more about Desalination

About 884 million people in the world have no access to drinking water and many countries are either importing large quantities of food or supporting agricultural produce outside the country there by throwing food security outside the country. By 2025 this number will touch 4 billion. Can not imagine countries without water!! This is especially so with Gulf and MENA countries. As on today nearly 70 million tones worth of food grains are imported by these countries and the number is growing with exponential growth of population. Apparently this increase is related to lack of fresh water, groundwater as well as surface water in these countries. The rainfall is scanty and thus there is no source to recharge the aquifers. Many aquifers, to enhance the problem further, are trans-boundary in nature ad hence there is always war for water. As it has been said, the future war will be fought for water and not for power or territory. For example, the Saq Ram sandstone aquifer shared between Saudi Arabia and Jordan; the Umm er Raduma Eocene limestone aquifer shared between Saudi Arabia, Bahrain, Qatar, Kuwait and Oman. These are formation-waters and once the aquifer is emptied, no more water can be withdrawn from it. Here is a rat race!!! Wo will draw excess water to support their needs……not only for domestic but for irrigation purpose? According to the world Commission on Water, the global demand for fresh water will in crease by 50% over the next 30 years from the present consumption. Several Gulf and MENA countries have put in place desalination plants to meet fresh water demand for domestic and irrigation purposes. But utilizing fossil fuel based energy for desalination is not a viable and economic solution. Fresh water cost generated by desalination is very expensive and normal person can not afford to purchase it. Further, this process emits large CO2 that is detrimental to the world. In fact countries are fighting for stabilizing CO2 in the atmosphere. A viable technology has to be developed to generate fresh water from the ses through desalination using energy that is cost effective and renewable and green. The Gulf and MENA countries have huge untapped geothermal energy source(s) that can be utilized for desalination. Countries like, Saudi Arabia, Yemen, Eritrea, Kuwait, Libya, Egypt, Oman, Bahrain can use geothermal energy for desalination process there by controlling CO2 emissions from the desalination plants as well as from the power plants. Thus the future of the above countries depends on the availability of fresh water.
Agriculture, for example contributes 3% to the GDP of these countries, and because of lack of water, food imports in these countries have increased from 30 million tonnes in 2000 to greater than 70 million tonnes in 2010 and is poised to cross 100 million tonnes by 2020. For example, due to severe water scarcity, Saudi Arabia has increased its food imports from 1.9 in 2012 to 3.02 million in 2014. The annual per-capita water supply has drastically reduced from 3300 cubic metres in 1960 to less than 500 cubic metres. Not only for the Gulf and MENA countries, the entire world has to depend on sea for water. Geothermal energy is cost effective and by using this energy the cost of desalinated water could be brought down to < 3 cents / m3. Now that EGS is maturing with advancement made in drilling technology (plasma drilling will be the future technology) all the countries can be self-sufficient in food and water. Countries have to open and come out of its oil-gas glass house and start implementing new desalination process using geothermal energy. ( for more information read “ Desalination of Seawater using Geothermal Energy to Meet Future Fresh Water Demand of Saudi Arabia in Water Resources Management in J. Water Resources Management. At present 33 desalination plants are in operation in Saudi Arabia and more than this umber is operating in the Gulf countries around the Persian Gulf. With the government subsidy the cost of desalinated water is 3 US cents/ cubic metre which is far less than the average cost levied by the countries in the world which is 6 US$/cubic meter. If the government subsidy is removed, then the cost will be double the world average. Besides domestic and agricultural sectors, energy sector too needs fresh water. For example the world energy sector in 2010 consumed 583 billion cubic metres of water. According to the report published by the International Energy Agency, this consumption is expected to rise by 85% in 2030. Apparently there will be water crowding in the world and political conflicts since many aquifers and surface water bodies in the Gulf and MENA countries are trans-boundary in nature. The high water consumers in the power sector are fossil fuel based power plants and nuclear powered plants. Further water is required to irrigate crops to support biofuels based power plants. Solar photo voltaic (solar pv) panels too need water for cleaning and to maintain efficiency, especially in countries like Saudi Arabia. Desalination plants in many countries are working on solar based power, at 20% efficiency (maximum) and generating about 5000 cubic meter / day of fresh water. Water requirement for geothermal power plants are low and these power plants can generate fresh water as well. In Gulf countries, the most important support system that water resources can give to the country is in agricultural sector. The country needs water for agricultural activities, especially for growing staple food wheat and barley. Average per-capita consumption of wheat bread is 241 g per day. Saudi Arabia’s wheat consumption in MY 2013-2014 was 3.25 million metric tones. Due to shortage of fresh water for irrigation, the Govt. has banned wheat cultivation now and the imports have gone up to over 3 million metric tones from 1.9 million metric tones. This is disastrous to any country that puts its food security outside its boundary. Water stressed situation can be mitigated through developing its geothermal. Saudi Arabia, in fact all the countries around the Red Sea have copious geothermal resources, that are under developed, due to the active tectonic and magmatic activities of the Red Sea. The Harrats along the Arabian shield covered several active drainage systems and thus the paleochannels along the cost have supported high temperature hydrothermal systems with surface temperatures exceeding 90 °C with heat flow values exceeding 95 mW/m2. The bottom hole temperatures recorded in certain oil wells along the Red Sea coast and Suez Gulf varies from 120 to 260 °C. The Red Sea is currently is an active spreading ridge. It has been reported that the estimated power generating capacity of the hydrothermal systems associated with the Harrats is of the order of 173 x 106 kWh/ 1km2 of Harrat. Assuming that about 10 % of energy is extractable from the 90,000 km2 of the Harrats, an amount of 200 x 106 kWh of electric power can be generated from the hydrothermal systems associated with the Harrats. Besides the hydrothermal systems, the Arabian shield region hosts large volumes of high heat generating granites and the estimated power that can be generated from these granites using EGS technology is about 120 x 106 terawatt hour. This geothermal heat can be utilized for membrane distillation process (MD) while other desalination methods like multi effect distillation (MED), multi stage flash. Electro dialysis reversal (EDR) and vapour compression can utilize power generated from the geothermal resources along the Red Sea. The process involves circulation of hot water (temperature of about 60 °C) through a heat exchanger to heat seawater and decrease pressure to vaporise the water in a multi stage chamber. To generate large volume of desalinated water, the heated hot water is circulated to heat several chambers containing seawater through a method known as MED-MSF. In the case of geothermal systems where the temperatures are > 150 °C, power can be generated through binary technology that can be utilized by the desalination companies. About 80m3/h of fresh water can be generated through this process and 470 kwh of electricity can also be cogenerated. The advantage is here is to use multiple desalination methods to using geothermal power and the electricity cogenerated from this process. The estimated cost of desalinated water is about 1.5 euro/m3.