Design of housing and mesh spacer supports for salinity gradient hydroelectric power generation using pressure retarded osmosis

Pressure retarded osmosis is a technique for recovering salinity gradient energy, and new technology proposed as a renewable energy resource. Two water bodies with differing salt concentrations are separated by a membrane which is permeable to water but not to salt, and water is driven toward the section of high salinity, where its hydraulic pressure can be recovered as hydroelectric power. This paper briefly describes PRO development, and describes the design of a simple custom-built bench-scale PRO demonstration module. The feasibility of the process is confirmed and experimental results are compared with those of other researchers and with theoretical predictions. A cellulose membrane is used to separate the feed (fresh water) and draw (saline water) solutions, supported by a steel mesh. The geometry and relative opening area of this mesh spacer is investigated for its effect on water transport and calculated power density. This work lays a foundation for optimization of the mesh spacer for desired membrane performance, and for improved understanding of the fluid and molecular dynamics at the membrane interface.