India Set to Integrate Indigenous Air-Independent Propulsion System on INS Khanderi in 2026
In a significant advancement for India's naval indigenization efforts, the Indian Navy is set to integrate its first indigenous Air-Independent Propulsion (AIP) system into the Kalvari-class submarine INS Khanderi during a refit planned for July 2026, according to defense sources.
The AIP system, developed by the Defence Research and Development Organisation (DRDO) in collaboration with Larsen & Toubro (L&T) and Thermax, marks a substantial innovation in undersea warfare technology. This advancement allows conventional submarines to remain submerged for extended periods without needing to surface or snorkel for battery recharging.
The prototype of the AIP system is anticipated to be completed by December 2025, with sea trials set to commence in early 2027. Upon successful validation, the system will be retrofitted into other Scorpene-class submarines and incorporated into all future conventional submarines as part of upcoming projects.
Distinct from foreign AIP systems, India’s version utilizes hydrogen-on-demand technology, which generates hydrogen inside the submarine rather than storing it. This design improves safety and simplifies logistics. Based on fuel cell technology, it also produces water as a by-product, promoting sustainability and environmental friendliness.
According to defense experts, the indigenous AIP will serve as a “force multiplier”, significantly enhancing stealth, endurance, and combat capability while reducing dependency on expensive nuclear propulsion. This integration will position India among a select group of nations, including Germany, France, and Japan, that have mastered AIP technology.
The Navy regards this project as crucial in addressing the growing submarine presence of regional adversaries in the Indian Ocean Region (IOR). Officials stress that timely implementation is vital, as the ability to maintain stealth and extended underwater presence is essential to India's maritime deterrence strategies.
