Dec 1, 2017
WATER "LISTED" IN STOCK MARKET?
Currently there is a huge certainty in the world: water is increasingly scarce. Who says are several scientists who conclude that the water will soon be far more precious than oil. At this rate, it won't take long to see water "listed" on Wall Street as the queen of stock quotes.
By HANS GRUBER
The desertification of many regions by natural causes, in many cases due to human intervention, has been to widen alarmingly. It rains increasingly less and when it rains it's on torrents, so that it destroys more than improve. The El Niño does not explain everything but gives a large contribution to the instability of the climate on the planet.
For government officials of many countries affected by periodic droughts, the only way to combat this lack goes "through fetch" water overboard. But as they recognize, desalination of sea water is still very restricted, because of the high operating costs and energy consumption.
Desalination, of brackish water so much as seawater, constitute, in certain circumstances, a solution to the shortage of water resources in some areas such as Arab countries, Spain, Canary Islands, the Balearic Islands, Andalusia, and Mediterranean coast or, in the case of Portugal, the island of Porto Santo in the Madeira Archipelago.
With the application of the latest technological advances – smaller investment and operating cost – reverse osmosis has imposed itself on desalination. Spain started its fight against drought by reverse osmosis of seawater with the construction, in charge of Degrémont, of the desalination installation of Lanzarote, in 1983, having built up to that date, since the decade of 1970, several reverse osmosis brackish water.
From the scientist's point of view, desalination is a human, technological and economic challenge of great interest due to the introduction of the concept of sustainability: the need to reduce the energy consumption of the premises, the emission of greenhouse gases, the production of electricity for the operation of the facilities, the use of reagents and the impact of the disposal of brines with a high content of salts on marine flora and fauna.
The solution to the problem could be obvious: take advantage of the abundance of sea water into the common use through desalination. The oceans cover more than 70% of the Earth's surface and contain 97% of water on the planet.
But recently, thanks to new technologies, the costs were reduced and desalination plants are being opened around the world.
Four-fifths of the world's desalination capacity are still produced by distillation processes in factories concentrated, mostly in Gulf countries. Saudi Arabia's capital, Riyadh, where practically never rains and where there are no rivers or lakes, answers alone for one-tenth of the world's production of desalinated water. Only one desalination plant, located East of the Arabian Peninsula, supplies Riyadh with a billion liters per day.
In typical modern systems of distillation, the salt water is heated when passing within tubes inside a chamber containing leftover steam from power plant – a kind of radiator in reverse. The warm seawater enters then depressurized chamber which reduces the temperature at which the water is boiling. So, water will "do everything" to evaporate. This principle is called electrolysis.
The second desalination technology, the inverse osmosis, was most popular the 1970's. In its essence, it is a filtering system. The pumped water is directed through a strong pressure against a membrane that retains the larger molecules of salt and leaves passage of the smaller molecules of clean water. However, the filters are efficient only in part, and the water needs to be pressurized and pass through the filters several times until it gets clean.
Both technologies require large amounts of energy. Until recently, to produce one cubic metre (1,000 litres) of water without salt would cost thousands of euros – about 100 times more than the cost of conventional water supply. But best filters manufacturing allowed to cut the costs of production of drinking water acceptable.