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05 May 2022 Air-Independent Propulsion (AIP)

Posted at 13:12h in Daily current-affairs by khyati khare 0 Comments

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Recently France’s Naval Group rejected the bid for the P-75 India project, saying it does not yet use Air-Independent Propulsion (AIP) technology.
About 10 countries have developed or are nearing to develop AIP technology and about 20 countries have AIP submarines.

In June 1999, the Cabinet Committee on Security (CCS) approved a 30-year submarine building plan that included building 24 conventional submarines by 2030.
In the first phase, two series of production were to be established – the first, the P-75; Second, the P-75i. Each series was to produce six submarines.
While the six P-75 submarines are diesel-electric, they can be equipped with AIP technology later.
The project envisages indigenous construction of six conventional submarines equipped with state-of-the-art air-independent propulsion systems at an estimated cost of Rs 43,000 crore.

AIP is the technology for conventional non-nuclear submarines.
There are essentially two types of submarines: conventional and nuclear.
Conventional submarines use diesel-electric engines, which require them to surface daily to obtain atmospheric oxygen for fuel combustion.
If the submarine is equipped with an AIP system, they will need to take oxygen only once a week.
Indigenously developed AIP is one of the major missions of Naval Materials Research Laboratory (NMRL-DRDO), which is considered as one of the ambitious projects of DRDO (Defence Research and Development Organisation) for Navy.

In fuel cell based AIP, the electrolytic fuel cell produces energy only by combining hydrogen and oxygen with water, thereby generating less marine polluting waste products.
These cells are highly efficient and do not have moving parts, thus ensuring that the submarine has less noise emissions.

AIP has a force multiplier effect on the firepower of a diesel electric submarine as it multiplies the underwater capability of the boat.
Fuel cell based AIP performs better than other technologies.
AIP technology keeps a conventional submarine submerged for longer than normal diesel-electric submarines.
All conventional submarines have to come to the surface to run their generators, which recharge their batteries and enable the boat to function underwater.
However, the more often a submarine comes to the surface, the more likely it is to be monitored by enemies.
AIP is able to keep a submarine underwater for around 15 days, compared to two to three days by diesel-electric boats.

Installing AIP increases the length and weight of boats, requiring onboard pressurized liquid oxygen (LOX) storage and supplies for all three technologies.
Some acoustic noise is generated from the moving parts of the MESMA (Autonomous Submarine Energy Module) and Stirling engine, which increases the unit cost of the submarine by about 10%.

India has 16 conventional diesel-electric submarines, classified as SSKs. With the commissioning of the last two Kalvari class submarines under the P-75, this number will increase to 18.
India also has two nuclear ballistic submarines classified as Submersible Ship Ballistic Missile Nuclear-SSBN.
India is estimated to have six diesel-electric, six AIP-powered and six nuclear strike submarines by the time the P-75I is completed under the 30-year project.