Socio-economic & technical assessment of photovoltaic powered membrane desalination processes for India

Fresh water crisis is evident in many parts of India, varying in scale and intensity at different times of the year. About seven states are underlain by brackish ground water affecting 42 million people. 25% population of India resides along the coast having easy access to seawater. Hence, these saline water resources can be exploited to meet their water requirements. Desalination technologies create new sources of fresh water from seawater or brackish water, but they do require energy. This paper addresses the socio-economic and technical feasibility of powering membrane desalination technologies with photovoltaic (PV) systems in regions which have mixed advantage of high solar potential and disadvantage of presence of saline water. A database of Indian population dependence on saline water, its regional solar potential and present state of desalination have been compiled. Technical aspects of reverse osmosis (RO) and electrodialysis (ED) membrane desalination processes powered by PV are addressed and desalinated water cost, obtained through PV-RO and PV-ED processes, are compared with diesel powered RO and ED processes respectively for a plant capacity of 50 m3/day over a 20 year working life of the plant. The technology will augment fresh water requirements of India and contribute to its sustainable development.

Research Highlights
► A database of Indian population dependence on saline water, its regional solar potential and present state of desalination have been compiled.
► Technical aspects of reverse osmosis (RO) and electrodialysis (ED) membrane desalination processes powered by PV are addressed and desalinated water cost, obtained through PV-RO and PV-ED processes, are compared with diesel powered RO and ED processes respectively over a 20 year working life of the plant.
► A comparative analysis of PV module system and diesel generator system on varying the salt water concentration and plant capacities has been conducted.
► In order to resolve the shortage of pure water, desalination plants of relatively small to medium capacity, as discussed in the present paper, appear to be the most advantageous, both economically (reduced capital) and technically (minimum construction time, local availability of manpower and raw materials, simple operation and less maintenance).