As global water scarcity spreads and more regions begin to run out of the freshwater they need for daily life, desalination is heralded as the answer. It already provides countless people with reliable clean water, but it also carries some disadvantages as an energy-intensive process with high environmental costs.
Now, OceanWell’s new offshore desalination system promises to overcome these downsides and offer another option. In this article, we explore the new technology and find out what makes it different.
The Birth of OceanWell
The OceanWell concept began over seven years ago after Robert Bergstrom started exploring new desalination processes to provide drinking water cost-efficiently and with fewer environmental impacts. The concept was a natural culmination of the technologies he developed throughout his career to provide clean and fresh water to people in water-stressed communities.
Previously, Robert founded Seven Seas Water, a company that produced drinking water for communities and commercial users across the Caribbean, halving the cost of desalinated water. After selling Seven Seas Water, Robert moved to California and explored a new desalination process.
In 2019, alongside Charlie McGarraugh and Dr Michael Porter, Robert set up OceanWell as an entity and after a successful prototype test at a US Naval Base in 2020, the next stage of development began.
Water Scarcity: A Growing Problem
OceanWell points out that water scarcity is a growing problem worldwide with over a quarter of the global population facing extreme water stress. This is expected to grow significantly leading to 2050, as water use continues to increase at a faster rate to population growth. The problem is driven by combination of factors including population growth, economic development, and climate change. These put additional pressure on renewable water sources and further restrict access to clean and reliable water sources. As OceanWell notes:
“We are experiencing more severe droughts, floods, wildfires, and extreme weather events, driving the urgency for more effective management of our water resources. We view the addition of a reliable, sustainable base load supply that eases our dependence on rapidly depleting aquifers as a vital component to the mix.”
Desalination has long been seen as a way to solve some of the issues with global water shortages, but this technology has some core disadvantages which means it is not always suitable.
The Advantages and Disadvantages of Desalination
Desalination is a long-standing technology that certainly provides clean freshwater in various parts of the world. 97% of earth’s water is in the oceans, so desalination is key to to unlocking this vast resource, providing local communities with sources of fresh water even during the worst droughts. Just as importantly, the desalination process removes most impurities, including PFAS, delivering high quality water. It can help regions diversify their water resources and reduce the pressure on aquifers and groundwater wells, providing additional resilience if rainfall patterns or snowmelt change.
However, although it is often mooted as a wonder technology that can solve the scarcity problem, traditional desalination processes carry a number of limitations. One major concern is the high energy demands that create emissions and cost a lot of money even with energy recovery processes. Even if plants use renewable resources, this diverts energy that could be used elsewhere.
Another pressing problem is the environmental damage to local ecosystems because conventional plants pull water from the top of the water column. Here, marine life is at its most abundant and, inside the system, the filters, chemicals, and pressure from reverse osmosis kill 100% of the organisms it entrains. The desalination process also produces concentrated brine that is usually pumped back into the ocean or sent through high pressure diffusers that can damage organisms in large areas of the disposal site.
Finally, desalination plants require large industrial facilities located on coasts, taking up real estate needed for other uses, such as tourism, and restricting the access of local communities to the sea. This is where OceanWell’s technology comes in, which was designed from the ground up as a way to overcome all of the core disadvantages of conventional desalination without losing the benefits.
Moving Desalination Offshore: A New Approach
Recognising that energy is one of the most important limiting factors, OceanWell’s next generation in desalination technology combines reverse osmosis with offshore renewable energy technology. Moving the process into the deeper ocean opens up the new possibility of using natural pressure. Not only does this reduce the energy requirements and lower costs significantly, but the process prevents damage to the oceans.
The technology uses the weight and pressure of the ocean to drive reverse osmosis rather than using energy-intensive pumps. Each project, called ‘water farms’ will consist of multiple desalination pods, which are 40ft/13m cylindrical cartridges containing intake pumps that draw the seawater through a semi-permeable membrane. Once filtered, the system transports the fresh water to land through a pipeline while discharging a low salinity outfall into ocean currents via a riser.
“OceanWell is a passive system that circulates seawater past membranes in a natural high-pressure environment, automatically producing fresh water. We simply harvest the cold fresh water and bring it to shore.
The system operates 400 metres deep in an area of the ocean known as the aphotic zone where less than 1% of sunlight penetrates. Accordingly, the source water used contains much less marine life than the first 200 meters of depth, known as the photic zone.
“Our system has been designed to set a new environmental benchmark for desalination by using natural pressures in the stratum of the ocean with less marine life.”
The pods feature an intake system called LifeSafeTM, which they intend to validate in the coming year. It is designed to protect any marine organisms that encounter the technology.
The Benefits of OceanWell Desalination
By using natural pressure, which is infinite, OceanWell’s systems can operate at a very low recovery rate of 10-15% as opposed to the 50% for conventional desalination processes. Accordingly, the process produces far less highly-concentrated brine and returns the by-product above the ocean floor where it dissipates quickly, returning to ambient salinity within seconds of discharge.
