The Taigei and the other future submarines in its class are just one part of Japan’s broader efforts to bolster its defenses in response to growing regional security concerns. Credit:

After a decade of heavy R&D, Japan has officially launched a new type of diesel-electric submarine, driven by an innovative propulsion system using lithium-ion batteries.

While the two most recent examples of Japan’s Soryu class are fitted with a similar powerplant, the Taigei, which means “Big Whale” in Japanese, is the first of a class to feature it from the outset, The War Zone reported.

Currently, only Japan is known to have operational submarines with lithium-ion batteries.

The Taigei was launched on October 14, 2020, at the Mitsubishi Heavy Industries (MHI) shipyard in the city of Kobe, in the western prefecture of Hyogo, The War Zone reported.

The ceremony was attended by Japan’s Minister of Defense Nobuo Kishi, Japan Maritime Self-Defense Force (JMSDF) chief Hiroshi Yamamura and about 150 guests. 

The 3,000-ton submarine is slated to go into service as the 22nd vessel in the Maritime Self-Defense Force’s (MSDF) submarine fleet in March 2022, reported.

Tokyo has been planning to boost the number of its subs from 16 to 22 under plans laid out in its National Defense Program Guidelines in 2010.

Japanese officials launch the Taigei submarine at Kobe shipyard. Defense Minister Nobuo Kishi, MSDF Chief of Staff Hiroshi Yamamura and around 150 others attended the ceremony. Credit: Twitter.

The vessel is 84 meters in length and 9.1 meters in width and comes with a price tag of around 76 billion yen (about US$722.23 million) to build, the MSDF said, adding that the incorporation of lithium-ion batteries allow the vessel to remain under water for longer than previous models, reported.

It will be able to house 70 crew members. The JMSDF also noted that the new sub will offer a “suitable environment for female submariners,” after the first woman entered the Japanese submariners’ academy earlier in 2020, The War Zone reported. 

Charging is also said to be quicker and battery life longer compared to lead-acid batteries, which have to be repeatedly recharged by running the diesel engines.

The lithium-ion cells are also less bulky and have reduced maintenance requirements, The War Zone reported. 

The drawback is cost — lithium-ion batteries are more costly than the lead-acid alternative.

In the past, the JMSDF provided a construction cost of US$488 million for a standard Soryu-class boat, as opposed to US$608 million for the first of the lithium-ion subvariants, The War Zone reported.

A key consideration was further reducing the submarine’s acoustic signature by eliminating the many moving parts typically found in AIP systems (Air Independent Propulsion technology), which are already generally very quiet, War Zone journalist Tyler Rogoway reported.

In principle, this would result in an exceptionally quiet boat, making it very hard for opponents to detect and track, but with the added advantage of being able to accelerate much more rapidly while submerged than existing AIP submarines.

According to the MSDF, Japan currently operates nine 2,750-ton Oyashio-class submarines and 11 2,950-ton Soryu-class warships, reported.

The MSDF is planning to introduce a 12th Soryu-class sub next year, it said.

JMSDF submarine Soryu is pulled away from a submarine tender off the island of Guam. The last two boats in its class are already equipped with lithium-ion batteries, which are more efficient but also more expensive. Credit: US Navy.

Japan is still bound by the constraints of its pacifist constitution, Article 9 of which states that the “Japanese people forever renounce war as a sovereign right of the nation and the threat or use of force as means of settling international disputes.”

“In order to accomplish the aim of the preceding paragraph, land, sea, and air forces, as well as other war potential, will never be maintained. The right of belligerency of the state will not be recognized,” the key pacifist article in the constitution reads.

Nevertheless, at the end of last month, Japan’s Defense Ministry requested a record 5.49 trillion yen (about US$52.17 billion) budget for the fiscal year starting in April 2021, with the request rising 3.3% from the initial budget for the current fiscal year through March 2021, reported.

With the ministry eyeing allocations for enhancing capabilities in outer space, cyberspace as well as financing for land-based infrastructure and hardware, Japan’s defense spending under new Prime Minister Yoshihide Suga is expected to rise for the ninth straight year.

— with files from The War Zone,