NEW DELHI: India has moved a step closer to having its conventional diesel-electric submarines equipped with air-independent propulsion (AIP) technology, which will enhance their underwater endurance and stealth, even as the third Scorpene submarine is all set to be commissioned at Mumbai on Wednesday.
The DRDO on Tuesday said it had achieved “an important milestone” in the development of the indigenous AIP system by proving its land-based prototype. Developed by the Naval Materials Research Laboratory (NMRL) of DRDO with the support of industry partners L&T and Thermax, the AIP system was operated in endurance mode for 14 days and maximum power mode for two days.
The 270 Kilowatt fuel cell-based AIP system will begin to be progressively retrofitted on the Scorpene submarines, which will involve adding an additional hull section to each boat, after the first one comes for a maintenance and refit upgrade after 2023-2024.
There is some concern at the huge delay in the AIP project, which was originally slated for completion by June 2017 after being sanctioned in 2014 with an initial cost of Rs 270 crore.
Unlike nuclear submarines, which have virtually unlimited underwater endurance, diesel-electric boats have to surface or snorkel every few days to get oxygen to recharge their lead-acid batteries.
But those fitted with AIP can stay submerged for longer periods to significantly boost their stealth and combat capabilities. Some countries like Japan, however, are already moving towards high capacity lithium-ion batteries to eventually replace AIP systems for their conventional submarines. The US, of course, operates only nuclear-powered submarines.
The DRDO, on its part, said that while there are different types of AIP systems being pursued internationally, the fuel cell-based one of NMRL is “unique” as the hydrogen is generated onboard. “The AIP system has now reached the stage of maturity for fitment into target vessels,” said an official.
The development comes even as the third Scorpene submarine is set to be commissioned as INS Karanj on Wednesday. Under the over Rs 23,000 crore ‘Project-75’ underway at Mazagon Docks for construction of six French-origin Scorpene submarines, the Navy has commissioned two vessels, INS Kalvari and INS Khanderi, till now.
The fourth submarine called Vela, which was launched in May 2019, has commenced its sea trials, while the fifth, Vagir, was launched last November. The sixth, Vagsheer, in turn, is currently in an advanced stage of construction.
Though the Scorpene project has faced huge time and cost overruns, it is critical for the Navy since it currently has just 12 other ageing diesel-electric submarines, with just half of them operational at any given time.
India also has two nuclear-powered submarines, INS Arihant and INS Chakra, but the latter does not have nuclear-tipped ballistic missiles because it has been acquired on lease from Russia.
India needs at least 18 conventional submarines, six nuclear-powered attack submarines (SSNs) and four nuclear-powered submarines with nuclear-tipped missiles (SSBNs).
As earlier reported by TOI, the defence ministry is now also getting set to formally launch the long-pending over Rs 42,000 crore project to construct six new-generation stealth submarines with foreign collaboration domestically.
Under this ‘Project-75 India’, the six new submarines will have land-attack cruise missiles as well AIP. But it will take almost a decade from now for the first such submarine to roll out.