An almost infinite supply of an under-used resource could turn unfarmable land into lush fields and solve the world’s food crisis – at least that’s the hope. A decade on, have the projects worked?
While the coronavirus pandemic has highlighted the weakness of supply chains, for many people the fragility of our food networks is nothing new. Rising populations in water-stressed areas of the world increase the demand for food in the places it is hardest to grow, and the climate crisis is only making matters worse. The lack of freshwater is a serious threat to the survival of many people worldwide and drought caused by climate change compounds the issue.
The World Health Organization predicts that by 2025, half of the global population will be living in water-stressed areas, where the demand for clean, usable water surpasses the amount available.
But what if freshwater isn’t the answer? What if there was a way to feed the world without adding to the strain on our water supply? What if, in fact, there was an almost infinite source of water we could farm with?
Some innovators say the solution to saving our most precious resource might be right in front of us. “It’s wrong to say that water is a finite resource because it is an infinite resource; we just don't manage it very well,” says Charlie Paton, the UK-based founder and director of Seawater Greenhouse.
While the planet’s fresh water may be limited, the Seawater Greenhouse project harnesses the power of two things we do have an ample supply of – seawater and sunlight – to grow food in the middle of the desert.
Paton and his team have established successful seawater greenhouses in arid, sun-baked coastal locations like Oman, the UAE and Australia over the past decade, and most recently, Somaliland. Through an innovative method of desalination, these completely solar-powered greenhouse operations use saltwater – piped directly from the sea into wells – to create ideal growing conditions.
Some of the greenhouses are impressive operations – steel frame and glass buildings set in fields of solar arrays, while others are little more than canvas sheets wrapped around timber. But it’s what’s inside that counts. Rows of fruit or vegetables impossible to grow in a desert; juicy cucumbers, plump tomatoes and brilliant red raspberries defy the elements.
A close up of a pad shows the large surface area over which seawater evaporates (Credit: Sahara Forest Project Foundation)
The projects garnered international acclaim and in 2017, rising like a mirage out of the scorched earth 15km from the Red Sea near the Gulf of Aqaba in Jordan, came the Sahara Forest Project, a competitor seawater greenhouse site the size of four football fields.
Much like the landscape in Somaliland and parts of Australia, Jordan is a perfect candidate for seawater greenhouse technology: it has a hot, arid climate – the country is number five on the World Resource Institute’s list of most water-stressed countries in the world – and it is close to a saltwater source.
“Let's make use of what there is enough of on the planet, which is saltwater, sunlight, and deserts,” says Kjetil Stake, managing director of the project. “Let's use those resources to produce what we need more of, which is sustainably-produced food, freshwater and clean energy. Eighty percent of the freshwater that is being used today is used in agriculture. When we reach [a population of] 10 billion people in 2050, how are we going to produce food in a way which does not harm the planet?”
How to grow food from seawater
Inside the greenhouses, a cool, humid oasis of plants and vegetables flourishes. Fleshy fruits, salad leaves and velvety aubergines would all normally require large volumes of water to grow. But the beauty of a seawater greenhouse is that water can be reused efficiently.
As plants grow, they evaporate water through their leaves and flowers in a process called transpiration. Plants lose more water rapidly in hot, dry conditions. “It's the same thing as hanging a sheet out on the line to dry,” says Paton. “If it's a grey, cloudy day in the UK, it won't dry [but] if it's in the middle of Saudi Arabia, it'll be dry in 10 minutes.”
So, to grow crops in the desert, he explains, you need to recreate something similar to the soggy UK climate inside the greenhouse. The cooler, moist microclimate means plants require less freshwater and less irrigation, thereby reducing water usage and overall costs.
Seawater greenhouses make this possible with adapted pad and fan technology. Fans (or wind, in some cases) push air through water-soaked “pads” – layers of corrugated card hung vertically – producing a vapour that adds moisture to the greenhouse and drops the temperature by around 15C.
