Pressure retarded osmosis in the renewable energy transition: Opportunities, challenges, and cost analysis for coastal river systems in Türkiye

Pressure Retarded Osmosis (PRO) has emerged as a promising renewable energy technology due to its sustainability, continuous operation capability, and potential to provide baseload power. Unlike intermittent renewable energy sources such as wind and solar, PRO utilizes the salinity gradient between freshwater and seawater to generate electricity without fuel consumption or direct greenhouse gas emissions, making it an environmentally friendly energy option. In recent years, PRO technology has advanced from laborator scale studies to pilot scale projects, with several initiatives worldwide moving toward commercial scale deployment. This progress highlights the growing interest in PRO as a complementary component of future low carbon energy systems. Although no PRO facilities are currently in operation in Türkiye, the country has significant potential for PRO development, particularly along rivers discharging into the Aegean and Mediterranean Seas, where strong salinity gradients exist. In this study, the Ceyhan River was identified as one of the most suitable locations for a PRO power plant. The Levelized Cost of Energy (LCOE) of the proposed facility was estimated at 0.238 USD/kWh. While this value is consistent with existing literature, it remains considerably higher than that of established renewable energy technologies such as hydropower, wind, and solar energy. The main challenges hindering the widespread adoption of PRO include high capital costs, limited membrane lifespan, low membrane permeability, and significant internal energy consumption. Nevertheless, ongoing advancements in membrane technology and system optimization indicate that PRO could become a viable and competitive renewable energy option in the near future, both in Türkiye and globally.