Fresh drinking water from the sea using solar
One of the main ways to obtain drinking water in hot, dry countries bordered to the sea is through desalination.
European researchers developed a high-efficiency and low-cost desalination technology by exploiting solar energy.
Solar desalination evaporation is used by nature to produce rain which is the main source of fresh water on earth. This new distillation system is a duplication on a small scale of this natural process.
Reverse osmosis: high costs
Reverse osmosis (RO) desalination is one of two traditional desalination methods. In RO, water is forced through a filtration membrane at high pressure. Undesired substances restricted by the size of filtration membrane pores are retained on the pressurized side of the membrane. A lot of energy (and high costs) is needed for initial pressurisation of the sea water.
One way to reduce both cost and energy consumption is to provide the mechanical energy required for RO using a low-temperature Organic Rankine Cycle (ORC) system in combination with solar cells.
Organic Rankine Cycle (ORC)
ORC is a thermodynamic cycle for recovering low-temperature (typically ‘waste’) heat and converting it to another more useful form of energy such as electrical or mechanical energy. Solar cells can supply the heat energy to the ORC, which then produces mechanical energy to pressurise the water.
Much attention has been given recently to the potential of supercritical fluids used in the ORC for optimized thermal efficiency in conversion of waste heat to electricity. European investigators delivered an innovative stand-alone solar desalination system based on a low-temperature supercritical ORC with funding for the RO-Solar-Rankine project.
The system eliminated the need for energy storage and exhibited higher efficiency translating to higher fresh water production rates.
Dr. Dimitris Manolakos
Agricultural University of Athens
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