Air Independent Propulsion for Diesel Electric Submarines

• 10 Mar 2021

Why in News

The Defence Research and Development Organisation (DRDO) has conducted the final development test of Air Independent Propulsion (AIP) System, crucial for diesel electric submarines.

Key Points

• Air Independent Propulsion (AIP) System:
  
  • Submarines are essentially of two types: conventional and nuclear.
  • The conventional submarines use diesel-electric engines, which require them to surface almost daily to get atmospheric oxygen for fuel combustion.
  • If fitted with an Air Independent Propulsion (AIP) system, the submarine will need to take in oxygen only once a week.
  • The indigenously-developed AIP, which is one of the key missions of the Naval Materials Research Laboratory (NMRL), is considered one of the ambitious projects of the DRDO for the Navy.
    
    • The project aims at fitting the technology on India’s Scorpene class submarine INS Kalvari around 2023.
• Advantages of AIP:
  
  • The AIP system based submarines will be required to surface much less frequently, thus increasing their lethality and stealth multifold.
  • Diesel-electric submarines require them to come to the surface frequently to charge their batteries, thus their underwater endurance time is less.
    
    • ‘Air-independent’ propulsion technology helps to make the diesel generator less dependent on surface air.
  • While there are different types of AIP systems being pursued internationally, fuel cell-based AIP of NMRL is unique as the hydrogen is generated onboard.
• Fuel Cell Based AIP system:
  
  • In a fuel cell based AIP, an electrolytic fuel cell releases energy by combining hydrogen and oxygen, with only water as the waste product ensuring less marine pollution.
  • The cells are highly efficient, and do not have moving parts, thus ensuring that the submarine has a low acoustic emissions of sound.

Naval Materials Research Laboratory

• Naval Materials Research Laboratory (NMRL) is one of the laboratories functioning under DRDO, pursuing basic research as well as application-oriented technology development in several areas viz. Metallurgy, Polymer, Ceramics, Coating, Corrosion and Electrochemical Protection, Marine Biotechnology, Environmental Sciences.
• It’s mission:
  
  • To develop Air Independent Propulsion (AIP) systems for Naval Submarine & Fuel Cell technologies.
  • To provide scientific solutions for all categories of materials & related technologies for Indian Navy.
  • To undertake research projects on strategic materials for Indian Navy.

Nuclear Submarines versus Conventional Submarines

• The main difference between conventional submarines and nuclear submarines is the power generation system. Nuclear submarines (e.g INS Arihant, INS Akula) employ nuclear reactors for this task and conventional submarines (e.g Project-75 and Project-75I Class Submarines) use diesel-electric engines.
• While nuclear-powered submarines are considered as key assets for deep sea operations, the conventional diesel electric ones are vital for coastal defence and operations close to the shore.

Source: IE