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Showing posts with label PVC. Show all posts
Showing posts with label PVC. Show all posts

Monday, July 16, 2012

Hydrogen from seawater for Fuelcell

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 witnessed 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 onsite 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 onsite. 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 currently 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 manner. 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.

Friday, June 8, 2012

Green Chemistry and Clean technologies

Chemistry has revolutionized human life and it has affected each and every one of us in some way or other for the past several decades. We were happily using these chemicals in our everyday life without really understanding their side effects.Individuls and companies who invented and commercialized chemical products were keen to offer end products to consumers often without explaining the side effects of such chemicals.They themselves were not fully aware of long term consequences of such chemicals. Classical examples are Chlorine and its derivatives. Chlorine is a common chemical that is used even today in many countries to disinfect drinking water in water treatment plants. Their usage is sill continued though they found that Haloalkanes, which are formed by the action of Chlorine on decayed organic leaves in water storage, causes cancer (carcinogenic). DDT is another chemical that was used widely as a pesticide, known as “atom bomb of pesticides”, until their side effects proved deadly for human beings and to the environment. It was officially banned in USA in 1972 by EPA, though it is still continued in some third world countries. Bleaching powder in another example of powder disinfectant ( a popular form of disinfectant used on roads in India when prominent political leaders visit municipalities; though they are only chalk powder with no traces of residual Chlorine). A whole range of dyes known as coal tar dyes derived from coal were used in many applications including ‘food colors’, later substituted by petroleum based organic chemicals. These ‘food colors’ are now substituted with ‘natural organic colors’ such as vegetable colors derived from vegetables and fruits. Industrial chemicals, both organic and inorganic have caused serious environmental damages all over the world for several decades, but Governments, companies and EPA did not realize the deadly consequences of some these chemicals for a long time. The ‘Bhopal Gas tragedy’ in India is one such grim reminder of such consequences. Chemicals are not natural products even though one can separate them into various organic chemical molecules but some of the consequences of such separation and usage are not fully understood. Many natural herbs have outstanding medicinal values and when consumed in a Natural form, it has absolutely no side effects and they show tremendous therapeutic values. But when you isolate certain molecules from such herbs (Alkaloids) and used as a drug, they can cure a disease but at the same time, they create many side effects. Nature offers such drugs in a diluted form that is quite compatible to human beings. One such example is ‘Vinblastine’ and “Vincristine’, anti-cancer drugs derived from a herb called ‘vinca rosea’. Of late there is awareness among companies, people and Governments about Green technologies that can help protect the environment. Greenhouse gas and global warming is one such issue. When Petrol or Diesel, an organic chemical known as Hydrocarbon is burnt, it not only generates power but also emits greenhouse gases such as Carbon dioxide and oxides of Nitrogen, that cause globe to warm. We were happily burning away such fossil fuels until scientists raised an issue on emission of ‘greenhouse gases’ in recent past. When we deal with chemicals and chemical reactions, the molecule is transformed into a new molecule and often such reaction cannot be reversed.It is not a physical change but a chemical change. When we convert water into steam, we can get back water by condensing steam; but when you convert Chlorine into PVC (Poly vinyl chloride) plastic, there are environmental consequences and reversing PVC into Chlorine gas in not easy, though it is technically possible with environmental consequences. One has to observe and learn from Nature what is good and what is bad when developing a new technology, because such development will not only affect the environment but also many generations to come. When Nature teaches how to turn sugar into Alcohol by fermentation using air borne microorganisms, we should follow Nature to make alcohol. We know how to turn Alcohol into PVC, but we do not know how to make biodegradable PVC from Alcohol. Companies call it ‘Green Chemistry’, but not until we can make a biodegradable PVC. Human knowledge is imperfect and we can only learn ‘Green chemistry and Clean Technologies’ from Nature and not by deviating from the path of Nature.