L&T and DRDO sign pact for submarine propulsion system

Subject : Science and technology

Section: Defence

Concept :

Larsen & Toubro (L&T) and the Defence Research and Development Organisation (DRDO) have signed a contract for the realisation of two Air Independent Propulsion (AIP) System Modules for the Kalvari Class of submarines of the Indian Navy.
The Air Independent Propulsion (AIP) module extends the endurance of conventional submarines and is a niche technology.

AIP Technology:

AIP refers to Air-Independent Propulsion, a technology for conventional— that is, non-nuclear — submarines.
There are different types of AIP mechanisms available; what India is looking for under the P-75I project is AIP based on fuel cells. These cells convert chemical energy into electrical energy, recharging the batteries of the submarine.
The Air Independent Propulsion (AIP) modules are said to be the core of the fuel cell-based AIP System, indigenously developed by the Naval Materials Research Laboratory of the DRDO with L&T as the prime industry partner.
The Energy Modules comprising fuel cells produce the required power, along with onboard hydrogen generation.
AIP has a force multiplier effect on lethality of a diesel electric submarine as it enhances the submerged endurance of the boat several folds.
Diesel electric submarines must come to the surface or close to it (2-3 days) to run their generators to recharge the batteries that propel them under water. AIP is a mechanism that allows the batteries to be charged even while the boat is submerged. However, even with AIP, the submarine needs to surface every three weeks or so (14 days).
While the six P-75 submarines are diesel- electric, they can be fitted with AIP technology later in their lives. By the time P-75I is completed under the 30-year project, India is projected to have six diesel-electric, six AIP-powered, and six nuclear attack submarines (yet to be built).