Air Independent Propulsion submarines (Indian Express)

Mains Paper 3: Defense and Security
Prelims level : Air Independent Propulsion
Mains level : Significance of the Air Independent Propulsion submarines

Context

•  It has been witnessing operation of land-based prototype of DRDO India Air Independent Propulsion system at Naval Materials Research Laboratory in Ambernath.
•  The DRDO on Wednesday tested a land-based prototype of an Air Independent Propulsion (AIP) submarine.
•  The prototype operation at the Naval Materials Research Laboratory in Ambernath, Maharashtra, is considered to give a boost to the DRDO’s plan to build AIP systems for Indian naval submarines.
•  The land-based prototype was engineered to the form-and-fit of a submarine.

Air-independent propulsion

•  Air-independent propulsion (AIP) is any marine propulsion technology that allows a non-nuclear submarine to operate without access to atmospheric oxygen (by surfacing or using a snorkel).
•  AIP can augment or replace the diesel-electric propulsion system of non-nuclear vessels.

What is the Air Independent Propulsion (AIP) technology used in submarines?

•  Submarines are essentially of two types: conventional and nuclear.
•  Conventional submarines use a diesel-electric engine, and must surface daily for oxygen for fuel combustion. If fitted with an Air Independent Propulsion (AIP) system, the sub needs to take in oxygen only once a week.
•  Many naval powers, including India, have acquired nuclear-powered submarines for deep-sea operations, conventional diesel-electric variants are considered useful for coastal defence.
•  The latter are optimised for stealth, and their weapons and sensors provide for effective operations close to the shore.
•  Because diesel-electric submarines require to come to the surface frequently to charge their batteries, their underwater endurance time is less.
•  ‘Air-independent’ propulsion technology helps to make the diesel generator less dependent on surface air.
•  In a fuel cell AIP, an electrolytic fuel cell releases energy by combining hydrogen and oxygen, with only water as the waste product.
•  The cells are highly efficient, and do not have moving parts, thus ensuring that the submarine has a low acoustic signature.
•  Older submarines can be adapted to the AIP system by retrofitting.
•  A fuel cell-based AIP, like the one developed by DRDO, is known to deliver better performance compared to other technologies.
•  According to the Defence Ministry press release, the AIP system enhances the submerged endurance of diesel-electric submarines several times, thus having a multiplier effect on its lethality.

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Prelims Questions:

Q.1) With reference to the Programme for International Student Assessment (PISA), consider the following statements:
1. It is a triennial international survey which was first administered in 1980.
2. It is coordinated by the Organization for Economic Cooperation and Development (OECD).

Which of the statements given above is/are correct?

a. 1 only
b. 2 only
c. Both 1 and 2
d. Neither 1 nor 2

Correct Answer: B
Mains Questions:
Q.1) Define Air-independent propulsion. What is the Air Independent Propulsion (AIP) technology used in submarines?