‘Clean Energy and Water Technologies’ is now a social enterprise based in Melbourne, Australia. The purpose of this enterprise is to introduce a zero emission technology developed and patented by Ahilan Raman, the inventor of the technology. A 25 Mw demonstration plant will be installed to show case the above technology. This platform also used as a blog will publish articles relevant to Zero emission technologies for power and Zero liquid discharge technologies for water industries.
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Showing posts with label Seawater desalination. Show all posts
Showing posts with label Seawater desalination. Show all posts
Wednesday, April 19, 2017
CAPZ desalination technology uses only Sun,Sea and WInd !
Saturday, April 23, 2016
Parched land and thirsty farmers surrounded by ocean of water
Tuesday, August 25, 2015
Production of Caustic soda by desalination of sea water with fresh water as by-product
Wednesday, July 4, 2012
Energy,water and global warming
Wednesday, May 2, 2012
Water shortage drives global warming
Monday, March 26, 2012
The changing Chemistry of our oceans
Seawater is the largest source of fresh water as well as the source of Hydrogen energy.However; seawater cannot be used directly for these applications and it requires further treatment. Seawater contains a number of dissolved salts and the TDS, total dissolved solids, of seawater is about 35,000ppm (parts per million).The commonly used industrial desalination process is by RO (reverse osmosis) as well as by multistage flash distillation (MFD). Both these processes are energy intensive.RO process requires electrical energy and MFD requires thermal energy. Most of the countries in Persian Gulf use desalination process to convert seawater into drinking water as well as industrial water. These oil rich countries depend on the desalinated seawater as their main source of drinking water supply. In the desalination process by RO, the TDS level of seawater is reduced from 35,000ppm to 500ppm, meeting the WHO (World Health Organization) specifications for drinking purpose. The advantage with reverse osmosis process is it can remove even the smallest bacteria and virus, during the desalination. The water can further be disinfected by the injection of Chlorine before distributing for drinking purpose.
The majority of desalination plants use RO process because it is economical. There is a worldwide shortage for safe drinking water and more and more SWRO plants are coming up in various parts of the world. The technology of RO has advanced so much that the cost of desalinated seawater can compete with surface water in many parts of the world, especially in Gulf region where the energy cost is low. The rapid increase in population and industrial growth has created a greater demand for fresh water.
In conventional SWRO process, only 35-40% of fresh water is recovered and the balance 60-65% is discharged back into the sea as a highly saline brine, with TDS levels exceeding 65,000pm, almost double the salinity of seawater. Similarly most of the power plants located on sea coasts are using seawater for cooling purpose. In once through cooling system, the seawater is circulated into the power plant to condense steam in turbines and returned back to the sea. The temperature and salinity of the returning water into the sea is always higher than the intake water. Some oceanographers feel that such slow increase in salinity of seawater affects the temperature of the sea and the climate.
However, discharge of highly saline brine into the sea has become routine and EPA (Environmental and Pollution Authority) of various countries routinely approve such discharge, claiming it does not affect the marine life significantly. The environmental impact study conducted in one country is routinely followed by many countries and invariably conclude that such discharge has a very little or no impact to the environment. Human beings are concerned only with their environment and not with the marine environment where variety of marine species live. Our oceans have been heavily polluted from the time of industrial revolution by oil spills, toxic industrial effluent discharges, desalination and power plant discharges. The TDS levels of seawater in Gulf region has considerably increased in the past few decades. The TDS levels are about 50,000 ppm against conventional levels of 35,000PPM.The oceans are acidified by absorption of excess carbon dioxide from the atmosphere due to greenhouse gas emissions.
The power required to desalinate seawater is directly proportional to the osmotic pressure of seawater. The osmotic pressure increase as the TDS level increases, which in turn increases the energy consumption by desalination plants. A recent report from US government says that fresh water will become a serious issue after a decade and even wars may be waged between countries for the sake of fresh water. The human activities not only cause global warming but also changing the chemistry of our oceans. Steadily dwindling fish population is a clear indication of changing chemistry and biology of our oceans. In the absence of a proven scientific evidence to show that human beings cause these changes in the ocean, we will carry on our business as usual until we reach a point of no return.
If you add salt to the water, it will not boil at 100C at 1 atmospheric pressure but slightly at a higher temperature. It is high school physics. When the salinity of the ocean increases from 35,000ppm to 50,000ppm, does it not affect the evaporation of the sea, which condenses into a cloud and come back as a rain? Does it mean there will be less precipitation in the future? Even if the ocean is under constant circulation, the overall salinity level keeps increasing.
Wednesday, March 14, 2012
Wind energy-that can save islands
Wind is a potential source of renewable energy, especially for islands with an average wind velocity of 5mts/sec and above. Many islands in pacific ocean have some common problems like sea erosion, shortage of power and drinking water. These small islands with little population are fully depending on diesel fuel. In fact their life depends on diesel fuel and any increase in price significantly affects their daily life. Their main source of income is only by fishing and they live day to day.
I had a personal experience of visiting a small island off Port Moresby in Papua New Guinea. They call it Daugo Island or ‘Fisherman’s island’ with population of less than 700 people. It is about 4.5km wide and 2km long. It is a coral atoll pushed out of the sea. One can take stroll on the beach and it is one of the most beautiful experiences one can have. It gives a feeling that you are far away from the rest of the world. There is a small abandoned World War II Airfield. The people in the island do not have any electricity or drinking water, and most of them are fishing on small boats. Their boats are fuelled by diesel. They will go to nearby city of Port Moresby and sell their fish and with that money they will buy drinking water and diesel in cans, and return to the island. This is their daily life.
Such an island is an ideal location to set up a wind turbine and a small sea water desalination plant, that can easily solve their problem of water and power. The trade wind from the Coral Sea in the island of Papua New Guinea blows almost 7-8 months in a year and their wind velocity averages 7 mts/sec. Two wind turbines of each 250 kW capacity and a small seawater desalination SWRO plant of capacity 15,000lts/day will be sufficient to solve their problems. The desalination plant will consume about 4.5Kwhrs/m3 of water generated. About 2000 kwhrs/day of power can be supplied to the village, each family consuming about 2.85 kwhrs/day for 6 hours/day and also for the desalination plant. The system will generate surplus power.
Renewable wind energy is the best option for such islands to generate on-site power and also to desalinate seawater for supply of drinking water. With increasing global warming and sea level rising, these small island face seawater intrusion and inundation. Many islands are slowly disappearing into the vast sea. Moreover, these islands are the most vulnerable to the fluctuating diesels prices and they are walking on a tight rope.Industrialised countries with an average power consumption of several kilowatt hours per day are crying foul about rising energy cost while people in such small islands barely manage their food and shelter after paying for the diesel.
Recently the Government of Maldives conducted their cabinet ministers meeting under the sea, to showcase their plight due to sea level rise caused by global warming, to the rest of the world. Small islands can cry loud but their voice is muffled by roaring sea, while rest of the world carries on their business as usual.
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