Skip navigation

Tag Archives: seawater desalination

Brine dischage in Gulfchemical usage in desalinationDesal capacityDesalination capacity in the worldsalinity levels in Gulf regionwater cycle

Water and energy are two critical issues that will decide the future of humanity on the planet earth. They determine the security of a nation and that is why there is an increasing competition among nations to achieve self-sufficiency in fresh water and clean energy. But these issues are global issues and we need collective global solutions. In a globalised world the carbon emission of one nation or the effluent discharged into the sea from a desalination plant changes the climate of the planet and affects the entire humanity. It is not just a problem of one nation but a problem of the world. The rich and powerful nations should not pollute the earth, air and sea indiscriminately, hoping to achieve self-sufficiency for themselves at the cost of other nations.  It is very short-sighted policy. Such policies are doomed to fail over a time. Next generation will pay the price for such policies. Industrialised countries and oil rich countries should spend their resources on research and development than on weapons and invent new and creative solutions to address some of the global problems such as energy and water. With increasing population and industrialisation the demand for energy and water is increasing exponentially. But the resources are finite. It is essential that we conserve them, use them efficiently and recycle them wherever possible so that humanity can survive with dignity and in peace. It is possible only by innovation that follows ‘Nature’s path.

The earth’s climate is changing rapidly with unpredictable consequences .Many of us are witnessing  for the first time in our lives unusual weather patterns such as  draughts, flash flooding,  unprecedented   snow falls, bush fires, disease and deaths. Although we consider them as natural phenomena there is an increasing intensity and frequency that tells us a different story. They are human induced and we human beings cause these unprecedented events. When scientists point out human beings cause the globe to warm there were scepticism. We never believed we were capable of changing the entire weather system of the globe.

We underestimate our actions. By simply discharging effluent from our desalination plants into the sea, can we change the salinity of the ocean or by burning coal can we change the climate of the world? The answer is “Yes” according to science. Small and incremental pollution we cause to our air and water in everyday life have dramatic effects because we disturb the equilibrium of the Nature. In order to restore the equilibrium, Nature is forced to act by changing the climate whether we like it or not.

Nature always maintains“equilibrium” that maintains perfect balance and harmony in the world. If any slight changes are made in the equilibrium by human beings then Nature will make sure such changes are countered by a corresponding change that will restore the equilibrium. This is a natural phenomenon. The changes we cause may be small or incremental but the cumulative effect of such changes spanning hundreds of years will affect the equilibrium dramatically.

We depend on fossil fuels for our energy needs. These fossils were buried by Nature millions of years ago. But we dig deep into the earth, bring them to surface and use them to generate power, run our cars and heat our homes. Our appetite for fossil fuels increased exponentially as our population grew. We emitted Carbon into the atmosphere from burning fossil fuels for hundreds of years without many consequences. But the emissions have reached a limit that causes a shift in Nature’s equilibrium and Nature will certainly act to counter this shift and the consequences are changes in our weather system that we are now witnessing. The only way to curtail further Carbon emission into the atmosphere is to capture the current Carbon emissions and convert them into a fuel so that we can recycle them for further power generations without adding fresh fossil fuel into the system while meeting our energy demands.

We can convert Carbon emissions into a synthetic natural gas (SNG) by using Hydrogen derived from water. That is why I always believe ‘Water and energy are two sides of the same coin’. But cost of Hydrogen generation from water will be high and that is the price we will have to pay to compensate the changing climate. Sooner we do better will be the outcome for the world.

In other word the cost of energy will certainly go up whether we price the Carbon by way of trading or impose Carbon tax or pay incentives for renewable energy or spend several billions of dollars for an innovative technology. There is no short cut. This is the reality of the situation. It will be very difficult for politicians to sell this concept to the public especially during election times but they will have no choice.

Similarly serious shortage for fresh water in many parts of the world will force nations to desalinate seawater to meet their growing demand. Saudi Arabia one of the largest producers of desalinated water in the world is still planning for the highest capacity of 600,000m3/day. This plant will discharge almost 600,000 m3/day of effluent back into the sea with more than double the salinity of seawater. Over a time the salinity of seawater in the Gulf region has increased to almost 40% higher than it was a decade ago. What it means is their recovery of fresh water by desalination will decrease or their energy requirement will further increase. Any increase in salinity will further increase the fossil fuel consumption (which they have in plenty) will increase the Carbon emission. It is a vicious cycle and the entire world will have to pay the price for such consequences. Small island nations in pacific will bear the brunt of such consequences by inundation of seawater or they will simply disappear into the vast ocean. Recent study by NASA has clearly demonstrated the relationship between the increasing salinity of seawater and the climate change.

According to Amber Jenkins Global Climate Change Jet Propulsion Laboratory:

“We know that average sea levels have risen over the past century, and that global warming is to blame. But what is climate change doing to the saltness, or salinity, of our oceans? This is an important question because big shifts in salinity could be a warning that more severe droughts and floods are on their way, or even that global warming is speeding up...

