Indian Journal of Geo-Marine Sciences Vol. 44(12), December 2015, pp. 1867-1873 Assessment of salinity gradient power in Bahmanshir River estuary based on reverse electrodialysis method Abdolreza Sabetahd Jahromi 1 , Kamran Lari 2 , Ali Morsali 3 , Abasali Aliakbari Bidokhti 4 , Mohammad jaafar Soltanian fard 5 1 Department of physical oceanography, college of marine Science and technology, Science and Research Branch, Islamic Azad University, Tehran, Iran, 2 Department of physical oceanography, college of marine Science and technology, Tehran North Branch, Islamic Azad University, Tehran, Iran, 3 Department of Chemistry, college of Science, Tarbiat Modares University, Tehran, Iran, 4 Geophysics Institute, Tehran University, Tehran, Iran, 5 Department of Chemistry, college of Chemical Science, Firoozabad Branch, Islamic Azad University, Firoozabad, Fars, Iran, [E.mail: ar.sabetahd@yahoo.com ; kameran.lari@yahoo.com ; morsali_a@modares.ac.ir ; bidokhti@ut.ac.ir ; mohammadjaafar_soltanian@yahoo.com ] Received 21 April 2014; revised 14 October 2014 In this study, the salinity of Bahmanshire river water was analyzed using physical parameters measured in two hydrometric stations. Then, comparing the salinity of Bahmanshire River with that of the Persian Gulf, the recoverable electrical energy was analyzed theoretically. The results showed that khorramshahr station yielded more extractable energy than Tarah Bokhah one. [Keywords: Renewable energy, Salinity gradient, Reverse electrodialysis, Persian Gulf, Bahmanshire River, Estuary] Introduction One of the serious challenges in power industry is its severe dependence on fossil energy resources. In Iran, 95% of electrical energy is generated by fossil fuels (Table 1), whilst there are debates on the lifetime of major energy resources. In addition, the dependence of economic development on energy and growing trend of demand for electrical power as well as strict international rules on environmental issues indicate the importance of identifying and accessing renewable energy resources 1 . Table 1— Power generated by different power plants in Iran 1 Contribution (%) Power generation capacity (×10 6 kWh) Power plant type 39.9 95901 Steam plants 24.5 58716 Gas plants 30.3 72749 Hybrid cycle plants 5.0 12058 Water power plants 0.1 281 Diesel, wind and renewable energy 0.2 359 Nuclear plants 100 240064 Total The present work studies salinity gradient power (SGP) that naturally exists in Bahmanshire River. The energy recoverable by reverse electrodialysis (RED) will be theoretically analyzed. RED is the reverse of common electrodialysis (ED) process. Electrodialysis (ED) was discovered by Maigrot and Sabates in 1890 2 . Manecke suggested energy storage by electrodialysis method in 1954 3 . He found that electrical energy can be reused via inverse operation of membrane accumulator. Pattle was first one who mixed river and sea water in a hydroelectric pile and cited RED as a power resource 4, 5 . In general, systems used in ED and RED processes are similar. Figure 1 shows a single unit RED system. To learn more about this process, RED operation is described below.