Desalination Solutions: Turning Ocean Water Into Freshwater for a Sustainable Future
- Jane Marsh
- 2 hours ago
- 6 min read
Jane Marsh
Imagine running out of water on a hot summer day on the beach.. Staring out at the vast sea might whet your palate, but you know it isn’t safe to drink. It’s ironic to live on a “blue planet” while facing a shortage of potable water. Droughts are drying up streams, leaving entire populations thirsty.
Desalination is an emerging solution to this rising crisis — a process that turns salty ocean water into fresh, drinkable water. Although the technology is still in its infancy, it looks promising for a sustainable, water-secure future.
The Global Water Crisis
A recent report from the United Nations University Institute for Water says that 2.2 billion people lack access to safe drinking water, while 4 billion experience severe water insecurity for at least one month each year. Another 3.5 billion people endure poorly managed sanitation, putting them at risk of severe waterborne illnesses.
A growing population and limited access to freshwater resources compound this. Although freshwater accounts for 3% of the planet’s water, only 0.6% is available and safe for drinking. The rest remains locked up in ice caps and glaciers, or is too polluted for human consumption.
The ocean, however, spans 71% of the Earth’s surface and contains over 1.3 billion cubic kilometers of water. Despite this surplus, seawater’s salinity is too high for people to ingest.
Although the cells in your body depend on sodium chloride to maintain the proper chemical balance, an excess could be fatal — your kidneys can only produce urine with a lower salinity than saltwater. To eliminate the excess salt you’d drink in ocean water, you would have to urinate more than you consume.
This conundrum has left scientists puzzled for decades as the water crisis worsens with climate change, population growth and pollution. Fortunately, the rise of desalination and water recycling could positively change the outcome.
What Is Desalination?
Desalination converts various water sources into potable water, including seawater, treated wastewater, brackish water and agricultural runoff. The two primary methods apply thermal or membrane-based technologies.
Thermal desalination involves heating water into steam, leaving behind salts when it condenses back into a liquid. Although the technique is highly effective at achieving excellent purification, it’s extremely energy-intensive.
Membrane-based desalination, also known as reverse osmosis, is a more common form of purification. It applies high pressure to force water through a fine, salt-blocking membrane. The solution isn’t perfect, though, as high salt concentrations can damage the material. The optimal choice depends on the salt content and required purity.
Startups Making a Splash
Innovative startups are seeking to boost seawater desalination to address water shortages worldwide. Water technology company OceanWell is launching the first U.S. subsea desalination project off the coast of California, projected to produce 60 million gallons of freshwater daily.
Engineers will submerge about 60 of its modular pods on the ocean floor at depths of 1,300 feet, where natural deep-sea pressure will power reverse osmosis. The solution has proven effective in trials, reducing energy consumption by 40% compared to traditional plants and avoiding disruption to marine life. In addition to salt, the fine membranes can block microplastics, bacteria, viruses, and per- and polyfluoroalkyl substances.
Norwegian startup Flocean is also making waves with an energy-efficient subsea desalination system. The company is placing pods 400 to 600 meters deep on the seafloor — about 1,300 to 1,900 feet — with the intent of producing enough freshwater for 37,500 people.
The True Cost of a Glass of Seawater
Desalination offers ample opportunities to address water scarcity, but there are barriers to its widespread adoption. It leaves many questions regarding the financial and ecological consequences of implementing these solutions.
Financial Implications
The initial investment in large-scale desalination plants is high, while reverse osmosis processes require substantial energy to pump water through membranes. Ongoing maintenance, filter replacements, and compliance with environmental regulations also entail various expenses and fines. It could cost between $800 to $1,400 to desalinate 325,000 gallons of seawater without the additional outlays.
Ecological Implications
Although desalination is crucial for providing potable water to arid, drought-stricken regions, the process leaves behind a salty waste product called brine. According to one study, global brine production exceeds 140 million cubic meters per day and is likely to rise as water scarcity increases.
Brine poses significant environmental hazards, particularly because its disposal causes ocean acidification and harms marine life. Because of this, there have been calls to mitigate the impacts by repurposing brine using new technologies.
How Does Water Recycling Differ From Desalination?
Although some might refer to desalination as recycling seawater by removing high salt concentrations, that’s the extent to which it produces potable water. Water recycling treats municipal wastewater, industrial water and greywater for reuse and is generally more energy-efficient.
Recycling often utilizes biological treatments and advanced filtration to remove harmful contaminants. The water is then suitable for irrigation, industrial use and, in some cases, human consumption.
The U.S. Environmental Protection Agency says more than 500 facilities nationwide recycle water to meet community needs. Common applications include ensuring enough supply during prolonged droughts, protecting streams and rivers, preventing saltwater intrusion in groundwater supplies and cooling data centers.
Like desalination, water recycling faces high infrastructure costs and regulatory hurdles to work properly. Advanced treatments for safe contaminant removal are costly. There is also public resistance to this approach to achieving potable water, as the idea of drinking treated wastewater turns many people off.
Water Recycling Projects Across the U.S.
The WaterReuse Association highlights several projects with established water recovery systems. For example, the East Bay Municipal Utility District in California is among the nation’s largest industrial reuse projects. This one facility supplies about 7.5 million gallons of recycled water to Chevron’s Richmond refinery every day.
Tampa Electric in Florida is another enterprise that has recycled water from local municipalities to cool its power station since 2015. It diverts 7 million gallons of water from being discharged into the environment daily for plant operations.
Additionally, Frito-Lay has implemented on-site water recovery at its Arizona plant — a first-of-its-kind for the food industry. The system recycles up to 75% of the factory’s water to drinking-water quality, enabling it to reuse it in its operations safely. The solution saves the company 100 million gallons of water annually.
Advances in Desalination and Water Recycling Solutions
Developments in desalination are addressing high energy consumption and brine waste. For instance, a conventional thermal desalination plant consumes over 200 megajoules of energy — about 55.6 kilowatt-hours of electricity — and emits over 10 kilograms of carbon dioxide (CO2) per cubic meter of water produced. At this rate, it could create over 400 million tons of CO2 annually by 2050.
One solution is integrating desalination with concentrated solar power (CSP). CSP plants convert only 30% to 47% of solar energy into electricity, meaning waste heat can be repurposed for desalination, saving over 50% of energy.
Additionally, advanced brine management is turning the waste product into a valuable resource, utilizing it for CO2 sequestration, emissions capture and the creation of useful minerals, such as sodium bicarbonate.
The process, known as brine mining, employs artificial intelligence for greater plant efficiency, while biomimetic membranes are inspired by nature and offer more promising separation of salts and minerals. Hybrid systems also combine several extraction methods to maximize resource recovery and boost circularity.
The Next Wave in Water Security
Whenever you find yourself thirsty and staring out at the sea, know that solutions are underway to expand the conversion of seawater to drinking water. As desalination and water recycling technology advances, dire shortages could very well become a thing of the past.
Citations
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