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Abu Dhabi, UAEMonday 21 May 2018

Demand for desalinated water puts pressure on Gulf ecosystems

According to the Ministry of Climate Change and Environment, 96 per cent of domestic consumption of water – from drinking water to showers – comes from one of the 70 desalination plants located in the UAE.

Ninety-six per cent of domestic consumption of water comes from one of the 70 desalination plants located in the UAE, such as this one in Dubai. Sarah Dea / The National
Ninety-six per cent of domestic consumption of water comes from one of the 70 desalination plants located in the UAE, such as this one in Dubai. Sarah Dea / The National

Domestic consumption of desalinated water in the region is not only carbon-intensive but contributes to making the Arabian Gulf one of the world’s most salty and potentially most uninhabitable bodies of water, experts say.

According to the Ministry of Climate Change and Environment, 96 per cent of domestic consumption of water – from drinking water to showers – comes from one of the 70 desalination plants located in the UAE.

The science behind the process brought to the region to service the oil-driven population boom in the 1960s has remained unchanged. Boil seawater to evaporate H2O, remineralise the purified water, and deposit the byproduct, brine, back into the Gulf.

Desalination

The environmental hazards are twofold – desalination plants need lots of energy that is generated by the burning of fossil fuels, and they deposit harmful byproducts into a Gulf with currents weak enough to be likened to that of a great lake.

The GCC’s desalination plants alone account for 0.2 per cent of the entire world’s electricity consumption, about 38 TWh per year – energy enough to match the UAE’s total consumption for more than four months.

With gas and oil being the primary sources of energy, the UAE’s desalination plants are one of the leading contributors to greenhouse gasses. Consumption is expected to increase in the region from 42 cubic kilometres per year in 2012 today to 200 cubic kilometres by 2050.

Brine, the residual saline slush from desalination, is produced at a 1:1 ratio of freshwater production. For every litre of fresh water delivered to our homes a litre of high-salinity brine is deposited back in the Gulf.

Over decades, brine pollution in the Gulf has amounted to hundreds of cubic kilometres with about another 40 cubic kilometres of high saline water deposited into the Gulf every year.

“Desalination plants discharge high-temperature brines, detergents and metals, which can all adversely affect marine habitats such as coral reefs and seagrass meadows. The intakes of desalination plants can kill fish and crustaceans by impinging these organisms on intake screens,” the Environment Agency’s Abu Dhabi’s marine quality report said.

The brine, released into a body of water so low in current, is expected to stay and effect marine life significantly in the region.

“In that case, besides the increase in the already extremely high cost of desalination, special efforts will be needed from the government to mitigate the negative impacts of the brine disposed in the Gulf on the ecosystems,” said a report by MDPI, an academic journal based in Switzerland.

Many conventional desalination installations will near the end of their operational life over the next few years, providing a chance for the UAE Government to retrofit and install new, more efficient methods of desalination.

The desalination process uses a lot of energy but in many Gulf countries this energy use is subsidised. Removing subsidies could encourage the private sector to devise more efficient processes, Zitouni Dada, from the United Nations Environment Programme, said.

Some suggestions have been to use solar power, used in a pilot programme by Masdar, or to harness the heat generated from the process towards other uses. But most scientists are sceptical of a single solution, instead promoting a holistic change in the entire process.

“The UAE is doing a lot already, in terms of policy has set a clear agenda, but for me, quite frankly, what the UAE needs to do now, which they do reasonably well also, is to execute,” said Paddy Padmanathan, president of Saudi Arabian energy company Acwa Power. “You have the institutions, monitoring mechanisms, that’s why you are showing some leadership in this area.”

Another idea is to tackle excess brine by combining the slush with municipal wastewater to dilute the salinity.

Other technologies, osmosis and reverse osmosis, use chemistry and basic principles of physics to funnel seawater through filtration devices. However, the elements and chemicals used in osmosis also have a negative effect on the environment, as does the release of heat during the process.

Masdar has plans to put more energy into discovering other methods of desalination, but as yet have conducted only pilot projects and are yet to announce full implementation.

nalwasmi@thenational.ae