Siemens turns seawater into drinking water for half the energy

Having completed early tests of an energy-saving method for turning saltwater into clean drinking water, Siemens is preparing to take its technology to the product development phase.

The technology, which uses half as much energy as other desalination processes, was tested at a demonstration plant built in Singapore. Siemens now plans to set up a full-scale system in cooperation with Singapore’s national water agency PUB by 2013.

Singapore, an island nation, is one of many parts of the world in which seawater is becoming an increasingly important source of drinking water. However, desalination is an extremely energy-intensive process.

“Our new technology marks a revolution in seawater desalination,” said Ruediger Knauf, vice president of Siemens Water Technologies’ Global R&D. “The results of our pilot facility show that the new process not only functions in the laboratory but also on a larger scale in the field. Because of its high energy efficiency and thus good CO2 footprint, electrochemical seawater desalination can play a major role in regions suffering from freshwater shortages.”

Instead of using reverse osmosis, which requires high-pressure pumps to force water through semi-permeable membranes, the Siemens process relies on electrochemical desalination. The process combines electrodialysis (ED) and continuous electrodeionization (CEDI), both applying an electric field to draw sodium and chloride ions across ion exchange membranes and out of the water. As the water itself does not have to pass through the membranes, the process can be run at low pressure, and hence low power consumption.