DRDO’s indigenous Air Independent Propulsion (AIP) Energy Module has entered “Setting to Work Phase-2”, the stage before it is switched on to produce power. The module was developed by DRDO’s Naval Materials Research Laboratory (NMRL). It will be energised and tested to Indian Navy protocols, then handed to Mazagon Dock Shipbuilders Limited (MDL) for integration on a Kalvari-class submarine in early 2027. The activity was inaugurated at Larsen & Toubro’s Hazira complex in Gujarat on 24 October 2026.
Exam concepts
Why submarines need AIP: A conventional (diesel-electric) submarine runs on batteries underwater. Every few days it must surface or raise a snorkel to run its diesel engines, which need atmospheric oxygen. That is when it is easiest to detect.
What AIP does: AIP lets a submarine make power underwater without outside air, so it can stay submerged much longer.
DRDO’s technology: The system is based on a phosphoric acid fuel cell that generates its hydrogen on board.
Nuclear submarines: Nuclear-powered submarines (SSN, SSBN) do not need AIP, because a reactor needs no oxygen.
Kalvari class: The six Kalvari-class boats are French Scorpene-design submarines built by MDL under Project-75.
Key facts for quick revision
- Developer: Naval Materials Research Laboratory (NMRL), DRDO
- Stage: Setting to Work Phase-2 (before energising)
- Integration: Kalvari-class submarine (Project-75), early 2027, by Mazagon Dock Shipbuilders Limited
- Venue: L&T’s AM Naik Heavy Engineering Complex, Hazira, Gujarat, 24 October 2026
Source: PIB, Ministry of Defence