With the new process, OceanWell provides a reliable source of high-quality freshwater without the negative effects on the environment. It is far more energy efficient, costs less than onshore desalination and raises cold water from the depths, providing billions of BTUs of cooling capacity. Another bonus is that the OceanWell technology is highly scalable and far quicker to deploy than building a standard desalination plant.
Finally, because most of the equipment is in the deep sea and offshore, OceanWell does not need large industrial facilities on the shoreline.
Overall, OceanWell’s desalination system will benefit cities, communities, and industries across the world, helping entire regions cope with water stress. As OceanWell points out:
“We aim to reduce the cost of desalinated water with large-scale desalination driven by ocean pressure. Throughout the world, both rural and urban, lives and livelihoods are being lost due to lack of water and our mission is to change that with a new approach to harvesting water from the sea. We exist to help all life forms to survive in a world with growing clean water concerns.”
Overcoming Challenges and the Future of Desalination
There are still some challenges to overcome, especially considering the sometimes-slow rate of change in the water industry, but with pilot programs underway and growing support, the technology is gaining traction:
“We are looking forward to revolutionizing the global desalination industry with affordable and environmentally focused technology. Our next milestone will be the completion of our piloting program with the Las Virgenes district”
“After which we will be ready to build and install the first demonstration system in the ocean, producing 4,000 m3 per day, before scaling up to a commercial water farm (more than 30,000m3 per day).”
With these pilot studies complete, OceanWell intends to push the boundaries of desalination and make the process cleaner, cheaper, and more efficient.
By H2O GlobalNews Calabasas
PUBLISHED Nov. 22, 2023
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How is the OceanWell process different from current desalination methods?
Desalination is a heavy industrial process, as it is currently practiced, that removes seawater (including small organisms) from the oceans for processing on land, filters out and disposes of those organisms and other impurities in landfills, either evaporates or pressurizes the filtered seawater, squeezes out as much fresh water as technically possible, and then disposes of a doubly-salty brine back into the sea where it can be toxic.
The Ocean Well uses a passive process driven by natural forces to harvest fresh water from the relatively lifeless deep sea:
It does not kill small organisms with chemicals. It uses the same reverse osmosis membranes as onshore desalination plants, but allows microscopic lifeforms to pass through the process unharmed.
It does not produce toxic brine. The feed seawater is not pressurized and only small amounts of fresh water are extracted, allowing its seawater discharge to stay near ambient pressure and salinity, such that is not toxic in any way. In fact, according to the California Ocean Plan, “discharges shall not exceed a daily maximum of 2.0 parts per thousand (ppt) above natural background salinity measured no further than 100 meters (328 ft) horizontally from each discharge point.” This equates to 5.7% above a 35 ppt background salinity typical in California. The Ocean Well maintains a discharge of only 5% above ambient ocean salinity, thus never producing “brine”.
It does not heat or pressurize the feed seawater. While it does pressurize the harvested fresh water in order to deliver it to shore, there is no marine life in the fresh water and this design cuts pressurization requirements in half, meaning lower energy requirements, lower carbon production, and lower operating costs.
Will the OceanWell help or hurt the earth and oceans?
The Ocean Well was intentionally designed to help the earth and oceans, inspired by the multiple functions of a mangrove root system: Its supports life on earth, using reverse osmosis membrane barriers to lightly draw fresh water from the relatively lifeless deep sea for use on land.It supports life in the oceans, by creating nutrient-rich habitats to feed marine life and subsea infrastructure to power ocean monitoring systems for learning more about the deep sea.
The Ocean Well will help rebalance Earth’s water cycle: As global temperatures rise, the moisture-holding capacity of Earth’s atmosphere increases, and climatological and hydrological patterns change. These changes may cause increases in global precipitation, more concentrated over the oceans than land, leading to increased aridification in many of today’s most habitable regions of Earth, including parts of North America, Eurasia, and Australia. For life as we know it to continue, we need to fix the broken water cycle and rebalance the distribution of our planet’s fresh water supply to sustain life on Earth.
Will it raise the cost of fresh water?
Ocean Well water will cost less, at a large scale, compared to today’s best desalination technologies in locations with deep seawater close to shore. Water prices are rising around the world as “free” sources of fresh water become exhausted: The Ocean Well cannot produce “free” water, but it uses up to 50% less energy per cubic meter produced than seawater desalination.
Depending on location, Ocean Well water may even be priced lower than stormwater capture, recycled wastewater, imported water, brackish desalination, and some conservation efforts. As an added bonus, the Ocean Well produces very cold water that can be used in once-through cooling applications before it’s consumed as drinking water, thus offsetting cooling costs. Synergies with other offshore renewables and climate technologies, such as wind power and carbon capture, may provide opportunities to further cut the cost of fresh water.
Why has this not been done before?
The Ocean Well combines proven technologies from the offshore energy and desalination industries: While the desalination sector has been relatively stagnant since its last major innovation in the late-1990s, the offshore energy sector is relatively young with major innovations in subsea systems occurring in the late-2010s.
The principles behind subsea reverse osmosis were theorized decades ago, but were technically infeasible, until now. Now, because of the development of reliable subsea technologies, the Ocean Well is not only feasible, but offers favorable economies of scale and unprecedented ecological benefits.