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Tag Archives: Sodium hydroxide

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.

Sodium chloride commonly known as ‘ common salt ‘ is a basic  raw material for the production of a range of chemicals including Caustic soda and Soda ash. The cost salt has been recently increasing steadily due to wide demand supply gap all over the world. This in turn has increased the cost of all other chemicals derived from salt and this situation is expected to continue in future.

Salt industry has been traditionally using a ‘solar evaporation’, an age-old technique from antiquity. The technology involves pumping of seawater on large area of arid land and allowed to evaporate as the concentration of salt increases. The brine then passes on through the various ponds, with the sodium chloride content rising from 2% to 25%. This increasing salinity gives the ponds a distinctive pink color, as algae in strongly saline solutions produce a red pigment called haematochrome. The Red Sea is red for the same reason.

The saturated brine is pumped to smaller ponds where nature continues its work of evaporation. Once the volume has been reduced to 10.2% of the original, any further concentration results in the deposition of sodium chloride. From September to February more brine is added until at least 25 mm of salt has settled and it is time for harvesting. The brine remaining (called “bittern”) is a saturated solution of NaCl, with the other salts present at concentrations well below saturation. This is pumped out to sea just before the harvest is gathered, as these ions would contaminate the salt if all the water were evaporated off. For four to six weeks beginning in early March, mechanical harvesters scoop up the crystallized salt and load it on to trucks that shuttle back and forth across the ponds to the washer. In the two washing plants the salt is washed in clean saturated brine, where the other salts, present as impurities, dissolve. From their hundreds of tones of clean washed salt are discharged daily on to the stacks for storage – up to 10,000 tons per day. During winter no more salt is recovered, but the plant continues its regular work of processing and bagging the stockpiled salt.

But this raw salt has number of impurities such as Calcium, Magnesium and Sulfate ions which are harmful for the production of further chemicals. Though the cost of producing salt is cheaper by solar evaporation, the cost of purifying salt from above impurities and making suitable brine for chemical production is expensive .The cost of salt used in chemical processing industries after transportation and purification increase to whopping $ 200 and above. Many Asian countries such as Japan, South Korea, China, Taiwan and Indonesia are major importers of salt. The salt import by the above importers in Asia pacific region between 2000 and 2009 has increased by 6 million tonnes, equal to 40% or 4.6% per annum.In four years between 2005 and 2009, the price of salt increased  by US$25/Mt, equal to 83% or 16% per annum.The average price of imported salt varies between US$40 to $47/Mt. (Ref: Salt partners).

Erratic weather patterns, sea level rise, Tsunami, inundation, flooding and unseasonal rains have hampered salt production all over the world. The chemical industries are facing an uncertain future and unpredictable pricing of salt. Prolonged winter in Europe and US and other parts of the world have pushed the demand for salt for de-icing. India is the third largest and cheapest producer of salt in the world with lowest labor cost. But even in India, the prices of salt have gone up recently from Rs.600 to Rs.1000/Mt.

An Australian company has developed and patented an innovative technology to solve the above problems. The company uses membrane technology to produce Sodium chloride brine directly from seawater suitable for all chemical products in the downstream. This novel technology separates seawater into salt and drinking water, after all seawater has about 95% pure water. It can solve the problems of many mining companies in Australia who need Caustic soda as well as water for their processing.India can certainly adopt this technology because shrinking coastal land for solar evaporation will become  scarcer in the future.

How many of us think  about the Sun and Sea, when you drink ‘Mineral water’ from that ‘PVC bottle’; or think about the PVC cables that transmit power to your home; or  eat  meal with a pinch of salt or bicarbonate; or when your municipal water treatment plant use Chlorine to disinfect your drinking  water? All these come from sea water energized by sun’s light, day after day, for several decades.

Every year 111 billion liters of seawater are evaporated using solar energy to produce 1.1 billion liters of brine. The amount of solar energy required to produce this, is equal to 11 million tons of coal, valued at US$ 1.10 billion. The brine is then crystallized to produce 2 million tones of solar salt, the essential raw material for 18 basic inorganic chemicals, including soda ash. Soda ash and Caustic soda are two fundamentals raw materials to chemical industries, as steel is to the engineering industries. This above statistics applies to one single manufacturer, and there are hundreds of manufacturers around the world.

Sun and sea are two great gifts of Nature to mankind. But industries use three great resources  namely Sun, seawater and a vast stretch of land often free of cost. Companies convert  seawater  into  salt using sun’s energy, manufacture valuable chemicals, sell them with profits   and then dump all toxic wastes on the soil and discharge all the industrial effluents back into the sea, polluting not only the source of their raw materials but also killing thousands of marine species they call ‘sea’ as their home.

