Navantia’s shipyard in Cartagena has begun the first air-independent propulsion (AIP) system installation on a Spanish Navy S-80 Plus-class diesel-electric submarine, the company announced on 31 October 2024.
The first boat to receive an AIP system, which offers extended underwater endurance, will be Cosme Garcia (S-83): the third of four submarines in the class. First-in-class Isaac Peral (S-81), which was commissioned on 30 November 2023, and second-in-class Narciso Monturiol, which is still building, did not initially receive an AIP system, which will be retrofitted during their first major overhauls.
The S-80 Plus class’ AIP system generates hydrogen from an alcohol produced sustainably (bioethanol) and stored on board the submarine using a bioethanol processing system. This hydrogen, combined with oxygen also stored on board, generates electricity through a fuel cell capable of charging the submarine’s batteries and keeping it submerged two to three times longer than a conventional diesel-electric-powered submarine.
“This AIP system is capable of operating at any depth and in all operational conditions, allowing it to adapt to any navy mission and making it the most advanced AIP system on the market,” Navantia asserted, adding that the S-80 Plus class “are the only 3,000-tonne [submerged displacement] submarines in the world equipped with this system”.
Installation of the first AIP system in an S-80 Plus-class submarine is a welcome milestone for a programme that is substantially behind schedule. Construction of the four boats was authorised in 2003, with deliveries originally expected to begin around 2015, but excessive weight issues and a consequently required redesign caused significant delays. The redesigned class is now larger than when first conceived, with a length of 81 m instead of 71 m and a 3,000-tonne submerged displacement instead of 2,465 tonnes.
The S-80 Plus class, which can accommodate a crew of 32 plus eight additional personnel, has a surface speed of 10 kts, a submerged speed of 19 kts and an endurance of 50 days. The submarines are armed with six 21-inch (533 mm) bow torpedo tubes and can carry heavyweight torpedoes, mines and Harpoon anti-ship missiles.
Navantia is hoping to see significant export interest in the S-80 Plus class once more Spanish Navy boats become operational.
