On a scorching day in late June, tourists filled cafes and hotel rooms along Spain’s Mediterranean coast, including in Torrevieja, a small town of tightly stacked apartment blocks along a curved beach.
The seasonal population growth in this dry, sun-drenched region could overwhelm water reserves if it weren’t for a row of buildings overlooking a pink lagoon nearby.
These low structures house an extensive network of pipes, pumps and tanks of a plant that performs a kind of alchemy that is crucial to the economy of this part of Spain: it takes enormous amounts of water from the sea, removes the salt and produces more than 60 million gallons of fresh water a day.
Spanish company Acciona, which built the plant, says the plant can supply water to 1.6 million people through a process called desalination. For much of the year, however, the amount produced is used primarily to grow oranges, lemons and other crops for consumers in northern Europe.
But when the tourist crowds arrive in the summer, more water is diverted into the city’s pipes for showers and other domestic uses, says Ana Boix, the plant’s deputy director. “We have very high quality water from an inexhaustible supply,” she says.
The Torrevieja power plant is the largest of its kind in Europe, and similar plants can be found along the Spanish coast. They have enabled unbridled coastal development in arid areas and supported an agriculture that is among the most competent in managing water in the world.
With nearly 100 large plants, Spain is the largest user of desalination plants in Europe and one of the largest in the world. Many other countries, including Australia, China and Israel, are increasing their dependence on desalination plants for drinking water supplies and other purposes.
Christopher Gasson, editor of industry magazine Global Water Intelligence, estimates that around 500 million people rely at least partially on purified salt or brackish water, and that this number could rise sixfold to three billion by mid-century. There are around 1,500 large plants worldwide – those capable of producing around 2.6 million gallons a day – with around $14 billion being spent annually on operating existing plants and building new ones.
Several factors make further growth almost inevitable. Coastal cities are attracting more and more people living in places where there is not enough water. And climate-induced droughts are becoming more frequent and severe. Governments are therefore opting for desalination plants to hedge not only against water shortages but also against potential social unrest.
“I think water will continue to be a particular concern, especially in the era of climate change,” said Peter S. Fiske, executive director of the National Alliance for Water Innovation, a research organization funded by the U.S. Department of Energy.
Given increasing supply pressure and tighter regulations, companies may also need to invest in desalination to ensure the viability of their factories.
In addition, the operating costs of energy-intensive desalination technology – so-called reverse osmosis, which is standard in large plants such as the one in Torrevieja – are reduced by combining water treatment with low-cost solar energy, encouraging the construction of new plants.
The lack of water resources in the Persian Gulf countries, combined with their abundance of oil and sunshine, makes building desalination plants an obvious choice. “Desalination tends to be needed where there is sunshine,” said Mr Gasson, using an acronym for desalination.
The largest market for these plants is Saudi Arabia, followed by the United Arab Emirates. Access to treated seawater has contributed to the creation of shiny, futuristic metropolises in places like Dubai and Qatar.
“Desalination has made this spaceship-like settlement possible,” said Karim Elgendy, a climate analyst at Chatham House, a London-based research organization.
There are fears that the reliance of countries like Saudi Arabia on desalination could leave their citizens scrambling for water if coastal facilities fail or are attacked. Desalination is “the only way to continue to have large population centers in the region,” said Karen E. Young, a senior fellow at Columbia University’s Center for Global Energy Policy.
Some analysts say concerns about water shortages and the high investment in desalination plants are likely to lead to breakthroughs that are cheaper, cleaner and more flexible. Sheikh Mohammed bin Zayed Al Nahyan, ruler of Abu Dhabi, the capital of the United Arab Emirates, is offering a $119 million prize to encourage innovation in the field.
“You could actually call it the ChatGPT moment for water,” said Adri Pols, CEO of a Dutch water startup called Desolenator, referring to the hugely popular artificial intelligence chatbot. His company offers solar-powered systems that can be packed into shipping containers and shipped to businesses and farms.
But customers complain that desalination is still more expensive than using rainwater and has other disadvantages. The Spanish government subsidizes most of the costs, but Mariano Saez, a farmer in the region near Torrevieja, says the 45 cents he pays per cubic meter to produce 30,000 tons of citrus fruit annually is still too expensive.
Spain’s rivers should be redesigned to supply more water from other regions that would be “cheaper and healthier than the water from desalination plants,” he said. But some analysts say this approach is impractical and leads to discord.
“Economic development will continue and needs a water supply,” said Jorge Olcina, professor of geography at the nearby University of Alicante.
The Spanish government recently announced a 90 million euro (about 98 million US dollars) expansion of the Torrevieja power plant, which cost about 200 million euros (about 217 million US dollars).
Santiago Martín Barajas, a representative of the environmental group Ecologistas en Acción, said the concentrated salt water flowing from the plants into the sea could harm marine life, including the marine vegetation in which fish reproduce. Mr Barajas said desalination should be limited to drinking water supplies, especially in times of drought, and should not be used to irrigate crops.
Acciona, the company that built the Torrevieja plant, employed environmental consultants to regularly examine the seawater and sediment around the pipes outside the city’s seawall through which the plant’s wastewater flows to ensure that the elevated salinity remained within regulatory limits.
Environmental concerns have limited the construction of plants in some places, including California, where desalination would otherwise be a logical option for dealing with severe droughts. In 2022, a state panel rejected a $1.4 billion proposal to build a plant in Huntington Beach, near Los Angeles, that could have provided 50 million gallons of drinking water a day.
Acciona, which was to build the plant in California, sees many other possibilities. The company says it has the best chance of designing, building and operating a smaller plant in Dana Point in Southern California. The company has also agreed to build Africa’s largest desalination plant near Casablanca in Morocco. The cost is almost a billion dollars and the energy supply will be provided exclusively by wind power.
