Many countries in the Middle East have been researchingdesalination — the process of removing salt from sea water so it is fit to drink. It makes sense especially in hot, dry countries where drinking water is not abundant. However, a team of European researchers from CORDISbelieve they can make the entire process even more efficient, by harnessing the region’s high levels of solar power to develop a high-efficiency and low-cost desalination system.
Currently the process of desalination is done through reverse osmosis (RO), where water is forced through a filtration membrane at high pressure. Substances, like salt, are then filtered out and are retained on the pressurized side of the membrane. Of course, energy is required for this high throughput process in order to pressurize the sea water through the system, and as a result it can be expensive and energy intensive.
The European team believe that the entire process can be made cheaper and more efficient by using a low-temperature Organic Rankine Cycle (ORC)system working in combination with solar cells. For those of you not in the know, an ORC is a thermodynamic cycle that is used to recover low-temperature (typically ‘waste’) heat and then convert it to another more useful form of energy such as electrical or mechanical energy.
By using this dual-pronged energy method, the desalination process would see solar cells supply the heat to the ORC, which would then in turn produce mechanical energy to pressurize the water. The European team have also developed an innovative stand-alone solar desalination system based on a low-temperature supercritical ORC with funding for the planned RO-Solar-Rankine project.
This system in theory eliminates the need for energy storage and exhibited higher efficiency translating to higher fresh water production rates. This entire process is cleaner, cheaper and gives countries faced with drought and dry conditions the ability to use their abundant solar energy to produce safe and fresh drinking water.
Images: iliveisland Pete Gibbons