Explained: DRDO's Air Independent Propulsion (AIP) System and its benefits for Indian Submarines

DRDO's AIP Technology: Why in  News?

DRDO has recently developed the AIP system which means the Indian submarines would be aided to stay for longer hours than before underwater. This test was done a day before INS Karanj attack submarine was inducted into Indian Navy. 

Raksha Mantri Shri @rajnathsingh has congratulated @DRDO_India , @indiannavy and the Industry for this significant achievement. https://t.co/4zsFBa8bO5

— रक्षा मंत्री कार्यालय/ RMO India (@DefenceMinIndia) March 9, 2021

What is an AIP System?

AIP stands for Air Independent propulsion test which allows any submarine to stay in water for longer hours and also makes the subsurface platform deadlier by decreasing the noise levels it makes while travelling making it hard to detect. 

DRDO achieved an important milestone in the development of AIP System by proving the land based prototype on 8 March 2021. The plant was operated in endurance mode and max power mode as per user requirements. AIP system is being developed by NMRL DRDO. #AatmanirbharBharat pic.twitter.com/Z9ux39XmlT

— DRDO (@DRDO_India) March 9, 2021

AIP Technology: Significance

1. The development of AIP technology is in line with Atma Nirbhar Bharat campaign 
2. This technology is only available with the US, France, China, UK and Russia. This brings India at par with them 
3. The last two Kalvari class submarines would be powered by the AIP technology
4. The AIP technology would make the Indian submarines more lethal. It would also take advantage of internal refraction that rises in the equatorial waters due to differences in temperatures within the ocean and on the surface. 

About DRDO's AIP Technology:

1. The system is being developed by Naval Materials Research Laboratory (NMRL) of DRDO.
2. DRDO’s AIP technology is based on a Phosphoric Acid Fuel Cell.
3. The marine propulsion technology allows many non nuclear submarines to function without accessing the atmospheric oxygen. 
4. This process is done through snorkelling or surfacing. 
5. The technology also augments the diesel electric propulsion system of attack submarines. 
6. All AIP fitted submarines do not have to surface for charging their batteries and can thus remain underwater for a longer duration.
7. An additional hull section has to be added to the existing submarine to get the benefits of the AIP system. 
8. AIP equipped submarines are called SSP while the diesel attack submarines are called SSK 
9. AIP uses various methods like closed cycle diesel, fuel cells, stirling engines, closed cycle steam to extend the durability of submergence under water.
10. The system consists of engine, fuel, means to use fuel without accessing atmosphere, a generator and a battery. 

Types of Submarines:

Diesel electric attack submarines

Nuclear powered attack submarines

India's unique factor 

India uses a fuel based AIP system which is unique as hydrogen is generated onboard from this type of system. This technology is being successfully developed with the support of industry partners L&T and Thermax. It has now reached a stage of maturity. 

Kalvari would be upgraded around 2023. India now stands among the nuclear fitted submarines possessing countries like China, France, Russia, United Kingdom and United States of America. 

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