Drinking water from the sea using solar energy

July 31, 2012, CORDIS
Drinking water from the sea using solar energy
Credit: Thinkstock

One of the main ways to obtain drinking water in hot, dry countries surrounded by sea or ocean is through desalination. European researchers developed a high-efficiency and low-cost desalination technology by exploiting solar energy.

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 pressurised side of the membrane.

The only energy requirement is for initial pressurisation of the . Having said that, RO desalination is expensive and energy intensive due to the high throughput.

One way to reduce both cost and is to provide the required for RO using a low-temperature Organic Rankine Cycle (ORC) system in combination with .

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 optimised 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. Investigators also examined environmental as well as socioeconomic impacts of the new system and developed a strategy for market penetration.

Commercial implementation of the RO-SOLAR-Rankine system should enable climates such as those in the Mediterranean to exploit their abundant solar energy to produce freshwater from equally abundant saltwater.

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not rated yet Jul 31, 2012
Very expensive to buy and run.

Better would be a Superstill type desalinator, boil low temp water in a vaccum, that only needs a couple Deg F difference that can be supplied by a CSP Rankine engine. You'd not only get water but excess electricity.

Superstill patents should be over by now.
not rated yet Jul 31, 2012
What about if you simply focus sunlight from a wide area onto a shallow pool of sea water? It shouldn't take much to get that boiling away. Run that steam with a cheap fan into some shade and it will condense into pure water.

Just use gravity and sunlight to run the thing. Have the pool just below sea level and let the hot steam rise into a collection funnel.

High tides can flush the very salty water out with some sort-of salty water.
5 / 5 (2) Aug 01, 2012
People charging desal plants are expensive have not lived in areas where water shortages exist,like San Diego,the Central Coast of California,Baja California,Chile,Angola,Patagonia.
Ask these residents how much they pay for water.Then find out how the solar panels will pay for themselves over three decades.Also find out how much these citizens pay for such things as fresh fruits or vegetables arriving from over 200 miles away.

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