The Indian Navy's pursuit of fuel cell-based Air Independent Propulsion (AIP)-equipped conventional submarines is moving forward, albeit slowly. Currently, the Navy is evaluating two submarines for its advanced diesel-electric submarine needs, but only one has proven and validated technology. The Indian Navy is conducting field evaluation trials of the AIP technology developed by Spanish shipbuilder Navantia at Cartagena.
This technology has yet to be integrated into the S80 submarine offered to the Indian Navy, although a submarine of this class has already been inducted into the Spanish Navy without AIP technology. Navantia claims that its submarine design meets 'almost' all technical requirements of the P-75I without needing redesign.
Navantia's AIP system for the S80 produces over 300 kW of power, which can be directly applied to P75(I) without scaling up, thus reducing major risks for the Indian Navy. Factory testing of the AIP technology has been completed, simulating actual submarine mission conditions at the Cartagena Shipyard.
Navantia states that the S80 offered to the Indian Navy incorporates the latest technologies, such as Generation BEST AIP (Bio-ethanol Stealth Technology) and an advanced sensor suite. This third-generation AIP system uses hydrogen produced on board from bioethanol instead of stored hydrogen, allowing submarines to sail for up to three weeks submerged with minimal detectable signatures.
The Indian Navy also requires AIP technology combined with Lithium-ion batteries, enabling submarines to operate at high speeds without compromising their position. Navantia and its Indian partner, Larsen and Toubro (L&T), are not collaborating with another partner for proven Lithium-ion battery technology for this project.
Navantia's first submarine equipped with AIP BEST technology is expected to be operational by 2026. However, experts estimate that the AIP system will be ready for operational deployment in about three years, pending further laboratory tests and simulations.
Another submarine under consideration by India is already proven and used by several frontline navies. Recently, a submarine from this class completed a rare voyage under the Arctic ice. This submarine, the ArpĆ£o (S161), built by Howaldtswerke-Deutsche Werft (HDW) in Germany, is based on the export-optimized Type 214 design.
ThyssenKrupp has offered India its 214-class submarines, which combine advanced technologies from the 212 CD submarines with the latest AIP developments. These submarines, tailored to the Indian Navy's requirements, will feature Lithium-ion batteries, advanced sensor and combat systems, and enhanced stealth capabilities.
The 212 and 214-class submarines' AIP technology, powered by hydrogen fuel cells, allows for extended submerged operations and silent running, enhancing stealth. These submarines can operate silently, launch torpedoes stealthily, and have countermeasures against torpedoes, providing increased operational flexibility.
The Indian Navy is currently strengthening its undersea fleet, as evidenced by a recent exercise in the Arabian Sea involving eight submarines. Despite challenges such as dwindling fleet numbers and aging submarines, the Navy is pushing forward with plans to build six more conventional diesel submarines under Project-75 I.
However, the Chinese Navy's rapid expansion poses a significant challenge. China has been continuously deploying at least one nuclear-armed submarine at sea and is providing advanced submarine technology to Pakistan. In response, the Indian Navy is enhancing its capabilities to maintain strategic balance in the region.
The Indian Navy's adoption of AIP technology will enhance its fleet's capabilities, putting it in a better position against regional threats. While the Navy considers whether to proceed with proven technology or wait for the deployment of Navantia's AIP BEST technology on an operational submarine, the decision will significantly impact India's undersea defense strategy.