Mmmmm delicious cold seawater
We’re surrounded by the stuff – 326 million trillion gallons of the stuff. It’s what makes this planet blue. But sea water is too salty for human consumption, so it’s a top priority for innovators globally to find a cheap and fast way to make it drinkable.
Here’s the technical stuff:
Seawater contains significant amounts of dissolved salts. In this case, the concentration is the amount (by weight) of salt in water, as expressed in “parts per million” (ppm). If water has a concentration of 10,000 ppm of dissolved salts, then one percent of the weight of the water comes from dissolved salts.
Here are our parameters for saline water:
Fresh water – Less than 1,000 ppm
Slightly saline water – From 1,000 ppm to 3,000 ppm
Moderately saline water – From 3,000 ppm to 10,000 ppm
Highly saline water – From 10,000 ppm to 35,000 ppm
Ocean water contains about 35,000 ppm of salt.
The worldwide need for fresh water
The scarcity of fresh water resources and the need for additional water supplies is already critical in many arid regions of the world and will be increasingly important in the future. It is very likely that the water issue will be considered, like fossil energy resources, to be one of the determining factors of world stability, will become currency to some, and an excuse for war with others.
World-wide availability of renewable energies and the availability of mature technologies now make it possible for the marriage of desalination plants with renewable energy production processes to produce fresh water in a sustainable and environmentally friendly scheme.
The Water Cycle
In nature, the sun causes water to evaporate from surface sources such as lakes, oceans, and streams. The water vapor eventually comes in contact with cooler air, where it re-condenses to form dew or rain. This process can be imitated artificially, and more rapidly than in nature, using alternative sources of heating and cooling. Solar desalination is used by nature to produce rain which is the main source of fresh water on earth. All new man-made distillation systems are becoming non-carbon copies on a small scale of this natural process. Desalination/Distillation is one of mankind’s earliest forms of water treatment.
More desal facts
In 2010 there were about 13,500 desalination plants around the world in 120 countries. They produce some 15 million m3/day of freshwater, which is less than 1% of total world consumption. The most important users of desalinated water are in the Middle East, (mainly Saudi Arabia, Kuwait, the United Arab Emirates, Qatar and Bahrain), which use about 70% of worldwide capacity; and in North Africa (mainly Libya and Algeria), which uses about 6% of worldwide capacity. Among industrialized countries, the United States is one of the most important users of desalinated water (6.5%), specially in California and parts of Florida.
See ‘Water crisis to water surplus?’