DRDO Affirms Its Scalable AIP Tech Can Power India's Larger P-76 Subs, Offering Cost-Effective 90% Indigenisation

The Defence Research and Development Organisation (DRDO) has reinforced its confidence in the scalability of its indigenous Air-Independent Propulsion (AIP) technology, confirming its readiness to power India’s next-generation Project-76 (P-76) submarines.

While originally designed for the compact Kalvari-class (Scorpene) vessels, DRDO sources state the fuel-cell-based system is fully adaptable for larger platforms, promising enhanced stealth and endurance for the Indian Navy’s future underwater combatants.

Scalable Power for Blue Water Ambitions​

The Naval Materials Research Laboratory (NMRL), a premier DRDO lab, has successfully validated its Phosphoric Acid Fuel Cell (PAFC) technology—a variant of the fuel-cell system mentioned in initial reports—proving its capability to generate hydrogen on board

While the system was initially tailored for the 1,800-ton Kalvari-class submarines, officials emphasize that the technology is not limited by size.

According to recent internal reviews, the AIP system features a modular architecture. This design allows the fuel-cell stacks to be configured in parallel to meet higher power requirements.

"The technology is inherently scalable. By increasing the number of fuel-cell stacks and refining the thermal management systems, we can seamlessly adapt the propulsion to meet the rigorous demands of the Navy’s blue-water operations," a DRDO spokesperson stated.

Project-76: A Quantum Leap in Capability​

Project-76 represents a massive stride towards self-reliance (Atmanirbhar Bharat) in maritime defence.

Envisioned as a fully indigenous conventional submarine programme with an estimated budget of ₹1.2 lakh crore, these vessels will significantly outperform their predecessors.

Unlike the compact Kalvari-class, the P-76 submarines are expected to have a submerged displacement of 3,000 to 4,000 tons. This 40% increase in size is designed to accommodate:

• Advanced Vertical Launch Systems (VLS) capable of firing BrahMos supersonic cruise missiles.
• Extended crew endurance for long-range Indo-Pacific deployments.
• High-performance sensor suites and electronic warfare systems.

To sustain these energy-intensive systems, the upscaled AIP configuration is projected to deliver outputs exceeding 200 kW, doubling the capacity of the current 100-120 kW modules designed for the Kalvari class.

Operational Superiority and Strategic Necessity​

The integration of AIP is a game-changer for conventional diesel-electric submarines. It allows them to recharge their batteries without surfacing for atmospheric oxygen, a vulnerability that often exposes submarines to enemy radar.

With the enhanced AIP system, P-76 submarines are targeted to achieve submerged endurance of 4 to 5 weeks at low speeds. This capability is critical for shadowing operations in strategic choke points such as the Malacca Strait and the Arabian Sea.

The technology has already undergone rigorous validation, with land-based prototypes demonstrating reliability and a module slated for integration into INS Kalvari during its upcoming refit, expected around 2025-26.

Pushing for 90% Indigenisation​

A key tenet of Project-76 is its high level of indigenisation.

DRDO is collaborating closely with Indian industry majors, including Larsen & Toubro (L&T) and Tata, to scale the production of AIP components.

This partnership aims to achieve up to 90% local content by the time the submarines are inducted, drastically reducing lifecycle costs and dependence on foreign OEMs.

This development comes at a critical time for Indian security. The Indian Ocean Region is witnessing increased underwater activity, notably from the proliferation of China’s Type 039A Yuan-class AIP submarines and the upcoming supply of Hangor-class vessels to Pakistan.

Project-76, alongside India’s nuclear-powered ballistic missile submarines (SSBNs), serves as a vital component in countering these emerging threats and fortifying the nation's maritime borders.

 

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[Pirthpall Sekhon]

India needs to get additional funding from Canada, Australia and the UK to allow it to recruit vast pools of youngsters into further growth in these technologies. We have to start assisting others by building submarines or upgrading them for their requirements. Let's as a first step set up Indian building entities in our allies territory.
Another future commercial enterprises could be approaching Nicaragua to provide us with ports on both the gulf and Pacific coastlines and our Directorate of Merchant Navy corporations could get into the lucrative Pacific / Atlantic container traffic business. We need to simultaneously invest in commercial enterprises to earn higher income necessary for paying to create top notch scientific discoveries.