Photovoltaic Reverse Osmosis and Electrodialysis

Abstract

Arid zones with less than a thousand inhabitants, remotely situated from large scale sources of power and potable water, are candidates for implementation of small scale Reverse Osmosis (RO) and Electrodialysis (ED) desalination processes using power supplied by Photovoltaic generation (PV). An ED/PV combination may only compete with an RO/PV combination for the desalination of unpolluted brackish water with low salinity. Energy and cost efficiencies depend on raw water quality, climate, accessible energy sources, number of consumers and demand per head, potentials for cogeneration (water and power) and hybridisation, industrial and educational environments. A selection of 10 plant configurations, including different processes and a wide range of capacities, is presented with typical design information and exemplary analysis of life cycle performance for specific sites. Results show that plant capacity should not be too small, power recovery should be provided wherever feasible, and any opportunity for cogeneration should be exploited. Hybridisation reduces levelised costs of electricity and water and increases the reliability of a minimum water supply under emergency conditions.