Catalonia prepares to turn the sea into a large reservoir

There are people from Barcelona who don’t know it, but much of the water that comes out of their taps every day comes from the sea. It is extracted by a 500 meter long tube submerged in front of the airport and which, like a gigantic mouth of water, absorbs and transports thousands of liters to the El Prat desalination plant. It is the great locomotive that, from the mouth of the Llobregat River, makes water drinkable and guarantees the supply to millions of homes in the greater Barcelona. Since it opened in 2009, the largest desalination plant for human consumption in Europe has not accumulated so many months (a total of six, since last January) at such a high level of production: it is generating 140 million liters a day ( to 70% of its full capacity). The reason is that it hardly rains.

Apart from being one of the driest of the century, the year 2022 has turned into the present the bad omens that climate experts have been warning about for decades. Today, the Catalan reservoirs are 30% below the historical average for these dates (at 58% of their capacity). And it is that in Catalonia, as in the rest of the communities of the Mediterranean coast, the perfect ingredients of the climate crisis are intermingled: decrease in rainfall, high population density, agricultural extensions that empty the reservoirs and mass tourism that in small municipalities of the Costa Brava and the Balearic Islands force the tap to be cut off due to the shortage of liquid in summer.

Today, the Catalan reservoirs are 30% below the historical average for these dates (at 58% of their capacity)

By the middle of this century, the Generalitat calculates that it will rain 7% less and that the contribution of water from internal basins will be reduced by 18%, according to the 2022-2027 hydrological plan, which projects a multimillion-dollar investment of more than 2,300 million in five years to guarantee supply for future generations. It will be done through the construction of new desalination plants and other reuse plants, among other measures. The Government is also committed to improving the poor quality of groundwater: 7 out of 10 Catalan aquifers still do not meet European criteria after decades of abandonment.

In desalination alone, the Generalitat wants to allocate up to 176 million and double its production capacity to go from 80 to 160 hectometers (hm³) per year. The Tordera desalination plant will go from 20 to 80 hm³ and a new plant will be built in the Foix basin. The idea is to recover by sea the water that will be lost by the sky. “In the end, what it is about is trying to supply when what is in the reservoirs is not enough,” says Carlos Miguel, head of the El Prat Desalination Plant, whose structure, he explains, is already unfeasible to expand. “It is too big for the land that is available here”, says Miguel about this plant, managed by Aigües Ter-Llobregat and sandwiched between the Port and the Barcelona Airport.

The Generalitat wants to double its desalinated water production capacity: from 80 to 160 hectometers (hm3) per year. The idea is to recover by sea the water that will be lost by the sky.

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In the desalination process, the liquid passes several filters in different plants in which particles are removed, from sand to microplastics, for example. The most expensive process occurs last, in a huge room with 8 racks and tons of green, lilac, blue and gray tubes. The noise generated by the 2,000 kW motors to rotate the water in a spiral at thousands of revolutions between membranes and carry out the osmosis process is deafening. At the end of the process, for every 100 liters of seawater that is extracted from the sea, 45 liters are obtained that are fit for human consumption.

The process entails, however, enormous energy consumption. To make a cubic meter of water drinkable, more than 3 kilowatt hours (Kwh) are needed. It is the whiting that bites its tail: to alleviate the lack of rain caused by climate change, a large amount of energy has to be generated, which is why it pollutes more. The alternative, however, is to run out of water. “The Mediterranean climate has many limitations. Hence, desalination is essential on our coast or in the Balearic Islands. Natural resources are not enough to supply the current demand”, adds the engineer among dozens of colored deposits of a structure of pharaonic dimensions.

An image of the interior of the El Prat de Llobregat desalination plant.
An image of the interior of the El Prat de Llobregat desalination plant.
Christopher Castro

The Barcelona metropolitan area, with more than 15,000 inhabitants per square kilometer, is one of the densest territories in Europe. And also ground zero of the climate emergency in the Mediterranean region. A 2012 report from the Barcelona Chamber of Commerce warned of this fact and explained that the city was not prepared to face a period of drought that would last three years. Sources from the technical team that prepared the report value a decade later that the ability to respond to the lack of rain has improved significantly since then. But they add that today the community still has to improve its reuse capacity: only 6% of the water that is purified is reused in agricultural or industrial uses. The rest is thrown into rivers and the sea.

Among the actions scheduled by the Catalan Water Agency of the Generalitat is the construction of 25 regeneration stations. That is, plants to treat purified water and reuse it later for other uses, such as agriculture or industry. The example to follow is Tarragona, where most of the purified liquid is later reused through Aguas Industriales de Tarragona (Aitasa).

Scarcity also leads municipalities to use their intelligence and imagination. In El Prat de Llobregat (Barcelona), for example, the Consistory intends that the future 3,000 homes in a projected neighborhood in the south of the city will have a reused water tank from the outset. A measure that, according to calculations by the manager of the municipal water company, Aureliano García, would mean saving up to 25% of domestic drinking water. “It’s a way to maintain resources… it will also mean a reduction in the rate,” says Garcia, who warns that there are aquifers that today are “in the UCI.” The reality is that reclaimed water is here to stay… ”, he adds.

Tourism dries the Balearic Islands

In the last six years, the production of desalinated water in Mallorca has increased fivefold and in Ibiza it has increased by 43.19%. And in the next five, the Government of the Balearic Islands wants to further increase its capacity, explains Joana Garau, General Director of Water Resources. “Given the general lack of water, our strategy is to stretch the water resources, which come from the aquifers, to the maximum, in order to extend their use until summer without emptying them,” adds Garau. The senior government official explains that the water policy has changed in recent years on the islands and that although before it was decided to finish all the underground tanks before starting the desalination plants at full speed, now the objective is to use the eight desalination plants of the islands for 12 months to drain the resources as little as possible. In the Balearic Islands, urban consumption takes 70% of the islands’ resources.

According to a recent study by the University of the Balearic Islands (UIB), one in every four liters of the islands is consumed by tourism. In Formentera, the smallest of the inhabited islands of the Balearic Islands, the use of purified seawater accounts for up to 80% of the total used on the islands. For the older generations, who were dedicated to agriculture, the small aquifer on the island was enough for them. Today, despite having just over 12,000 inhabitants, according to INE data, the island has a desalination plant with a capacity to generate 7,000 cubic meters of drinking water per day. This is so because summer the paradisiacal island sees its population almost triple.

In neighboring Ibiza, desalinated water accounts for 70% of the drinking liquid consumed. It is the Spain that drinks water from the sea. “Right now the situation of the water reserves is normal. But after the summer it is very likely that in many places a pre-alert situation for drought will be declared. The problem will arrive in autumn and winter”, concludes Garau.

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