Coupling Hydrodynamic and Energy Production Models for Salinity Gradient Energy Assessment in a Salt-Wedge Estuary (Strymon River, Northern Greece)

Abstract

Salinity gradient energy (SGE) plants generate power from the mixing of salt water and fresh water using advanced membrane systems. In the Strymon River, under low-flow conditions, a salt wedge is formed, developing a two-layer stratified system, which could be used to extract SGE. In this paper, a novel study was implemented by coupling a 3D hydrodynamic model simulating the salt wedge flow, with the SGE model which assesses the net energy produced by a 1 MW SGE plant. Two scenarios were followed: (a) the optimal scenario, operating throughout the year by mixing salt water from the sea (38.1 g/L) and fresh water (0.1 g/L) from the river to produce 4.15 GWh/yr, and (b) the seasonal scenario, utilizing the salinity difference of the salt wedge. Results show that the daily net SGE production varies between 0.30 and 10.90 MWh/day, in accordance with the salinity difference (ΔSsw ~15–30 g/L). Additionally, a retrospective assessment (from 1981 to 2010) of the annual and seasonal net energy production was conducted. This analysis illustrates that the salt-wedge formation (spring to late summer) coincides with the period of increased regional electricity demand. In the future, the emerging SGE could serve as a decentralized renewable energy source, enhancing energy security in the region.

Examining the Potential of Marine Renewable Energy: A Net Energy Perspective

“…In a modeling exercise (not an LCA), ref. [158] estimated the net energy produced during the operation phase of a 1 MW SGE plant in the Strymon River (Greece). However, neither [155,157] reported the CED or energy intensity of the studied systems, hence their EROI cannot be estimated.…”

“…However, neither [155,157] reported the CED or energy intensity of the studied systems, hence their EROI cannot be estimated. Similarly, in [158], only the energy required during operation is reported, while the energy embedded in the construction and decommissioning phases are not taken into account. According to this, the EROI cannot be reliably estimated.…”