- Recently, France’s Naval Group declined the bid for the P-75I Project, citing it does not use AIP (Air-Independent Propulsion) Technology yet.
- Around 10 countries have developed or are close to building AIP technology, and almost 20 nations have AIP submarines.
- In June 1999, the Cabinet Committee on Security approved a 30-year plan for the Navy to indigenously build and induct 24 submarines by 2030.
- In the first phase, two lines of production were to be established — the first, P-75; the second, P-75I. Each line was to produce six submarines.
- While the six P-75 submarines are diesel-electric, they can be fitted with AIP technology later in their lives.
- This P-75I project envisages indigenous construction of submarines equipped with the state-of-the-art Air Independent Propulsion system at an estimated cost of Rs. 43,000 crore.
- AIP is a technology for conventional non-nuclear submarines.
- 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 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 – DRDO), is considered one of the ambitious projects of the DRDO (Defence Research and Development Organisation) for the Navy.
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 emission of sound.
Advantages and Disadvantages of AIP
Advantages:
- AIP has a force multiplier effect on lethality of a diesel electric submarine as it enhances the submerged endurance of the boat several fold.
- Fuel cell-based AIP has merits in performance compared to other technologies.
- AIP technology allows a conventional submarine to remain submerged for much longer than ordinary diesel-electric submarines.
- All conventional submarines have to surface to run their generators that recharge the batteries that allow the boat to function under water.
- However, the more frequently a submarine surfaces, the higher the chances of it being detected.
- AIP allows a submarine to remain submerged for more than a fortnight, compared to two to three days for diesel-electric boats.
Disadvantages:
- Installing AIP increases the length and weight of the boats, requires pressurised liquid oxygen (LOX) storage on-board and supply for all three technologies.
- MESMA (Autonomous Submarine Energy Module) and the Stirling engine have some acoustic noise from moving parts; and the submarine’s unit cost increases by around 10%.
- What submarines does India have now?
- India has 16 conventional diesel-electric submarines, which are classified as SSKs. After the last two Kalvari Class subs are commissioned under P-75, this number will go up to 18.
- India also has two nuclear ballistic submarines, classified SSBN (Submersible Ship Ballistic Missile Nuclear).
- By the time P-75I is completed under the 30-year project, India is projected to have six diesel-electric, six AIP-powered, and six nuclear attack submarines.
SOURCE: THE HINDU,THE ECONOMIC TIMES,MINT