LIVING

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.