Integrated Pumped Hydro Reverse Osmosis systems

Ideal head height for pumped hydro energy storage/generation systems and reverse osmosis desalination plants coincide (500-700 m). Many drought stricken coastal regions have nearby mountains of sufficient elevation to support upper reservoirs at this ideal head height. A good symbiotic match might thus be realized by co-locating a pumped hydro plant with a reverse osmosis desalination plant, which we call an Integrated Pumped Hydro Reverse Osmosis (IPHRO) system. Combining systems reduces capital investment, such as pump costs, and solves the desalination brine disposal challenge since 10-20 times more water is required to generate one person's power needs than to generate their fresh water needs, so brine outflow can be diluted by the turbine output water reducing costs of diffusing outflow pipes. This paper describes an algorithm that weights distance from the ocean and mountain height to explore where around the world such IPHRO systems might be located. Design equations are presented to preliminarily explore the size and cost of an IPHRO system and enable first order site feasibility assessment. An example is given for providing power and water for one million people with an IPRHO system in southern California. Analysis and consideration of other sites is included in a supplementary document.