Now, new research coming out of the United Kingdom (U.K.) suggests that the amount of salt in seawater is varying in direct response to man-made climate change.  Working with colleagues to sift through data collected over the past 50 years, Peter Stott, head of climate monitoring and attribution at the Met Office in Exeter, England, studied whether or not human-induced climate change could be responsible for rises in salinity that have been recorded in the subtropical regions of the Atlantic Ocean, areas at latitudes immediately north and south of Earth’s tropics. By comparing the data to climate models that correct for naturally occurring salinity variations in the ocean, Stott has found that man-made global warming — over and above any possible natural sources of global warming, such as carbon dioxide given off by volcanoes or increases in the heat output of the sun — may be responsible for making parts of the North Atlantic Ocean more salty.

Salinity levels are important for two reasons. First, along with temperature, they directly affect seawater density (salty water is denser than freshwater) and therefore the circulation of ocean currents from the tropics to the poles. These currents control how heat is carried within the oceans and ultimately regulate the world’s climate. Second, sea surface salinity is intimately linked to Earth’s overall water cycle and to how much freshwater leaves and enters the oceans through evaporation and precipitation. Measuring salinity is one way to probe the water cycle in greater detail.”

It is absolutely clear that the way we generate power from fossil fuels and the water we generate from desalination of seawater  cannot be continued as business as usual but requires an innovation. New technologies to generate power without emitting Carbon into the atmosphere and generating fresh water from seawater without dumping the highly saline effluent back into the sea will decide the future of our planet. Discharge of concentrated brine into sea will wipe out the entire fish population in the region. The consequences are dire. Oil rich countries should spend their riches on Research and Developments to find innovative ways of desalinating seawater instead of investing massively on decades old technologies and changing the chemistry of the ocean and the climate forever.

 

We have used Hydrocarbon as the source of fuel for our power generation and transportation since industrial revolution. It has resulted in increasing level of man-made Carbon into the atmosphere; and according to the scientists, the level of carbon has reached an unsustainable level and any further emission into the atmosphere will bring catastrophic consequences by way of climate change. We have already saw many natural disasters in a short of span of time. Though there is no direct link established between carbon level in the atmosphere and the global warming, there is certainly enough evidence towards increase in the frequency of natural disasters and increase in the global and ocean temeperatures.We have also seen that Hydrogen is a potential candidate as a source of future energy that can effectively substitute hydrocarbons such as Naphtha or Gasoline. However, hydrogen generation from water using electrolysis is energy intensive and the source of such energy can come only from a renewable source such as solar and wind. Another issue with electrolysis of water for Hydrogen generation is the quality of water used. The quality of water used for electrolysis is high, meeting ASTM Type I Deionized Water preferred, < 0.1 micro Siemen/cm (> 10 megOhm-cm).

A unique desalination technology has been developed by an Australian company to generate on site Hydrogen directly from seawater. In conventional seawater desalination technology using reverse osmosis process only 30-40% of fresh water is recovered as potable water with TDS less than 500 ppm as per WHO standard. The balance highly saline concentrate with TDS above 65,000 ppm is discharged back into the sea which is detrimental to the ocean’s marine life. More and more sweater desalination plants are set up all over the world to mitigate drinking water shortage. This conventional desalination is not only highly inefficient but also causes enormous damage to the marine environment.

The technology developed by the above company will be able to recover almost 75% of fresh water from seawater and also able to convert the concentrate into Caustic soda lye with Hydrogen and Chlorine as by-products by electrolysis. The discharge into the sea is drastically reduced to less than 20% with no toxic chemicals. This technology has a potential to revolutionize the salt and caustic soda industries in the future. Caustic soda is a key raw material for a number of chemical industries including PVC.Conventionally, Caustic soda plants all over the world depends on solar salt for their production of Caustic soda.Hydrogne and Chlorine are by-products.Chlrine is used for the production of PVC (poly vinyl chloride) and Hydrogen is used as a fuel.

In the newly developed technology, the seawater is not only purified from other contaminants such as Calcium, Magnesium and Sulfate ions present in the seawater but also concentrate the seawater almost to a saturation point so that it can be readily used to generate Hydrogen on site. The process is very efficient and commercially attractive because it can recover four valuable products namely, drinking water, Caustic soda lye, Chlorine and Hydrogen. The generated Hydrogen can be used directly in a Fuel cell to generate power to run the electrolysis. This process is very ideal for Caustic soda plants that are now located on seashore. This process can solve drinking water problems around the world because potable water becomes an industrial product. The concentrated seawater can also be converted in a salt by crystallization for food and pharmaceutical applications. There is a growing gap between supply and demand of salt production and most of the chemical industries are depending upon the salt from solar pans.

Another potential advantage with this technology is to use wind power to desalinate the water. Both wind power and Hydrogen will form a clean energy mix. It is a win situation for both water industry and the environment as well as for the salt and chemical industries. In conventional salt production, thousands of hectares of land are used to produce few hundred tons of low quality salt with a year-long production schedule. There is a mis match between the demand for salt by large Caustic soda plants and supply from primitive methods of solar production by solar evaporation contaminating cultivable lands.

The above case is an example of how clean energy technologies can change water, salt and chemical industries and also generate clean power economically, competing with centralized power plants fuelled with hydrocarbons. Innovative technologies can solve problems of water shortage, greenhouse gases, global warming, and environmental pollution not only economically but also environmental friendly way. Industries involved in seawater desalination, salt production, chemical industries such as Caustic soda, Soda ash and PVC interested to learn more on this new technology can write directly to this blog address for further information.

%d bloggers like this: