Harnessing Energy from Osmotic Gradients of RO Brine

This chapter explores the potential and challenges of extracting salinity gradient energy (SGE) using pressure-retarded osmosis (PRO) and reverse electrodialysis (RED) processes. It covers the principles of SGE and the power generation theories behind both processes. Despite extensive research on PRO, its commercial viability faces challenges due to energetic inputs and losses, with a need for innovative technological improvements and integration with reverse osmosis (RO) desalination to enhance sustainability. Furthermore, economic assessments are crucial to determine the cost-effectiveness of the PRO process when utilizing high-salinity solutions such as RO brine. The RED has similar challenges mainly related to low power densities and fouling of ion exchange membranes (IEMs) which can hinder commercialization. Future research should focus on developing energy-efficient pretreatment technologies, antifouling membranes, and low-cost IEMs to improve performance and reduce costs. Establishing standardized operational guidelines is also necessary to ensure the durability and reliability of RED systems. Overall, advancements in both processes hold promise for more efficient and sustainable energy generation from salinity gradients using RO brine.