Power generation system based on pressure retarded osmosis with a commercially-available hollow fiber PRO membrane module using seawater and freshwater

Abstract

Abstract This study evaluates the feasibility of a power generation system adopting pressure retarded osmosis (PRO) using seawater and fresh water. The authors measured the membrane power density of a commercially available hollow fiber membrane module. The power density of the current membrane module is 3.1\xa0W/m2, but 6.5\xa0W/m2 is required to realize a commercially feasible power plant adopting PRO. In this case of the net output power is 2.8\xa0W/m2 when the DS pressure was 1.5\xa0MPa and the FS pressure was 0.1\xa0MPa, respectively. The cost of power generation is 0.20 $/kWh assuming a commercial plant that uses 1 million m3 of seawater per day and has the calculated membrane power density. It is necessary to improve the A and B values per membrane module to realize this system. Here, the A and B values are coefficients representing water permeability and salt permeability, respectively. The target membrane power density can be achieved using A and B values per membrane module of 2.05\xa0×\xa010−6\xa0m/s/MPa and 5.5\xa0×\xa010−9\xa0m/s, respectively. This evaluation is based on theoretical calculations using the solution-diffusion model of membrane permeation in PRO.