Lower-Energy Desalination Technology Could Expand Water Security Options for Drought-Prone Regions

A new approach to desalination is moving from pilot testing toward a potential offshore deployment in California, raising hopes that seawater could become a more practical and lower-energy source of drinking water for drought-prone communities.

According to Forbes, OceanWell is developing a subsea desalination system designed to use about 40% less energy than conventional desalination. The company’s concept relies on deep-ocean pressure to help drive reverse osmosis, the membrane-based process used in most modern desalination plants. Instead of pulling large volumes of seawater into an onshore facility and pressurizing it with energy-intensive pumps, OceanWell plans to place modular filtration pods underwater, where natural hydrostatic pressure can support the separation of fresh water from saltwater.

The technology is being watched closely by water agencies in Southern California, where prolonged drought, shrinking imported water supplies and climate volatility have increased interest in new local sources of water. OceanWell has been working with Las Virgenes Municipal Water District, which serves communities including Calabasas and surrounding areas in Los Angeles County. The district was severely affected by state water supply cuts in 2022, exposing the risks of dependence on imported water.

Pilot Results Point to Lower Energy Use

The first major test has taken place not in the ocean, but in Las Virgenes Reservoir. This allowed the company and the district to study the system in a biologically active water environment before attempting offshore deployment. According to Las Virgenes Municipal Water District, the reservoir pilot ran for more than three months, produced more than 150,000 gallons of water, and achieved 93% uptime. The district also reported that the pilot water quality exceeded drinking water requirements and that the system showed the potential to use 40% less energy than traditional desalination.

The next step is more difficult. OceanWell’s commercial vision involves installing an array of pods several miles off the coast of Malibu, at depths of roughly 400 metres. The company calls this model a “water farm.” In this configuration, the system would produce fresh water offshore and send it to land through a pipeline for treatment, storage and distribution.

Recent reporting on the proposed California project indicates that a full-scale deployment could involve dozens of subsea units, with a possible capacity of around 60 million gallons per day. That would make it a significant new water source if the system proves technically, economically and environmentally viable. However, a commercial project would require extensive permitting, environmental review, financing and long-term operating data.

Why Energy Matters in Desalination

Desalination is already a critical water source in many arid coastal regions, islands and industrial hubs. It is particularly important in the Middle East and North Africa, where large-scale plants supply municipal, industrial and agricultural demand. But its expansion is constrained by energy use, cost and environmental concerns.

The International Energy Agency has noted that desalination is becoming more electricity-driven as reverse osmosis replaces older thermal processes. Modern seawater reverse osmosis typically requires electricity for intake, pumping, membrane treatment, brine handling and controls. While it is generally less energy-intensive than thermal desalination, it can still add significant load to power systems, particularly in regions that rely heavily on desalinated water.

The IEA estimates that desalination could become a growing source of electricity demand as water stress intensifies and countries turn to secure, climate-resilient water supplies. This makes energy efficiency central to the climate case for desalination. A lower-energy process could reduce operating costs and make desalination easier to pair with renewable electricity, but it would not eliminate the need to manage grid impacts.

Environmental Questions Remain

Desalination projects often face scrutiny because of two main environmental issues: marine intake impacts and brine discharge. Conventional coastal plants draw seawater into large onshore facilities, which can harm marine organisms if intake systems are poorly designed. They also discharge concentrated brine back into the ocean, which can affect local ecosystems if not properly diluted and dispersed.

OceanWell argues that its subsea approach could reduce both problems. The company says its intake system is designed to protect marine life and that brine can be dispersed more gradually in deep ocean currents. Las Virgenes reported preliminary findings suggesting that the pilot intake design protected aquatic life in the reservoir setting. Still, regulators will need ocean-specific data before approving a full project.

The offshore model may also reduce the need for large coastal facilities, which could be important in densely developed or environmentally sensitive coastal areas. However, subsea infrastructure brings other considerations, including seabed disturbance, pipeline routing, maintenance access, storm resilience and potential impacts on marine habitats.

Implications for Water Utilities and Net-Zero Planning

For water utilities, the OceanWell project highlights a broader shift in water infrastructure planning. Climate adaptation is no longer limited to conservation and reservoirs. Utilities are increasingly assessing portfolios that combine demand management, water recycling, groundwater storage, stormwater capture, leakage reduction and, in some cases, desalination.

Lower-energy desalination could become valuable where local freshwater supplies are unreliable and where imported water is exposed to drought, political constraints or ecological limits. It may also interest industrial users that need high-purity water, including semiconductor manufacturing, power generation, hydrogen production and some clean technology supply chains.

For net-zero strategies, the key question is not whether desalination can provide water, but whether it can do so with acceptable energy use, emissions and ecological impacts. A desalination plant powered by fossil-heavy electricity can increase emissions. A highly efficient system connected to clean power could offer a more resilient option, especially where water shortages threaten communities, agriculture or industry.

The OceanWell pilot does not yet prove that deep-sea desalination can be deployed widely or cheaply. It does show that companies and water agencies are testing alternatives to conventional onshore plants at a time when water scarcity is becoming a core climate risk. The next stage will determine whether lower-energy subsea desalination can move from promising pilot results to bankable infrastructure.

Source: www.forbes.com