Drinking seawater

Since 1973, the Barcelona area has suffered seven serious droughts. The latest and most severe water crisis came to a head during the summer of 2008, when the city was forced to load emergency tankers of fresh water from Tarragona and ship it by sea to Barcelona. Water was restricted for some uses like filling swimming pools or watering gardens, and rationing of home use was a real possibility until the rains relieved the looming disaster. Needless to say, both the cost and inefficiency of shipping water to Barcelona were hard to swallow for residents of a city that is between two rivers, surrounded by a mountain range and faces the world’s third largest sea.

“We must turn this drought into an opportunity,” proclaimed Manuel Hernández, the director of the Agència Catalana de l’Aigua, (Catalan Water Agency), in an interview with Catalunya Radio in February 2008. The result was a decision to invest deeply in desalination technology, the process of taking salt out of seawater. The PlanAgua, proposed by the national government and signed by local entities, aims to create 20 such desalination plants along the coast before 2012. The cost is estimated at €178 million, with 75 percent of that money coming from the EU. The goal is to prevent municipal ‘water wars’, while allowing Catalunya to become less reliant on rain, well and river water.

At the moment, there are three desalination plants in construction or functioning along the shores of the Llobregat River, Barcelona’s main source of drinking water. The most visible is being built behind El Prat airport on the beach, set right in the middle of a Natural Park and bird sanctuary. This plant was initially scheduled to be up and running by now, but the opening date has been delayed until August. The other two are upstream, in Sant Joan Despí and Abrera. Theoretically, these plants should be treating fresh water, but due to river mismanagement and mining waste further upstream, they are filtering saltwater, or at least ‘industrial’ water. The expansion of the Abrera plant means it is now the largest in the world. When finished, these projects will produce 20 percent of Barcelona’s fresh water.

From the environmental point of view, the side effects of desalination seem to make it the best option for dealing with water shortage. “From the studies we have read, yes, there will be some changes, we have no idea how it will affect the birds and the marine life in the long term,” commented Jordi Fernández, a biologist working at the Xarxa de Parcs Naturals. “In the short term, I don’t see any serious problems. It is much better than draining a river or swamp so people can fill their swimming pools.”

The most common process of desalination is called ‘reverse osmosis’. This involves removing salt and other minerals by pushing seawater through a series of ‘membranes’ (filters) at extremely high pressure. For every 100 litres of seawater filtered, 45 litres of drinkable water is produced. The waste produces a brine, or film of salt, which is disposed of by pumping it back into the sea where it dissolves. At the moment, studies suggest that it will not negatively affect local eco-systems. However, an environmental worry is caused by the point of intake, an open pipe that is 2.5 kilometres offshore. The concern about sucking in local sea life and plankton has been addressed through strong filters, low speeds and meshed cages, as well as an audio technique that keeps larger fish away. So, except for a massive eyesore on a lovely beach already affected by low air-traffic, the environmental issues seem to be covered. At least until the question of how the plants are powered is raised. The only hitch in the apparently perfect world of desalination is the energy it takes to run the process. The trade-off between fresh water and carbon dioxide emission (or nuclear waste) is an equation that scientists are sweating over, and figures are not easy to calculate until the process is up and running for a while so exact data can be obtained.

Desalination has a long history and could be said to begin with Moses, in the book of Exodus, when he came across the bitter waters of Marah: “…the Lord shewed him a tree, which when cast unto the waters, the waters were made sweet.” Alternatively, the credit could go to Thomas Jefferson, who in 1791 drafted a technical diagram that was posted on board all US ships to prevent deaths caused by thirst. By the end of the 1800s, simple desalination equipment had become standard issue on all ships and an essential part of the maritime steam engine.

The largest full-scale desalination plants were built in the Middle East following the Second World War. In Europe, Spain pioneered the process in 1964 on Lanzarote, one of the Canary Islands, and over the past 45 years Spanish companies have built over 700 plants worldwide, providing drinking water to more than eight million people. Spain is the world’s fourth largest user of desalinated water, behind Saudi Arabia, U.A.E. and Kuwait. The desalinating process, water treatment, pipe infrastructure, research and development, plant servicing and the supporting products that are involved, such as filters and pumps, are helping to keep the Spanish economy afloat in the current economic crisis. Their international presence, in more than 24 countries, and with more than a quarter of the global market share, is a solid force in maintaining Spanish jobs and sustaining a continuous flow of drinkable water for thirsty people around the globe.

“My hunch is that desalination is the low hanging fruit, and if we are lucky it will improve drinking water quality, restore the ecological integrity of the Llobregat river and reduce treatment costs,” according to a Catalan Ph.D student at the University of Illinois, who asked not to be named.

Although Spain, and especially Catalunya, are gambling on the desalination technique to solve their water problem, the odds are in their favour, especially considering the latest developments in solar and wind energy as power sources. The plant in Abrera has just been named ‘Desalinator of the Year’ by Global Water Intelligence, a leading market analyst for the international water industry. The Abrera plant is producing a high quality of potable water, exceeding the EU standard and using a low energy consumption rate. At the recent opening of the Abrera expansion, José Montilla, President of the Generalitat, announced, “If it rains or not, we will have water. If drought comes, we are prepared. After this extraordinary investment, the problems of the past should not happen again.”

At the same event, Francesc Baltasar, Environmental Minister for the Generalitat declared, “We will have better tasting water at a lower price. Each home should save between €35 and €45 a year.”

If that turns out to be the case, the new desalinators are likely to receive a warm welcome from most people.

More info:

Global Water Intelligence—www.globalwaterintel.com

Xarxa de Parcs Naturals—www.diba.es/parcsn

For an analysis of Spain’s water resources—www.adu-res.org