Ocean water to fresh: First-of-its-kind wave-powered pilot project in Fort Bragg set to test

Fort Bragg is embarking on an innovative pilot project to desalt ocean water for the Mendocino Coast community using carbon-free wave action to power an energy-intensive process that in other cases generates climate changing greenhouse gases.

The design comes from a young Quebec-based company called Oneka Technologies that makes floating, raft-like units containing the equipment needed to draw in water, pressurize and force it through reverse-osmosis membranes, then send it back to shore in a flexible pipe on the ocean floor.

Fort Bragg will start with a single, 16-foot by 26-foot unit, anchored about a mile off shore of the Noyo Headlands, Public Works Director John Smith said.

It could be deployed in perhaps six or eight months, once a variety of tests are completed to determine the best location for it. Permits also must be acquired to ensure the project complies with California Ocean Plan water quality provisions for desalination facilities and meets other regulatory requirements.

The project is to be covered by a $1.5 million state grant through the Department of Water Resources, which includes permitting and regulatory expenses, Smith said. The grant was announced last month in a new round of funding totaling $5 million for three desalination efforts under the state’s strategic plan to expand water supplies, increase storage capacity and generally improve drought resilience.

Assuming it’s successful, Fort Bragg’s desalination unit could provide a replicable model for coastal communities around the North Coast and on other U.S. coastlines, as well, water officials said.

The equipment also is modular by design and can be scaled up using an array of floating units spaced apart in the ocean.

“It’s a very small version of what it could be in the future,” Smith said. “It’s pretty fantastic.”

Very fine mesh across the unit’s water intake is designed to prevent aquatic wildlife from getting sucked in and being harmed. The vertical line to the anchor and any surface lines connecting floating rafts to each other are under high tension and very taut, so they aren’t subject to entanglement, Oneka co-founder the Chief Executive Officer Dragan Tutic told The Press Democrat.

Using wave energy to mechanically pressurize the water means the process doesn’t contribute to the atmospheric changes that are contributing to water scarcity in the first place. There is no electricity, no connection to the grid, no chemical use.

And only 25% of a given batch of ocean water is treated. The resulting concentrated brine is then diluted by the remaining 75% of the batch before it’s discharged back to the ocean. That water will be about 30% more saline than the existing ocean water, addressing another typical concern with desalination. Sensors on the rafts monitor the salinity of the incoming and outgoing water, he said, but the discharged water dilutes so quickly in the ocean, it’s difficult to measure any increased salinity around the raft.

“It’s an amazing and innovative project,” Fort Bragg Mayor Bernie Norvell said. “It addresses both of the main obstacles to desal: the amount of energy needed to produce the desalinated water and what to do with the salt. The energy is produced by the wave action, and the salt is filtered and returned directly to the ocean. Win, win.

“We hope it is highly successful, and we end up with several more,” Norvell said.

Water scarcity is a growing concern around the globe, as rising temperatures cause increased evaporation and more extreme swings between drought and severe storms and flooding.

During California’s recent, three-year drought, the Mendocino Coast faced particular challenges, given its dependence on shallow groundwater wells, which began running dry. Many communities and individual residents elsewhere on the coast turned to Fort Bragg to purchase water.

But they eventually were cut off, as the city, its surface water sources running low, struggled to meet the needs of its own 7,000-plus residents.

The water shortage was so severe in towns like Mendocino that the County of Mendocino and the state Department of Water Resources arranged to purchase water from the city of Ukiah and truck it over the hill to the coast in late summer of 2021 to supply minimal needs there.

Fort Bragg, meanwhile, obtained emergency state funding for a mobile desalination unit set up that same fall to remove the salt from brackish water at an intake in the Noyo River 4½ miles upstream from Noyo Harbor.

The river was running at such a low ebb that tidewaters pushing upstream had made the water there unusable. But the city could only rely on about half the mobile unit’s capacity because of limits on how much dense brine it was authorized to dispose of through its waste water treatment facility.

Oneka, launched in 2015, heard about Fort Bragg’s foray into the world of desalination through mutual connections approached the city about a pilot project using its wave technology.

Though relatively new to the marketplace, with units so far deployed off the coasts of Chile and Florida, Oneka last year won the U.S. Department of Energy’s “Waves to Water Prize,” beating 66 initial entrants with technologies using the power of waves to turn ocean water into drinking water.

The company currently has three unit sizes, including a small, nimble product that can be deployed quickly to provide emergency water supplies for communities hit by natural disasters. It is working on a new larger unit twice the size of the one Fort Bragg is getting but with four times the production capacity, supported by the Canadian government, Oneka co-founder Tutic said.

The Fort Bragg project provides his company with a demonstration site on the California Coast with the opportunity to glean information about its technology’s performance in northern Pacific waters, though the coastal land is similar to Chile, he said.

It also aligns with Fort Bragg’s Blue Economy Initiative, which provides direction for the city’s cultivation of emerging, ocean-related industries like aquaculture, renewable energy and mitigation banking that contribute to a healthy ocean while ensuring existing fishing, recreation and other long-standing economic activities maintain the ocean’s long-term health.

“This is just one more way our community is trying to stay ahead of the curve,” Norvell said. “Do not be afraid to be innovative and just get started.”

California has seven active seawater desalination facilities. An eighth has been approved but is not yet operating. All are on coastal land, mostly in central or southern California, said Laura McLellan, senior environmental scientist with the State Water Resources Control Board’s Recycled Water and Desalination Unit.

The state is also supporting desalination facilities to treat brackish groundwater as part of a major, ongoing push to diversify water supplies to meet current and future needs.

But this is the first time its been asked to fund offshore, wave-powered technology like Oneka’s, McLellan said.

“It is very unique for California, is my understanding,” said Matt Herman, a water resource control engineer with the North Coast Regional Water Quality Control Board. “I think the hope of the corporation that does these offshore desalination units is to make them more common, and in this case, it might actually be a good fit for the North Coast communities because it’s very scalable”

“I’m an engineer,” Herman said. “I find it intriguing … I want to see what the study turns out … whether it’s effective in our region. Time will tell.”

You can reach Staff Writer Mary Callahan (she/her) at 707-521-5249 or mary.callahan@pressdemocrat.com. On Twitter @MaryCallahanB.