A shocking way to make fresh water could be the UAE’s answer to desalination
As essential as oil has been to the rapid transformation of the UAE, it is the challenge of producing sufficient drinking water, at a reasonable cost, that must be met if the growth and development of the nation is to continue.
Nearly all the water consumed in the UAE, and the rest of the arid Arabian Gulf region, is extracted from seawater, using energy-intensive processes that consume precious fossil fuels.
Ever since the first small desalination plant was installed on Abu Dhabi’s Corniche in the early 1960s by Scottish engineering company Weir Westgarth, that has been the apparently intractable equation the Government has had to balance.
The latest figures from the Statistics Centre Abu Dhabi, published last month in its 2014 Environment Statistics report, show that the consumption of desalinated water in the emirate of Abu Dhabi has all but doubled since 2005, from 667 million cubic metres to 1.126 billion cubic metres by last year.
The increase between 2013 and last year alone was an insupportable 6.6 per cent.
In addition to the costs in terms of fossil fuels, said the report, there was an additional environmental price to be paid in the effect on the waters of the Gulf, where “salinity is relatively high because of combined influence of restricted exchange of Gulf waters with the open ocean, the high evaporation rates caused by high temperatures, and the desalination industry”.
According to a report published last month in conjunction with next year’s International Water Summit in Abu Dhabi, during the next five years the combined desalination capacity of the GCC countries as a whole is expected to increase by an astonishing 40 per cent — from the current 18.18 million cubic metres a day to more than 25 million cubic metres a day.
Research carried out by MEED Projects in conjunction with next January’s International Water Summit in Abu Dhabi has found that during the past decade GCC countries have invested US$76 billion in water projects, and that the planned increase in capacity would cost at least as much again.
But through economic necessity, “a major driver” of this investment will be “developing less energy-intensive methods of desalinating water”, says MEED.
That is why all eyes in the Middle East desalination industry would doubtless be focused on an apparently cheap, simple and efficient new technology, developed at the Massachusetts Institute of Technology, which will radically change the way that drinking water is produced from seawater.
The most common form of desalination in use, and the most cost-effective, is reverse osmosis, in which seawater is forced under pressure through a membrane that strips out the salt.
Alternative systems, which rely on heat evaporation, use up to five times as much power to run. Nevertheless, reverse-osmosis still consumes a lot of energy.
According to an analysis published last month in Physics Today, a latest-generation large-scale reverse-osmosis seawater desalination plant would use up to 4 kilowatt hours of energy to make a cubic metre of fresh water — about as much energy as it would take to operate an air conditioning unit for an hour on a hot day.
And this is as good as it is going to get. Reverse-osmosis technology was developed in the 1950s and since then great strides have been made in efficiency.
But the reality, said Physics Today, is that “with modern reverse-osmosis we cannot expect order-of-magnitude improvements to energy consumption — we’re already pretty good”.
Under these circumstances it isn’t hard to imagine that an entirely revolutionary system that used, by comparison, next to no energy, might take the world of desalination by storm.
Enter the MIT team led by Martin Bazant, professor of chemical engineering and mathematics, which has developed what it calls “a fundamentally new and different separation system”.
Gone are traditional energy-intensive filter systems — prone to clogging — or fuel-hungry heat-driven evaporation processes. Instead, Prof Bazant and colleagues have developed something they are calling “shock electrodialysis”.
Details of the new system are disclosed in a paper in the current edition of the journal Environmental Science and Technology Letters.
Seawater flows through a porous material made of tiny glass particles, sandwiched between electrodes. An electric current flows between the electrodes and causes the salty water to separate “into regions where the salt concentration is either depleted or enriched”.
When the current is turned up, at a certain point it generates a shock wave between the two zones, “sharply dividing the streams and allowing the fresh and salty regions to be separated by a simple physical barrier at the centre of the flow”. There is no expensively generated force, or heat. The charged salt particles, or ions, says Bazant, “just move to one side”.
It’s one of those ideas that sounds so simple it has people scratching their heads and wondering why no one has thought of it before.
The technology has already moved beyond theory. The real breakthrough, says Prof Bazant, is that his team has engineered “a practical system”, and the next step is to produce a scaled-up version for further testing.
Initially, says MIT, the process “would not be competitive with methods such as reverse osmosis for large-scale seawater desalination”, but further development — and investment — could quickly change that.
In the meantime, in addition to the promise of much cheaper desalination on a large scale, the new technology could have other applications, such cleaning up contaminated water.
And unlike some other approaches to desalination, “this one requires little infrastructure, so it might be useful for portable systems for use in remote locations, or for emergencies where water supplies are disrupted by storms or earthquakes”.
Whether this new technology will become an economic lifeline to regions such as the Gulf remains to be seen — too much has been invested in traditional systems to simply abandon them overnight — and governments throughout the Gulf are already working hard on the problem.
“As oil revenues decrease and the issue of water has risen up the political agenda, governments have acted to try to dampen demand and reduce capital and operational expenditure,” says Ed James, the director of content and analysis at MEED Projects.
“For example, earlier this year Abu Dhabi imposed water tariffs for the first time for Emiratis while increasing existing prices for expatriate users as a means of decreasing subsidies and lowering demand.”
Dubai increased water charges in 2010, helping to slow annual growth in the Emirate’s water usage from 10 to 4 per cent.
Nevertheless, in 2013, the UAE’s largest combined power and desalination plant opened in Dubai. Built alongside the existing plants at Jebel Ali at a cost of Dh10 billion, M Station uses gas to generate steam and produce up to 140 million gallons of water a day.
When it comes to new technology, perhaps the potential for the biggest breakthrough lies in a pilot programme launched in 2013 by Abu Dhabi’s Masdar Institute of Science and Technology, to research and develop desalination technologies that can be powered by renewable energy.
Four companies were selected to build four small-scale demonstration plants, the performances of which will be assessed in July next year, with the aim of bringing a full-scale commercial facility online by 2020.
Despite such innovative efforts, Ed James says “greater awareness and discussion is needed more than ever before around sustainable practice” in the region.
This will be one of the key areas of discussion at January’s International Water Summit, part of Abu Dhabi Sustainability Week. Perhaps someone should send an invitation to Prof Bazant at MIT.
Updated: November 16, 2015 04:00 AM