Flocean Prepares to Launch World's First Commercial Subsea Desalination Plant Off Norway's Coast
Norwegian startup Flocean is set to begin commercial operations at its Mongstad subsea desalination facility in 2026, using natural deep-sea pressure to cut energy consumption by up to 50 percent compared to conventional land-based plants.
A New Approach to Freshwater Production
Norwegian startup Flocean is preparing to bring the world’s first commercial-scale subsea desalination plant online at Mongstad, Norway, in 2026. The system, known as Flocean One, operates by submerging reverse osmosis pods approximately 400 to 600 meters below the ocean surface, where natural hydrostatic pressure drives seawater through filtration membranes without the energy-intensive artificial pressurization that conventional desalination plants require.
The technology builds on a year-long demonstration at the company’s Mongstad Industrial Park test site. That earlier installation, called Flocean Zero, has been operating since November 2024 and has processed over five million liters of seawater into drinking water that meets both World Health Organization standards and Norwegian drinking water requirements.
How It Works
Traditional desalination relies on pumping seawater through reverse osmosis membranes at high pressure, a process that consumes significant amounts of electricity. Flocean’s approach eliminates much of that energy demand by positioning its pods at depths where the ocean itself provides the necessary pressure. According to Flocean CEO Alexander Fuglesang, the system is “essentially a subsea pump cleverly coupled to existing membrane and filter technology”. Purified water is then pumped back to shore through subsea pipelines.
Operating at depth also brings secondary advantages. Below 200 meters, minimal sunlight reduces bacteria and organic pollutants, which means the system requires significantly less chemical pretreatment than surface-level plants. The consistent deep-sea temperature and pressure conditions further reduce operational variability.
Capacity and Scaling
Flocean One will initially produce 1,000 cubic meters of fresh water daily. The company says its modular architecture allows scaling to up to 50,000 cubic meters per day, enough to serve a mid-sized city. Each individual pod is designed to produce up to 7,500 cubic meters daily.
The company claims the approach yields 30 to 50 percent lower energy consumption and greenhouse gas emissions compared to traditional land-based desalination, along with a 95 percent reduction in coastal land footprint. The system also avoids discharging concentrated brine near sensitive coastal habitats, a persistent environmental concern with conventional desalination.
Investment and Industry Context
Flocean extended its Series A funding round to $22.5 million in November 2025, adding water technology company Xylem as a strategic investor. The system received external certification from DNV, a global assurance and risk management firm. Flocean was also named one of TIME’s Best Inventions of 2025, the only desalination solution on that year’s list.
Flocean is not alone in pursuing subsea desalination. Netherlands-based Waterise has secured its first industrial customer and is planning a Red Sea facility, while Bay Area startup OceanWell has been testing a prototype near Los Angeles. Both companies use similar principles of leveraging deep-sea pressure, though Flocean is furthest along in reaching commercial deployment.
Challenges Ahead
Industry experts have noted several constraints on the technology’s broader adoption. Subsea desalination requires steep coastal drop-offs close to shore, making it unsuitable for regions with wide continental shelves. The approach also remains more expensive than traditional freshwater sources where those are available, and its long-term impact on marine ecosystems at deployment depth requires further study.
Reaching city-scale deployment could take a decade or more, according to water infrastructure analysts. Nevertheless, Flocean operates on a Build-Own-Operate model and has announced plans for additional projects in the Mediterranean, Red Sea, and Indian Ocean regions, targeting areas where freshwater scarcity is intensifying due to climate change and population growth.