Governments and EPA (government agencies) turn a blind eye to such pollution and give them clearance year  after year in each country for several decades, because they depend on taxpayer’s money to run their Governments. The manufacturer use these natural resources free of cost or at a fraction of  cost and make huge profits to their shareholders and pay tax to the Government, to make sure  that Governments don’t interfere with their activities. What is really happening is few rich and powerful are able to exploit the natural resources and enrich themselves with the help of Governments  at the cost of earth, water and air, we human beings habitat.

This avaricious exploitation of Nature has driven not only human beings but many animals and species to extinction. Basic needs of life such as water and air are polluted, man-made waste are dumped indiscriminately on soil, polluting the earth and ground water. The plastic manufactured using Nature’s sun and sea water, are dumped back on earth as non-biodegradable pollutants. This is how we repay Nature.

Human beings have caused an irreversible damage to Nature in the name of science, technology and industrialization at the cost of future generation, while enriching few rich and powerful. The damage is irreversible,  because we are forced to continue the same path to avert any disruption to our growth story. As long as we value materials over morals and ethics, there is no future and Nature will eventually turn its back with vengeance. We value how much a person is worth financially  rather  than, what a person can contribute to the uplifting of human beings and Nature. This is the crux of all problems in the world, including the financial crisis we are currently facing. We created the monster called ‘materialism’ and the same monster is now destroying humanity.

 

 

 

Seawater is an inexhaustible source of Hydrogen but the cost of generating Hydrogen from seawater is much higher compared to normal tap water. The quality of water should have a minimum electric conductivity at 0.1 micro Siemens/cm for electrolysis. Even our tap water is not up to this purity and it requires further purification. The electric conductivity of seawater is about 54,000 micro Siemens/cm.The conductivity increases due to the presence of dissolved salts. But seawater can be desalinated using the process of distillation or by the process called ‘reverse osmosis’. In both the above processes, desalination requires a large input of energy in the form of thermal or electrical. Currently the source of such energy comes from fossil fuels, which is one the biggest emitters of greenhouse gas emission. Many countries in the Middle East have shortage of fresh water and most of these countries depend on desalination of seawater for their fresh water requirements. The cost of desalinated water varies from $ 1.00 to $ 1.75/m3 depending upon the capacity, site and the cost of energy. The fresh water for potable purpose normally has a TDS (Total dissolved solids) of 500ppm (parts per million) or less and this can further be lowered to a required level using reverse osmosis.

Currently Hydrogen is generated as a by-product on an industrial scale by electrolysis of saturated sodium chloride brine during the production of Caustic soda. Chlorine is another by-product in the above process. Most of Caustic soda manufacturers use Hydrogen as a fuel or for the production of Hydrochloric acid. But there is an opportunity in caustic soda plants to use Hydrogen to generate more electricity using PEM (Proto exchange membrane) Fuel cell suitable for their electrolysis. This will aid these industries to cut their energy consumption, which is one of the highest in Chemical industries.

Alternatively, offshore wind turbines can be installed to generate power for seawater desalination and Hydrogen production. Offshore wind turbines generate 50% more energy than onshore wind turbines. An integrated process to generate fresh water, Hydrogen using wind turbine is an interesting renewable energy application. The stored Hydrogen can used to generate electricity in remote islands where diesel is used as a fuel. Most of the island in Pacific use diesel predominantly for boat as well as for power generators at exorbitant costs. The wind velocity in such islands is good to generate cheap and clean electricity. For example, the island of PNG has a severe power shortage and it is well located near Coral Sea, which has one of the highest wind velocities in Pacific Ocean. An average wind velocity of 7mts/sec and above is an ideal place for wind turbines. Since these islands are small with less population, wind generated Hydrogen is an ideal solution for their power problems. They can also desalinate seawater to supply drinking water using wind generated power. In fact they can also use Hydrogen as a fuel for their boats and generate power for their cold storage for fisheries. International financial institutions and local banks should come forward to fund such projects instead of funding diesel boats and generators. These islands have pristine water and abundant fish and their main income is only tourism.

Sun, Sand and wind is an ideal combination to generate renewable power all round the year and for tourism industry. It is an opportunity these islands cannot afford to miss. The author is personally involved in a wind based Hydrogen solution for a small island in pacific. The people of this island welcome such projects because it guarantees them an uninterrupted supply of clean power and drinking water. Otherwise they have to sell most of fish catches in a nearby city to buy diesel and drinking water just to survive!

 

 

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