Is desalination the answer to water scarcity?

Sarah Murray
Journalist, Financial Times/Economist Group
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For dry regions like the Middle East and North Africa, desalination has long been part of national water strategies. As a whole, the region accounts for half of the world’s desalination capacity and is home to some of the largest desalination plants.

Interest in and investment in desalination are expanding beyond this part of the world, however, driven in part by water-scarcity concerns—14% of the world population is expected to live in water-scarce areas by 2025.

The overall result has been a 57% increase in installed capacity in just five years, reaching 20bn gal/day globally, according to Global Water Intelligence. In the face of droughts, for example, the US is building its largest-ever seawater desalination plant. Located in Carlsbad, California, the plant should provide 50m gal/day and start operations by the end of this year.

Growing demand is not the only driver of increased investment in desalination—the technology has become more economically viable as well. New materials like graphene can cut operational costs, for example. Meanwhile, improved membrane performance for reverse-osmosis desalination—today’s dominant technology—has increased operational efficiency, as have mechanical energy-recovery devices like pressure exchangers and advances in ancillary hardware such as pumps.

Reverse-osmosis desalination remains an energy-intensive process, however. “Most of the electricity comes from coal and natural gas, which is very water-intensive—you’re basically using water to make water,” says Kate Zerrenner‬, Texas-based climate and energy project manager at the Environmental Defense Fund. “So renewable has huge potential here.”

While the falling cost of solar PV (photovoltaic) systems is helping, there is still some way to go before renewable-powered desalination becomes competitive with fossil-fuel alternatives. “Today, $3 or $4 a cubic metre will buy you solar-desalinated water, while the best available non-solar desalination will produce it for 50 cents,” says John Lienhard, director of the Center for Clean Water and Clean Energy at the Massachusetts Institute of Technology. “But we believe that’s a gap that can be bridged.”

So does the Aramco Entrepreneurship Center, which, in collaboration with GE, set up an open innovation challenge last year to identify promising renewable desalination technologies that could reach the 50-cent mark while meeting the World Health Organisation’s potability standards. Among the winning technology groups announced in January 2015 was TNO, a Dutch nonprofit working on the simultaneous production of potable water and power using high-pressure membrane distillation driven by solar heat. In addtion, the Masdar Institute in Abu Dhabi has begun a renewable energy desalination test programme with the aim of reaching commercial scale by 2020.

For now, desalination remains a higher-cost option than many other water-recycling technologies. And until renewable sources of power are widely used, it comes with its own environmental footprint. But as water scarcity spreads, those searching for water will increasingly turn to desalination.

This article is published in collaboration with GE Look Ahead. Publication does not imply endorsement of views by the World Economic Forum.

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Author: Sarah Murray writes for GE Look Ahead. 

Image: A desalination plant is pictured in Antofagasta, Chile. REUTERS/Julie Gordon (CHILE – Tags: ENVIRONMENT ENERGY BUSINESS COMMODITIES)

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