Ulsan launches development of hydrogen fuel cells for submarines to lead global market

Ulsan has launched an effort to domestically develop hydrogen fuel cell technology for submarines, drawing on what the city describes as the country's most advanced hydrogen industry ecosystem — spanning production, storage, transport and utilization. The initiative is expected to significantly improve the performance of submarines and unmanned underwater vehicles (UUV), including their ability to sustain prolonged dives.

The city announced Wednesday it had been selected for a new research and development project under the Ministry of Climate, Environment and Energy's 2026 energy technology development program. The project focuses on developing a 20-kilowatt submarine fuel cell system based on a nitrogen-circulation mixed-gas approach using commercial fuel cell stacks.

Ulsan has since signed a national R&D agreement with six participating institutions, including HD Korea Shipbuilding and Ulsan Technopark, and has begun research and development work.

The project is led by the K-Fuel Cell consortium, which aims to advance the pure-oxygen air-independent propulsion (AIP) technology currently used in submarines. The consortium will develop an integrated gas supply, circulation and control system capable of stable operation in a mixed nitrogen-oxygen environment. Low noise and extended dive endurance are central to the technology.

The goal is to broaden the options available beyond conventional pure-oxygen AIP systems and deliver next-generation, high-reliability submarine propulsion technology with improved efficiency and safety tailored to specific operational requirements.

The project runs from this year through 2029 — 45 months in total — with funding of 11.33 billion won ($7.37 million) from government and other sources. Participating institutions include K-Fuel Cell as the lead agency, along with Ulsan, Ulsan Technopark, Soongsil University's Industry-Academic Cooperation Foundation and Hongsworks. HD Korea Shipbuilding joins as the end-user company that will apply the final technology, strengthening the path to commercialization and demonstration.

The core of the project is developing a 20-kilowatt nitrogen-circulation fuel cell system for submarines. The system will blend 20 percent oxygen as the oxidant and 80 percent nitrogen as the diluent — an environment similar to ordinary air — and integrate operation, control, thermal and water management technology. It must also function reliably under the incline and vibration conditions submarines experience.

Once the technology is complete, it is expected to address the high-risk, high-cost structure of existing pure-oxygen AIP systems and reduce maintenance, repair and overhaul costs by replacing foreign-made components with domestic alternatives.

The technology could also be extended beyond crewed submarines to next-generation unmanned underwater vehicles and other UUV platforms, potentially securing a share of the eco-friendly marine propulsion market.

"We plan to combine the hydrogen fuel cell demonstration center and hydrogen mobility technology already in place with HD Korea Shipbuilding's submarine construction expertise to build a world-class marine-specialized fuel cell ecosystem and develop Ulsan into a global hub for marine energy technology," a city official said.