While traditional pad and fan systems use freshwater, seawater greenhouses make use of saltwater. The effect is the same. As the water is pushed through the pad, the salt is separated from the freshwater and this high-salinity water, called brine, is used to cool the greenhouse.
Paton says that brine is more effective than freshwater for this “evaporative cooling” purpose. Brine has both a higher boiling point and lower freezing point than pure water, which means it works better as a coolant. Heat energy is absorbed by the brine as water evaporates from it further, helping to cool the air around the pads. As it condenses, the desalinated fresh water irrigates the crops, revegetates the surrounding landscape outside the greenhouse and provides clean drinking water.
A misty plant oasis grows in the Jordanian desert (Credit: Sahara Forest Project Foundation)
And unlike traditional desalination methods, which can be costly and dump large amounts of salty brine back into the sea, disrupting fragile ecosystems, the seawater greenhouse model is eco-friendly. Any leftover salty brine that isn’t used in the cooling cycle is evaporated and made into salt. Paton says his aim is to achieve “zero discharge from desalination”.
Looking back to grow a better future
While the seawater greenhouse is a fairly novel idea, it brings together elements of technology and design that already existed – some of which have roots in the Middle East and north Africa. “Arabic architecture uses fountains and water cascading down surface walls and pools because they knew that evaporating water would cool the place down,” says Paton. “There are lots of old palaces in Iran that use sophisticated evaporative cooling systems to air condition themselves, so it's a very old technology.”
Residual water vapour creates an oasis effect that extends past the greenhouse and, by using desalinated water to revegetate the surrounding area, the Sahara Forest Project hopes to make a lasting change in the landscape, restoring today’s deserts into the forests they once were. “In my lifetime I’ve seen many parts of the world flipped from being reasonably wet areas with vegetation to being completely arid,” says Paton. Worldwide deforestation not only wreaks havoc on ecosystems but drastically reduces the number of trees that pull CO2 from the air, which offsets our carbon emissions. “We want to green the desert,” says Stake. “The larger areas we manage to green, the more carbon we would store in the soil.”
Revegetation could help mend the water cycle by facilitating the natural process of evaporation, eventually returning the water to the earth as rain. Increasing deforestation and urban development to meet the needs of a rising population have created a rift in this process. “Every time you cover a field in concrete or asphalt, you've reduced that component of evaporation,” explains Paton. “So, as society grows and develops, it does so without much concern for the water cycle.”
Another untapped benefit of seawater greenhouses is the ability to ‘mine’ elements like lithium, cobalt and magnesium from the brine
The theory is extremely attractive; take a resource we have plenty of and turn it into something useful, then take the by-product and put that to good use, too. How many farming practices are truly win-win-win like this?
Wind power has been used to cool homes in the Middle East for centuries (Credit: Alamy)
Plants flourished outside the greenhouses in Jordan after only a couple months, says Stake. Paton’s Seawater Greenhouse projects have seen similar success with revegetation. He says after two years the land around the site in Oman began to flourish. Though not all sites are as far ahead. Some do still appear to be lonely greenhouses standing in the desert – not quite the lush oases the projects aspire to be.
Economic viability
In addition to the environmental benefits seawater greenhouses offer, the technology could provide a major economic boost, green jobs, as well as the potential for agricultural self-sufficiency, allowing countries to rely less on imports, or in the case of places like Somaliland, food aid.
We are very climate-resilient and supermarkets like that – Paton
Seawater greenhouses offer the possibility of stable, climate-resistant agricultural production in places like Australia where a climate of extremes can make farming difficult. Seawater Greenhouse established a large commercial project with Sundrop Farms in Port Augusta, Australia that now produces 15% of Australia’s tomatoes. “We are self-sufficient in making our own freshwater and cooling and air conditioning,” Paton says. “We are very climate-resilient – and supermarkets like that.”
