Edge of Innovation

Can technology help avert a future global water crisis?

Think it won’t happen here? In January, the World Economic Forum announced that a water crisis is the number one global risk based on impact to society (as a measure of devastation), ahead of the spread of infectious diseases and weapons of mass destruction.

Still think it won’t happen here? The 2014 drought in California proves that it’s not just developing nations who are struggling.

Even in years with normal rainfall, more water is taken out than replaced

“After three years of parched conditions,” say Peter Brabeck-Letmathe and Carl Ganter, “water levels in nearly all monitoring wells in [California] are at record lows. Many have dropped more than 15 metres in the last year alone. Even in years with normal rainfall, more water is taken out than replaced, and hundreds of families in the Central Valley lost running water to their homes last summer when the aquifer level fell below the reach of their wells.”

In the short term, to avoid a water crisis we’ll need to fix pipes and conserve water through changes in usage habits. But that only delays the inevitable.

Considering that the Earth’s surface is 71% water, desalination has often been proposed as a solution. But the technology, which uses reverse osmosis to force seawater through polymer membranes to remove salt particles, is expensive, potentially harmful to aquatic life and energy intensive. A typical desalination plant can consume 6kWh of electricity to produce one cubic metre of fresh water.

Inside the Sorek water desalination plant
The Sorek desalination plant in Israel uses reverse osmosis in these tubes to remove salt from seawater.

Desperation for more water means that it’s a price some are willing to pay. In Santa Barbara, for example, officials are resurrecting a mothballed desalination plant as the city’s reservoir, river and ground water supplies diminish. According to the LA Times, the plant was constructed in the 1990s when the area was so desperate for water, people “even floated the notion of towing icebergs down the coast from Alaska to provide some relief.”

A more viable option than iceberg-towing

Newer technology hopes to make desalination a more viable option than iceberg-towing. MIT Technology Review reports that the $500 million Sorek plant near Tel Aviv, Israel can produce 627,000 cubic meters of water on a daily basis for a cost of around $0.58 (38 pence) per cubic metre. That’s lower than any other desalination plant currently in operation and Sorek manages this through reduced energy consumption and more efficient pumps/recovery systems.

“Sorek sets significant new industry benchmarks in desalination technology, capacity and water cost,” says IDE Technologies, the company who built the Israeli plant. “It provides clean, potable water for over 1.5 million people, comprising 20% of the municipal water demand in Israel, thus alleviating the country’s potable water shortage while minimizing the impact on terrestrial and marine environments.”

Aerial view of the Sorek desalination plant
The Sorek desalination plant is the largest and most advanced of its kind, producing up to 20% of Israel’s drinking water.

The next challenge is to improve the water purification process, reducing inefficiencies further. Researchers believe that carbon nanotube membranes could provide this future solution, as gaps between carbon atoms will let water molecules through but absorb larger sodium and chloride ions.

Tie this technology together with a system devised by Philip Davies at Aston University that uses renewable energy to combat high energy consumption and desalination could become a viable method of water production as a water crisis looms.

Top image, copyright: irina d’elena/Shutterstock

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