A techno-economic process model for pressure retarded osmosis based energy recovery in desalination plants

Existing desalination plants face the challenges of high energy costs and environmental impacts from brine disposal. Pressure retarded osmosis (PRO) is a technology that could mitigate these issues. PRO works by capturing the potential energy in the salinity gradient between brine and dilute (e.g. freshwater/wastewater) solutions. In this study, we developed a Python-based model called Propmod that uses both internal and userdefined inputs to simulate how a full-scale PRO system performs energetically and economically. The Tampa Bay Seawater Desalination Plant was used as a case study, and if a PRO system was installed in this plant, it could potentially save 9% of the energy consumed per m(3) of permeate, while also diluting the brine from 66 to 41 ppt. Sensitivity and uncertainty analysis on the net present value of potential full-scale PRO systems indicated that the most influential parameters on PRO system performance are membrane characteristics (salt permeability, water permeability, and structural parameter), as well as energy price and feed water transmission pipe size and length. Overall, PRO systems were found to be competitive with other forms of renewable energy in areas that allow systems to be designed with higher rates of energy generation and minimal capital and operational costs.