The Sahara Forest Project sells some of their vegetables at local markets in Jordan (though minimally so as not to cause friction with local growers), and the company also landed a major deal with Italian Costa and AIDA cruise ships, where their seawater veggies are incorporated into the on-board menus. This partnership is temporarily on hold while travel is restricted because of Covid-19 but is expected to resume post-pandemic. Plans are also in the works to export vegetables to Norway.
Paton says there’s potential for seawater greenhouses to play an additional role in providing more sustainable options for tourism growth. In Saudi Arabia, for instance, a massive tourism project is underway which will require enormous amounts of desalinated water. “If they pursue the ‘business as usual’ approach, the increased salinity from brine waste in the Gulf and Red Sea will have a seriously detrimental effect on all marine life,” says Paton. “If instead, they use [the brine] for evaporative cooling, the greening up and cooling down potential is colossal. If they also use renewable energy to drive the process, the carbon capture potential is even more colossal,” says Paton.
Life has returned to the desert around one of the Seawater Greenhouse projects (Credit: Seawater Greenhouse)
Another untapped benefit of seawater greenhouses is the ability to “mine” elements like lithium, cobalt and magnesium from the brine. These can then be sold for use in other industries. “There are fantastic volumes of lithium in seawater but it's very diluted,” Paton says. “But because we evaporate seawater, we end up concentrating the brine, which makes it much easier to extract valuable things from it.”
Mining minerals from brine on salt flats that have high concentrations of metals like lithium and magnesium has been a commercial endeavour around the world for years, but Paton is now to test extracting lithium from desalinated-seawater brine in Somaliland, where he will be partnering with Salt-Mine in the coming months.
Challenging the competition
Like many green industries, seawater greenhouses have faced challenges. At the outset, Paton says they were perceived as a threat to existing agricultural policies and partnerships. The technological success of an early pilot project in the Canary Islands led to pushback from stakeholders concerned about undermining the monopoly European growers benefited from under the Common Agricultural Policy. Seawater greenhouses could enable growers in places like Eritrea, for example – where an NGO had plans for a seawater greenhouse project – to compete with Europeans. So funding was pulled and the project shut down.
Local culture also factors into planning project sites. In Somaliland, for instance, Paton says that farming isn’t part of the culture, which can be a barrier to local engagement and investment. “[In Somaliland], agriculture tends to be looked down on as being hard work, only fit for the very poor... while camel and livestock ownership is the primary aspiration and indicator of wealth,” explains Paton. “Under such circumstances, a large, commercial horticultural operation [like we established in Australia] would be beset by land ownership conflicts, clan friction, mistrust of outsiders, and attempts to take over by one clan or another.” In order to establish successful seawater greenhouses in Somaliland, Paton and the team focused on implementing smaller, family-run projects.
Ruba Al Zubi, advisor to the president for science policy at Jordan’s Royal Scientific Society, says that an understanding of local attitudes toward agriculture is critical. “Technology, innovation and cultural transformation need to be addressed adequately,” she says. “[In Jordan, we need] a cultural shift in how the agriculture sector is perceived from a socio-economic angle… and communication around agriculture as a key economic sector for Jordan to encourage transformation on a national level.” The Sahara Forest Project has been pivotal in making this happen. “Showing the impact on productivity and socio-economic development is a real marketing tool for the transformation we aspire to and for mobilising efforts and support,” says Al Zubi.
Projects like this can also demonstrate the possibilities of a triple bottom line: when done right, Stake says, business can be good for people by creating jobs, good for the planet, and profitable. “We want to be an inspiration for others,” he says, “to show that it is possible to make money doing good business.”
Like the implementation of any new green industry, scaling this technology will likely mean overcoming obstacles – cultural, economic, and otherwise. But in the deserts of Jordan, Somaliland, and elsewhere, the plump, technicolour plants and vegetables grown in seawater greenhouses are blooming beacons of hope.
This article is part of Follow the Food, a series investigating how agriculture is responding to environmental challenges. Follow the Food traces emerging answers to these problems – both high-tech and low-tech, local and global – from farmers, growers and researchers across six continents.
