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Energy Conversion using electrolytic concentration gradients

Published online by Cambridge University Press:  12 August 2015

Subramaniam Chittur K
Affiliation:
Materials Physics Department, VIT University, Vellore, TN, India. Endeavour Executive Fellow, College of Engineering and Science, Victoria University, Footscray, 3011,Victoria, Australia.
Aishwarya Chandran
Affiliation:
School of Mechanical and Building Sciences, VIT University, Vellore, TN, India.
Ashwini Khandelwal
Affiliation:
School of Mechanical and Building Sciences, VIT University, Vellore, TN, India.
Sivakumar A
Affiliation:
Environmental & Analytical Chemistry Division School of Advanced Sciences, VIT University, Vellore, TN, India.
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Abstract

Salinity gradient is an enormous source of clean energy. A process for potential generation from an ionic concentration gradient produced in single and multicell assembly is presented. The ionic gradient is created using a fuel cell type cell with a micro-porous ion exchange membrane, both anionic (AEM) and cationic (CEM). Various salinity gradients, Salt : Fresh, from 100 : 0 to 16000 : 0 was established using NaCl solution, in the electrode chambers. A potential of 20 mV/cm to 25 mV/cm can be realized at ambient temperatures and pressures for a bipolar AEM/CEM cell. The performance was optimized for various static and dynamic flow rates of the saline and fresh water. The cell performance can further be optimized for Membrane Electrode System (MES) morphology. A multicell unit was assembled and the results presented for various conditions like concentration gradients, flow rates and pressure. The thermodynamic and electrical efficiency needs to be evaluated for various gradients and flow rates. The relation with number of valance electrons/ ion and the potential generated changes for various dynamic condition of salinity. The higher the salinity gradient the larger is the potential generated. This is limited by the membrane characteristics. There exists a monotonic relation between the number of valence electron/ion/unit time and the potential generated up to about 16000 concentration. The membrane characteristics have been studied for optimal ion crossover for various gradients and flow. The graph between ln (gradient) versus Voltage provides insights into this process. This presents a very cost effective and clean process of energy conversion.

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Articles
Copyright
Copyright © Materials Research Society 2015 

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References

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