Justification, design, and analysis of a village-scale photovoltaic-powered electrodialysis reversal system for rural India

This paper presents the merits of village-scale photovoltaic (PV) powered electrodialysis reversal (EDR) systems for rural India and the design and analysis of such a system built by the authors with planned testing to be completed in March 2015 in Alamogordo, New Mexico. The requirements for the system include daily water output of 6-15 m³/day (enough potable water for the average village size of 2,000-5,000 people), removal of dissolved salts in addition to biological contaminants, photovoltaic power source, recovery ratio of greater than 85% and appropriate maintenance and service scheme. At present, most village-scale desalination systems use reverse osmosis (RO), however the managing NGOs have found the systems to be cost prohibitive in off-grid locations. EDR has the potential to be more cost effective than currently installed village-scale RO systems in off-grid locations due to the lower specific energy consumption of EDR versus RO at high recovery ratios. This leads to lower power system cost and overall capital expense. The system developed in this study is designed to validate whether the system requirements can be met in terms of recovery ratio, product water quality, specific energy consumption, and expected capital cost. The system is designed to desalinate 3600 ppm brackish groundwater to 350 ppm at a rate of 1.6 m³/hour and a recovery of 92%. This paper reviews the scope of the market for village scale desalination, existing groundwater salinity levels, and presents the design methodology and resulting system parameters for a village-scale PV-EDR field trial.