The high price of desalination

Demand for water puts pressure on Gulf ecosystems

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 pro- cess 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. 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 gases.

Consumption is expected to increase in the region from 42 cubic kilometres per year in 2012, 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 an estimated additional 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 affect 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 Government to install more efficient methods.

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, said Zitouni Dada from the United Nations’ environment programme. Some have suggested using 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 that there is a single solution to the issue and instead are promoting a holistic change for the process.

“The UAE is doing a lot already, in terms of policy and has set a clear agenda, but for me, quite frankly, what it needs to do now, which they do reasonably well, is to execute,” said Paddy Padmanathan, president of Saudi Arabian energy company Acwa Power. “You have the institutions, monitoring mechanisms, and 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 plans to do more research to discover other methods of desalination. As yet it has conducted only pilot projects and not full implementation.