Desalination, a key issue for the future
Freshwater reserves account for just 2.53% of the water on our planet and just 1 millionth of global resources is usable. 39% of the world population lives less than 100 km from the coast. These findings highlight the potential for the desalination business conducted by Degrémont, a subsidiary of SUEZ ENVIRONNEMENT, since many water-stressed regions could potentially use this technology to meet their water needs for drinking, industry or for irrigation.
There are two main desalination techniques:
• Distillation is the oldest technology. It combines evaporation with condensation to ensure a final salinity of less than 10 mg/L.
• Reverse osmosis, the most recent, is a process developed by SUEZ ENVIRONNEMENT which, as a result of pressure, allows over 99.9% of dissolved salts present in the water to be retained using a membrane filter.
Desalination currently produces around 1% of the world’s drinking water. However this figure hides disparities between regions of the world because in fact it now covers 20% of the drinking water requirements of the continent of Oceania.
The case of Australia
In April 2005, the public Water Corporation authority of Western Australia chose Degrémont, a subsidiary of SUEZ ENVIRONNEMENT and a pioneering user of reverse osmosis desalination technology, to design, build and operate the first seawater desalination plant in Perth. With a daily capacity of 143,000 cubic metres, the Perth plant, which has been in service since October 2006, includes seawater capture and pre-treatment facilities, reverse osmosis desalination systems and pumping and remineralisation units.
Degrémont is currently completing the construction of a second plant in Australia, which will cover one third of the water requirements of the Melbourne urban agglomeration by December 2011. Situated 80km from the city, on the Bass Strait, it is the biggest desalination plant in the southern hemisphere. Built with respect for the environment, it will produce 450,000 cubic metres of desalinated water per day using renewable energy produced by a wind farm. Australia has found an effective technology in desalination for combating a twelve-year drought.
250 desalination plants across the world
250 desalination plants have so far been built by Degrémont across the world, covering the drinking requirements of 10 million inhabitants. In the United Arab Emirates, located in the area of the world where the greatest recourse is made to this technology, the Fujaïrah plant uses a new “hybrid” approach that combines the two desalination techniques. This technology allows desalination to be achieved by reverse osmosis and by using thermal power. It therefore produces 250,000 cubic metres of water per day using 5 MSF (multiflash distillation process) units connected to a power station and 170,500 cubic metres per day by reverse osmosis. The water produced is mainly used for irrigation in the Al-Ayn region in order to compensate for the increased depletion of groundwater.
In Spain, the El Atabal plant provides a real solution to a prolonged reduction in the quality and quantity of water resources in Málaga by producing 165,000 cubic metres of desalinated water per day. Spain is the European leader in producing desalinated water. In 2009, Degrémont also opened Europe’s biggest desalination plant in Barcelona, with a drinking water production capacity of 200,000 cubic metres per day. The plant supplies drinking water to 20% of the population in the Barcelona area, i.e. 1.3 million inhabitants.
A futuristic solution that takes respect for biodiversity into account
The desalination market is growing strongly at the moment. Our water requirements are increasing and our reserves of good quality water are falling. This technology is one of the solutions available to compensate for the lack of drinking water, given the abundance of the raw material: sea water and brackish water. This growth must be achieved with respect for biodiversity. For this reason, for the Melbourne site, Degrémont wants its desalination plant to be self-sufficient in terms of energy, benefiting from two large wind farms capable of generating over 350,000 MW, which is equivalent to its average consumption. Ultimately, this opens the way for the effective pairing-up of state-of-the-art production plants with green energy production technology that is perfectly suited to the surrounding environment (including tidal, wind and underwater turbines), which will even enable these plants to produce an energy surplus.
Photo Credits: © SUEZ ENVIRONNEMENT / Abacapress / Michel Martinez Boulanin
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