Chapter 2 - Water Flux and Reverse Salt Flux

Abstract

Following the increase in the world population and the demand for economic development, the need for energy has increased day by day. Rapidly increasing global energy consumption is supplied mainly by fossil fuels bearing the risk of exhaustion with decreasing reserves, which now have the effect of carbon emissions and greenhouse gases. These concerns lead humanity to significantly reduce the use of fossil fuels. Salinity gradient energy (SGP), a type of hydroelectric energy, also has a high potential to displace fossil fuels. SGP is less periodic than sources like wind and solar energy. The osmotic pressure gradient energy uses the released energy during mixing of the water currents with different salinity The Gibbs free energy from mixing two solutions of different concentrations is an unnoticed source of energy. Salinity gradient energy, also referred to as osmotic energy or blue energy, can be derived from natural sources such as clean river water, salt water, and desalination of seawater. Various approaches have been developed to capture salinity gradient energy, but the most promising are pressure-retarded osmosis (PRO), reverse electrodialysis (RED) and forward osmosis (FO) processes. In this chapter theoretical approaches derived from the current literature is presented for the deep conceptual understanding of the water flux and reverse salt flux issues.