Why is it in the News?

The Indian Navy has initiated trials to modernize its conventional submarine fleet by issuing a Rs 60,000 crore tender for the acquisition of highly advanced submarines equipped with Air Independent Propulsion (AIP) technology.

What is an Air Independent Propulsion (AIP)?

• Air Independent Propulsion (AIP) is a propulsion system used in submarines that allows them to operate underwater for extended periods without the need to surface or snorkel for air.
• Unlike traditional diesel-electric submarines, which rely on diesel engines for surface propulsion and battery-powered electric motors for submerged propulsion, AIP-equipped submarines use a supplementary propulsion system that generates power independently of atmospheric oxygen.
• AIP systems typically employ technologies such as fuel cells, closed-cycle diesel engines, Stirling engines, or other innovative methods to generate electricity or mechanical power for propulsion while submerged.
  • Closed Cycle Diesel Engines: These engines use stored liquid oxygen and an inert gas, such as argon, to run the diesel engine while submerged.
  • Closed Cycle Steam Turbines: These systems generate steam using stored liquid oxygen and a fuel source, such as diesel or bioethanol, to power a turbine and produce electricity.
  • Stirling Cycle Engines: This technology utilizes a closed-cycle heat engine to generate power using a temperature difference between a hot and cold source.
  • Fuel Cells: These devices convert chemical energy from a fuel, such as hydrogen, and an oxidizing agent, like stored liquid oxygen, into electrical energy through an electrochemical reaction.
• These systems produce minimal noise and exhaust, allowing submarines to operate quietly and stealthily underwater, making them less vulnerable to detection by sonar and other detection systems.
• The implementation of AIP technology significantly enhances the stealth and endurance capabilities of submarines, enabling them to conduct longer-duration covert missions and remain submerged for extended periods, thereby enhancing their overall operational effectiveness.
• The Defence Research and Development Organisation (DRDO) is pioneering fuel cell-based AIP systems, unique for their hydrogen generation capabilities.
• Developed by the Naval Materials Research Laboratory (NMRL) of DRDO, these systems offer flexibility in operation modes to meet diverse user requirements.