Blue Energy

Researchers in the Netherlands recently opened a facility to test the commercial viability of a largely untapped renewable energy resource. The facility will utilize the principle of reverse electrodialysis (RED) to take advantage of the natural difference in salt concentration that occurs wherever fresh water and salt water mix.

The technology employs two ion selective membranes – one for positively charged sodium ions and one for negatively charged calcium ions. As the ions are separated, they produce a battery. By placing thousands of these membranes between two electrodes, significant amounts of energy can be produced.

It has been estimated that one cubic meter per second of fresh water and sea water will produce 1 MW of power per year. That translates into a worldwide potential of 1.4 to 2.6 terrawatts of electricity that could be generated from rivers flowing into the sea. The same principles could also be applied to saline waste streams from industrial facilities.