ‘Ouryu’ meaning the ‘Yellow dragon’. Made by the Mitsubishi Heavy Industries, this is the sixth Soryu-class boat to be built by MHI. Kawasaki Heavy Industries is making the other six of the same Soryu-class and the last boat, from the KHI stable called the SS 512 Toryu ( Dragon slayer) will also have Lithium ion batteries.
The two subs carry Lithium Nickel Cobalt Aluminum Oxide, or NCA batteries. These need less maintenance time and is capable of longer endurance at high speeds when submerged. Japanese major GS Yuasa is the maker of these batteries.
It has a shorter charging time and longer lifespan, the latter would save costs as it entails fewer battery changes over the lifespan of the submarine.
The previous boats of the Soryu class have been fitted with two Kawasaki 12V 25/25 diesel generators and four Kawasaki Kockums V4-275R Stirling air-independent propulsion (AIP) engines. The first ten of the Soryu-class boats use lead-acid batteries for energy storage.
Each Soryu-class Subs displace 4,200 tonnes submerged. It measures just under 275 feet in length. Each boat is equipped with six torpedo tubes and can carry up to 30 21-inch heavyweight torpedoes, Harpoon anti-ship missiles or mines.
The Lithium edge
Lithium ion batteries are lighter and will provide longer underwater propulsion. They have a higher energy density, a pound of lithium ion batteries will store more electricity than a pound of lead acid. Lithium ion batteries hold their charge longer and rapid charged.
Lithium ion batteries also carry a risk as it can catch a fire when exposed to water. In the event of a leak, batteries have to shielded from water at all costs. Lithium is known to burn at up to 3,600 degrees Fahrenheit, and release hydrogen gas.
Technically, all diesel-electric submarines use batteries to travel silently underwater. The batteries are charged by a diesel engine, which needs oxygen to run. For this process of charging, the submarine needs to surface, or atleast put out its periscope for air intake above the surface of water and also an exhaust port above the surface. The Lithium ion battery will reduce the frequency of surfacing ( from the existing once in 3-4 days) and also the time a sub is surfaced.