World’s first subsea desalination facility will start making clean water in 2026

Turning seawater into potable water is so expensive and energy-intensive that it's impractical in most parts of the world, but a Norwegian company is testing a new approach that could change that. Floquean will launch the world's first commercial-scale underwater desalination plant in 2026 and says its system will significantly reduce the cost and energy consumption of the process.

Global water demand is growing, fueled by population growth, climate change and industrial uses such as data centers and manufacturing. Meanwhile, fresh water becomes less abundant due to drought, deforestation and over-irrigation.

Ground-based desalination currently produces about 1 percent the world's freshwater reserves, with more than 300 million people relying on this source to meet their daily water needs. Largest plants – in the Middle Eastwhere cheap energy makes the technology more feasible and water scarcity makes it more necessary.

The leading desalination technology today is reverse osmosis. This method pumps seawater through a membrane with microscopic holes that allow only water molecules to pass through, while salt and other impurities are filtered out. The water must be under pressure to force it through the filters, a process that requires enormous amounts of energy.

Flocean's approach is to plunge water-filtering capsules deep into the ocean, separate seawater from salt at depth, and then pump the fresh water back to land. By placing reverse osmosis capsules deep underwater, the technology uses hydrostatic pressure—the weight of all the water pressing down from above—to force seawater through filter membranes.

According to the company, less pumping means less energy consumption, about 40 to 50 percent less than traditional desalination plants. In addition, sea water becomes cleaner as you go below sea level. sunlight zone (which extends up to 200 meters below the water's surface), meaning the water does not require as much pre-treatment before it reaches the membranes.

“Basically, it’s pretty boring there from a technological and engineering point of view,” says Alexander BirdsongFounder and CEO of Flocean. “It's the same salinity, temperature, pressure. It's dark. There's not a lot of bacteria that can cause biofouling.” The same hydrostatic pressure that pushes water through the membranes also helps disperse the salty brine byproduct, which Floquean says contains no chemicals that could harm marine life.

Over the past year, Flocean has desalinated water at a depth of 524 meters at its test site in Norway's largest offshore supply base, the Mongstad Industrial Park. Its commercial venture, called Flocean One, is being built at the same location and will initially produce 1,000 cubic meters of fresh water per day when it launches next year. The operation can then be expanded in a modular manner by adding additional desalination modules.

“Our philosophy is to keep the subsea installations the same and scale them up by getting bigger rather than by building bigger and bigger machines,” says Fuglesang. However, scaling will require engineering trade-offs at the system level. Because more modules will share the same power supply and controls, Flocean engineers need to design the power distribution and permeate collector—the mechanism that directs purified water from multiple membranes into a single output line—so that scaling is as simple as possible.

“This solution could be viable in suitable locations, providing accessible water while reducing costs, but it remains to be proven on a large scale,” says Nidal Hilal at New York University Abu Dhabi. “Wide municipal deployment is likely dependent on overcoming technical and economic challenges over several years.”

Reducing costs will be critical to further scaling up the technology, says Hilal, as it is still much more expensive than obtaining fresh water through traditional methods such as abstraction from lakes or aquifers.

Cleaning and maintaining membranes will be one of Flocean's biggest costs. Advances in membrane technology will help; Hilal's research group is working on electrically conductive membranes that use electricity to repel salt ions and contaminants, maintaining their purity and increasing performance. Researchers are also exploring ways to recycle single-use plastics into membrane materials, improving sustainability while reducing costs. “Stronger membranes and highly efficient pumps can further reduce operating costs, and the integration of renewable energy sources reduces energy costs,” says Hilal.

Flocean One is due to begin producing fresh water in the second quarter of 2026. If the technology works as planned, it could help Flocean gain support to build larger plants elsewhere. “The biggest challenge for us is getting perfect alignment,” says Fuglesang. “We need the customer, we need government approvals and we need strong financial partners.”