One of the two AIP, which has been so far tested only on the ground, will be refitted on a Kalvari class of submarine of Indian Navy and the other would be navalised for the DRDO for future R&D

Larsen & Toubro (L&T) and Defence Research and Development Organisation (DRDO) has signed a contract for re-fitment of two Air Independent Propulsion (AIP) System modules for Kalvari class of submarines of the Indian Navy.

These modules constitute the core of the fuel cell based AIP System, critical for increasing the endurance of conventional submarines. It has been indigenously developed by Naval Materials Research Laboratory (NMRL) of the DRDO with L&T as prime industry partner, said the leading private defence manufacturer in an official statement on Thursday.

“The energy modules (EMs) comprising fuel cells produce the required power, along with on-board Hydrogen generation. The technology of this indigenous AIP system is a unique one that generates hydrogen on demand thereby obviating the need for carrying hydrogen onboard which is a major safety concern for a submarine,” read the L&T statement.

The contract documents were signed and exchanged last week between Arun T Ramchandani, Executive Vice President and Head-L&T Defence and PT Rojatkar, Director, Naval Materials Research Laboratory (NMRL) of the DRDO. JD Patil, Member of Executive Committee of Management and Advisor (Defence & Smart Technologies) to CEO and MD Larsen & Toubro Ltd and senior officials from NMRL were also present at the event.

The pioneering effort by the DRDO and L&T to indigenously develop AIP system has propelled India into an elite league of two countries — Germany and South Korea — which have their own modules. “We are proud to be the longest serving development partner to DRDO across programs in multiple domains. L&T is privileged to be associated with accomplishing the dream of realising an indigenous AIP system and mark India‘s joining a select group of few nations who have developed the requisite technology,” Arun Ramchandani said on the core technology project which acquired shape over 12 long years of R&D by the DRDO. It transferred the technology to the L&T in 2021.

Elaborating on the agreement, L&T’s JD Patil said, “We are supposed to deliver two AIPs in less than two years and one of them will be refitted on a Kalvari class of submarine built by Mazagon Dock Shipbuilders Limited (MDL) for Navy”.

Sources stated the other AIP would be navalised for the purpose of future R&D by the DRDO since the existing module has been successfully tested just on the ground. So far, MDL has built five Kalvari class diesel-electric submarines INS Kalvari, INS Khanderi, INS Karanj, INS Vela and INS Vagsheer — and the sixth one under ‘75 India’ project is in the pipeline.

The first refit cycle of a submarine under use by the Navy would end by early 2026 which would give a window to integrate the EMs into the AIP Plug on the maritime platform.

The company stated that the manufacturing, integration and factory acceptance trials of the EMs will be undertaken in L&T’s AM Naik Heavy Engineering Complex at Surat. “This project would pave the way for order(s) for AIP Systems for the remaining five Kalvari Class submarines in the coming years. This could also open up possible export opportunities to other countries that operate Scorpene class submarines,” stated L&T.