Spanish shipbuilder Navantia has completed testing of the air-independent propulsion (AIP) system integrated into the S-83 Cosme García submarine, the third boat in Spain’s S-80 series.
The testing campaign began in June at Navantia’s Cartagena shipyard, where the AIP system was installed in a 12-meter-long, approximately 400-ton section of the submarine before the section is joined to the rest of the pressure hull.
The tests demonstrated the system’s integration, performance and operational capabilities under conditions designed to represent actual submarine operations. The dedicated test facility can simulate factors including diving depth and forward speed, allowing Navantia to demonstrate power generation for battery charging while submerged.
The AIP system, known as BEST (Bio-Ethanol Stealth Technology), is a third-generation system that produces hydrogen onboard from bioethanol rather than storing hydrogen. The hydrogen is then used with oxygen in a fuel cell to generate electricity.
The company said the system will allow S-80 submarines to remain submerged for up to three weeks, compared with the shorter underwater endurance of conventional diesel-electric submarines that rely solely on batteries and periodically need to snorkel to recharge them.
The S-80 program covers four conventional submarines for the Spanish Navy. The lead boat, S-81 Isaac Peral, entered service in 2023, while S-82 Narciso Monturiol is undergoing trials. S-83 Cosme García and S-84 Mateo García de los Reyes remain under construction at Cartagena.
The S-80 submarines are approximately 80 meters long, have a submerged displacement of around 3,000 tons and can operate with a crew of 32 sailors, plus accommodation for additional personnel. The class features an integrated combat system developed by Navantia Sistemas in collaboration with Lockheed Martin.
The AIP system is being introduced as a serial capability beginning with S-83. The first two boats, S-81 and S-82, were designed to allow the technology to be incorporated during their first major overhaul.
“All of this consolidates the technological maturity of the system and demonstrates the capacity of Spanish industry to innovate and undertake complex technological developments. I would like to congratulate everyone who has contributed to this development, demonstrating our commitment to Spain’s defense capabilities and to an innovative approach that advances our strategic autonomy and technological sovereignty,” said Navantia President Ricardo Domínguez García-Baquero.