This article was originally published in
Hakai Magazine
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In May 2022, California officials unanimously rejected a plan to construct a $1.4 billion desalination plant in Huntington Beach. They argued that the plant would yield expensive water and potentially harm the marine environment. While this decision did not categorically dismiss all forms of desalination, it did highlight some of the challenges that have rendered desalination an impractical solution for California’s water problems.
According to Dragan Tutic, the CEO of Oneka Technologies, large desalination plants reliant on fossil fuels are not the sole means of extracting fresh water from the ocean. His company is preparing to introduce a sustainable and practical desalination system in the small city of Fort Bragg, located on California’s North Coast.
Once a lumber town until the closure of the Georgia-Pacific mill in 2002, Fort Bragg has now become a popular tourist destination, boasting unspoiled beaches nestled amidst rocky cliffs, vibrant tide pools, and a renowned sea glass beach.
Water scarcity is a pressing issue in Fort Bragg, much like the rest of California. The city relies on only three surface-water sources: the Noyo River and two tributaries. During dry periods, all three sources can dwindle, and the Noyo River can become brackish, putting the city at risk of water shortages.
John Smith, Fort Bragg’s director of public works, remarks, “We’re facing a dilemma, which is why we’re turning to the ocean as a potential solution.”
Desalination has recurrently emerged as a solution in the Golden State, grappling with issues like overdrawn groundwater and shrinking reservoirs. On the surface, it appears to be a simple process—extract the salt from the abundant seawater offshore. However, conventional desalination plants are large, costly to operate, and can have adverse environmental impacts, especially when powered by fossil fuels. For instance, the original plans for the Carlsbad desalination plant in Southern California required over 200,000 megawatt hours of electricity annually, equivalent to the consumption of approximately 20,000 households.
Oneka’s experimental water-desalination device diverges from California’s conventional desalination plants. It takes the form of a buoy just a few meters wide. The device’s compact size is advantageous, but its main innovation lies in its reliance on ocean power. As the buoy oscillates with the waves, it draws water through a filter and a reverse-osmosis membrane, effectively removing salts and other minuscule particles. John Smith describes it as “surprisingly simple.”
Andrea Achilli, a chemical and environmental engineer at the University of Arizona with no affiliation to Oneka, refers to devices of this nature as “direct-desalination systems.” Direct desalination can also be achieved using solar energy, which can be converted into heat for thermal desalination. In simple terms, thermal desalination involves boiling salt water, collecting the vapor, and leaving the salt behind. Similarly, the Oneka buoy harnesses energy from the waves itself, requiring no external power source. Achilli comments, “It’s an excellent utilization of wave energy.”
The buoys manufactured by Oneka circumvent the environmental issues associated with more established desalination techniques. Traditional desalination generates brine—a highly concentrated, salty sludge that necessitates careful disposal. However, the brine released by Oneka’s buoy is low in concentration, allowing it to be safely discharged back into the ocean without significant environmental consequences, according to Tutic.
Oneka has already deployed this technology off the coasts of Florida and Chile, modifying the design based on encountered challenges. Tutic reveals that one major obstacle has been ensuring the buoy’s durability against storms. He explains, “When we first deployed our initial version in 2015 and 2016, most of them broke in the ocean. But through those experiences, we learned and improved.” Tutic asserts that the latest iteration can withstand waves up to six meters high and can be easily disconnected and relocated in anticipation of severe weather conditions.
Initially, the Fort Bragg installation will include one device capable of producing up to 50,000 liters of fresh water per day. While this quantity may seem insignificant, Tutic explains that the pilot device aims to collect data on water quality and system performance, which will subsequently guide refinements and adaptations. Eventually, Oneka envisions an array of devices deployed in the area. Tutic states, “The system is modular, so you can adjust the number of units as needed to produce the desired volume of water.”
However, Achilli remains somewhat skeptical. He asserts, “The energy potential of wave energy is immense due to the vastness of the ocean.” However, he cautions that renewables are less concentrated forms of energy, necessitating a significant amount of materials and resources to fully harness their potential. In other words, numerous buoys would be required.
As Fort Bragg grapples with its water challenges, Smith emphasizes that desalination is just one component of the city’s comprehensive strategy. They have also implemented a mobile desalination plant to treat brackish water from the Noyo River and have plans for constructing reservoirs.
Smith believes that the Oneka buoys do not offer a complete solution but considers the pilot project more than just a means to address Fort Bragg’s water needs. It serves as a proof of concept, demonstrating how technology and engineering can play a role in overcoming California’s persistent water issues. Smith asserts, “I view this as an excellent starting point.”
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