Life cycle assessment of salinity gradient energy recovery by reverse electrodialysis in a seawater reverse osmosis desalination plant

Carolina Tristán,Antonio Dominguez-Ramos,Marta Rumayor,Inmaculada Ortiz,Raquel Ibáñez,Marcos Fallanza

doi:10.1039/d0se00372g

Carolina Tristán, Antonio Dominguez-Ramos + Show 4 more

Open Access

https://doi.org/10.1039/d0se00372g

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Abstract

LCA of lab-scale and large-scale stand-alone RED stacks and an up-scaled RED system co-located with a SWRO desalination plant.

Highlights

Salinity gradient is an untapped renewable energy source envisaged as a candidate to advance the progressive decarbonisation of the current electric energy portfolio under particular technical conditions.[1,2]
Reverse electrodialysis (RED), the reverse of the conventional desalination process i.e. electrodialysis, is an electrochemical membrane process that makes use of ion-exchange membranes (IEM) to recover the energy released in the reversible mixing of two solutions with different salinities.[2]
To quantify the potential environmental benefits of Salinity gradient energy capture by reverse electrodialysis (SGE-RED) in such processes, this study addresses the environmental loads avoided in a hybrid seawater reverse osmosis (SWRO)-RED configuration

Summary

Introduction

Salinity gradient is an untapped renewable energy source envisaged as a candidate to advance the progressive decarbonisation of the current electric energy portfolio under particular technical conditions.[1,2] Reverse electrodialysis (RED) stands out among membrane-based technologies to harvest salinity gradient energy (SGE).[1]. Each cell pair is comprised of an anion- and a cation-exchange membrane, with net polymer spacers placed in between to form the channels within the dilute and concentrate salt feed solutions flow. The chemical potential difference between the concentrate and diluate salt solutions gives rise to an electric potential difference over each membrane and drives the migration and diffusion of ions across membranes with opposing-charge functional groups, resulting in an ionic flux that is converted into an electron flux through redox reactions at the electrodes. The DC electric current and voltage yielded by the RED pile are readily accessible to power an external electric load connected to the RED electrodes

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