Renewable Energy Technologies Make Desalination More Sustainable

In some of the driest regions of the world, desalination will become an increasingly important source of fresh, potable water. However, the process of separating salt and water is an expensive and energy-intensive one that often includes chemical treatments, thermal distillation and filtration by reverse osmosis.

Some companies are working to offer more sustainable alternatives, though. The New York Times reports that Masdar, an Abu Dhabi-based renewable energy company, is focused on finding ways to desalinate sea water using clean energy such as solar power.

The Middle East and Northern Africa regions are home to 6.3 percent of the world's population but harbor only 1.4 percent of the world's drinkable water. The Gulf in particular is very water-scarce. Desalination uses seven percent of the world's energy, using up oil and gas to produce a cheap commodity instead of generating export revenue.

The company is receiving financial support from Abu Dhabi's investment arm Mubadala and has plans to build three pilot plants over the next three to four years where new technologies will tested to assess their potential for large scale use. These include forward osmosis (a variant of semi-permeable membrane filtration technology known), electrodialysis deionization, membrane distillation and low-temperature distillation. The program will also look at ways to increase the energy efficiency of established technologies such as reverse osmosis.

Meanwhile, also in the UAE, Acciona Agua is leading a consortium that will build an energy-efficient desalination plant on the shores of Fukairah in the next two and half years. The plant is part of an extension to the Fujairah F1 plant in Al Qidfa. It is aiming for a specific energy consumption of 3.7 kilowatt hours (kWh) for every cubic meter of water produced. The usual requirement in Abu Dhabi is between four and six kWh per cubic metre.

Elsewhere, Energy Recovery, a California-based company, has created an energy-efficient desalination technology called Pressure Exchanger, a ceramic pump based on a rotary positive displacement pump. It takes all the water that doesn't go through a membrane (60 percent) and recovers all the pressure and energy that it stores. In an interview to Energy Refuge, CEO Thomas Rooney said about the technique: "You can let it go back to sea and lose all the potential energy, or try to recover it. We circulate the energy back in."

Image credit: Rainharvest