Larsen & Toubro (L&T) and Spanish shipbuilder Navantia are collaborating on a significant project to supply six Air-Independent Propulsion (AIP) submarines to the Indian Navy under the Project 75(I) program. This partnership aims to enhance the capabilities of the Indian Navy's submarine fleet, allowing for longer submerged operations and improved stealth features.

The Project 75(I) program aligns closely with India's strategic partnership model, which aims to enhance indigenous defence manufacturing capabilities while fostering collaboration with foreign technology partners.

Here Are The Key Aspects of Project 75(I) Program

The  aligns closely with India's strategic partnership model, which aims to enhance indigenous defence manufacturing capabilities while fostering collaboration with foreign technology partners.

The P75(I) program is a significant initiative under the "Make in India" campaign, focusing on the indigenous construction of six conventional submarines. This approach aims to build India's self-reliance in defence manufacturing by developing local capabilities in submarine design and production.

The program is the first major procurement under the Strategic Partnership (SP) model, which was introduced to facilitate collaboration between Indian private sector firms and leading foreign original equipment manufacturers (OEMs). This model mandates that Indian companies partner with foreign firms to co-develop and manufacture advanced military platforms, thereby ensuring technology transfer and capacity building within India.

Foreign OEMs participating in the P75(I) project are required to provide technology transfer to their Indian partners. This transfer includes critical technologies related to submarine design, construction, and maintenance, which is essential for enhancing India's defence capabilities and reducing dependency on foreign suppliers.

The project is expected to create a robust industrial ecosystem around submarine manufacturing in India, benefiting not just large defence firms but also small and medium enterprises (SMEs) involved in the supply chain. This ecosystem will support the development of associated systems, equipment, and spares necessary for submarine operations.

By progressively building indigenous capabilities through projects like P75(I), India aims to meet its broader national defence objectives, including enhancing naval strength and ensuring security in the Indo-Pacific region amidst rising regional threats. 

The project, valued at approximately ₹40,000 crore (around $5.8 billion), is one of India's largest defence acquisition initiatives. It not only aims to strengthen military capabilities but also contributes significantly to economic growth by creating jobs and promoting technological advancements within the country.

L&T And Navantia Collaboration

L&T and Navantia showcased their advanced AIP integration technology on the S-83 submarine, which is currently under construction for the Spanish Navy. This technology is designed to enable submarines to remain submerged for extended periods, reportedly up to 21 days, significantly enhancing operational effectiveness.

Larsen & Toubro Shipbuilding has assisted in the development and construction of the Arihant-class nuclear-powered ballistic missile submarines, since 2009.

The AIP system being integrated into these submarines utilizes bio-ethanol as a hydrogen source, making it not only efficient but also environmentally friendly. This system is touted as one of the most compact and easy-to-maintain AIP solutions available globally. The use of bio-ethanol mitigates risks associated with hydrogen storage while ensuring widespread availability for refuelling.

Bioethanol is a cost-effective fuel source that is widely available, making it easier to procure and use globally. Its accessibility means submarines can refuel without needing specialized infrastructure, which is crucial for operational flexibility in various maritime environments. The high density of hydrogen produced from bioethanol improves the efficiency of the AIP system. This allows submarines to operate longer underwater, with capabilities extending up to 21 days without surfacing, significantly enhancing their stealth and operational range.

Bioethanol is stored in liquid form, which eliminates the risks associated with storing gaseous hydrogen. This characteristic reduces potential hazards during storage and handling, making the AIP system safer for crew members. As a renewable energy source, bioethanol contributes to lower carbon emissions. The carbon released during combustion is offset by the carbon absorbed during the growth of the feedstocks used to produce the ethanol, making it a more environmentally friendly option compared to traditional fossil fuels.

Operational Independence: The ability to generate hydrogen onboard using bioethanol allows submarines to maintain operational independence from surface support for refuelling. This capability enhances mission duration and reduces vulnerability during operations.

The integration of bioethanol into the AIP system simplifies the fuel cell design, leading to higher reliability and maintainability. This modular approach allows for easier repairs and replacements during missions, increasing overall operational availability.

Valued at over €4.8 billion, this project represents India's largest defence acquisition initiative and is expected to be followed by a 30-year lifecycle support contract of similar value. The collaboration also aligns with India's strategic partnership model for defence procurement, emphasizing indigenous content and technological collaboration.

Beyond submarines, L&T and Navantia are exploring opportunities in other military programs and green energy projects, indicating a broadening of their partnership that could extend into various defence and civilian sectors.