Conductive Reverse Electrodialysis for Salinity Gradient Energy
Avci, Ahmet Halil LU and Lipnizki, Frank LU
(2023)
M3-S "Applied polymers, nanomaterials, membranes, and composites"
- Abstract
Salinity gradient energy (SGE) can play an important role in the energy transition from fossil-based sources to renewable sources. Its potential is estimated to be around 625 TWh·a-1 corresponding to 3% of global electricity consumption [1]. SGE sources are most abundant in the estuaries where rivers meet seawater. However, it is also available in different forms such as brackish water, brine etc [2].
Reverse electrodialysis (RED) has been subject to several research studies that investigate the potential of salinity gradient energy. It is a membrane-based technology that allows a controlled and preferential ion transfer environment. The simplest unit of RED is called a cell and consists of 4 key elements: a low concentration... (More)
Salinity gradient energy (SGE) can play an important role in the energy transition from fossil-based sources to renewable sources. Its potential is estimated to be around 625 TWh·a-1 corresponding to 3% of global electricity consumption [1]. SGE sources are most abundant in the estuaries where rivers meet seawater. However, it is also available in different forms such as brackish water, brine etc [2].
Reverse electrodialysis (RED) has been subject to several research studies that investigate the potential of salinity gradient energy. It is a membrane-based technology that allows a controlled and preferential ion transfer environment. The simplest unit of RED is called a cell and consists of 4 key elements: a low concentration compartment, a cation exchange membrane, a high concentration compartment and an anion exchange membrane. The compartments are defined by replacing spacers which defines the intermembrane distance and acts as a turbulence promoter. Hundreds of cells can be piled up between electrode compartments that convert chemical energy to electrical energy by red-ox reactions.
The extracted power in RED is limited by the high resistance of low concentration compartment, especially when a solution having equivalent concentration to river water or less is used as feed. In this work, , we aimed to demonstrate a conductive RED (cRED) design that can facilitate the ion transport while, in addition, alleviating so called spacer shadow effect. In total, four different stack designs were assembled by substituting the conventional spacers with cation exchange resins. The results were evaluated by comparing the electrochemical properties of the four stack designs by mixing different solutions representing possible natural sources. River water, wastewater treatment plant effluents (0.017 M NaCl), brackish water (0.1 M NaCl) and seawater (0.51 M NaCl) were fed as dilute solution while seawater, seawater reverse osmosis brine (1.0 M NaCl) and hypersaline brine (4.0 M NaCl) were used as concentrate.
Substantial improvement in generated power density was achieved when comparing cRED designs to the conventional RED design. In particular, 2.6 to 5.4 times higher power densities were achieved in the cRED design with both compartments loaded with cation exchange resins. Electrochemical characterization indicated that the main reason for this enhancement was due to the decrease in stack resistance while increase in open circuit voltage was limited to 1.1 – in the best scenario. Comprehensive analysis of the data suggests that the decrease in resistance was due to two reasons: elimination of spacer shadow effects and facilitated ion transport. The impact of former was dominant in case of using solutions having concentration brackish water equivalent or higher while using low concentration feed, such as river water, was beneficial promoting also latter effect.
Anticipated outcomes of employing cRED design to address limitations in low concentration compartment resistance include expediting the preparation of ion exchange membranes with reduced resistance. This advancement could significantly enhance the effectiveness of such a design.
Acknowledgements
The authors would like to express their appreciation for the financial support of Swedish Energy Agency, Sweden (ref. 51675-1).
References
[1] Alvarez-Silva et al., Renew. Sustain. Energy Rev, 60 (2016) 1387–1395.
[2] Tedesco et al., J. Memb. Sci, 500 (2016) 33–45
(Less)
Please use this url to cite or link to this publication:
https://lup.lub.lu.se/record/8899c0f2-be13-484b-ba0d-537e673df168
- author
- Avci, Ahmet Halil
LU
and Lipnizki, Frank
LU
- organization
- publishing date
- 2023-09-26
- type
- Contribution to conference
- publication status
- unpublished
- subject
- keywords
- Membrane processes, Reverse electrodialysis
- pages
- 1 pages
- conference name
- M3-S "Applied polymers, nanomaterials, membranes, and composites"
- conference location
- Torun, Poland
- conference dates
- 2023-09-26 - 2023-09-28
- project
- Harvesting of Blue energy using Swedish natural and artificial resources
- language
- English
- LU publication?
- yes
- id
- 8899c0f2-be13-484b-ba0d-537e673df168
- date added to LUP
- 2026-01-02 13:10:21
- date last changed
- 2026-01-19 13:57:57
@misc{8899c0f2-be13-484b-ba0d-537e673df168,
abstract = {{<br/>Salinity gradient energy (SGE) can play an important role in the energy transition from fossil-based sources to renewable sources. Its potential is estimated to be around 625 TWh·a-1 corresponding to 3% of global electricity consumption [1]. SGE sources are most abundant in the estuaries where rivers meet seawater. However, it is also available in different forms such as brackish water, brine etc [2]. <br/>Reverse electrodialysis (RED) has been subject to several research studies that investigate the potential of salinity gradient energy. It is a membrane-based technology that allows a controlled and preferential ion transfer environment. The simplest unit of RED is called a cell and consists of 4 key elements: a low concentration compartment, a cation exchange membrane, a high concentration compartment and an anion exchange membrane. The compartments are defined by replacing spacers which defines the intermembrane distance and acts as a turbulence promoter. Hundreds of cells can be piled up between electrode compartments that convert chemical energy to electrical energy by red-ox reactions.<br/>The extracted power in RED is limited by the high resistance of low concentration compartment, especially when a solution having equivalent concentration to river water or less is used as feed. In this work, , we aimed to demonstrate a conductive RED (cRED) design that can facilitate the ion transport while, in addition, alleviating so called spacer shadow effect. In total, four different stack designs were assembled by substituting the conventional spacers with cation exchange resins. The results were evaluated by comparing the electrochemical properties of the four stack designs by mixing different solutions representing possible natural sources. River water, wastewater treatment plant effluents (0.017 M NaCl), brackish water (0.1 M NaCl) and seawater (0.51 M NaCl) were fed as dilute solution while seawater, seawater reverse osmosis brine (1.0 M NaCl) and hypersaline brine (4.0 M NaCl) were used as concentrate. <br/>Substantial improvement in generated power density was achieved when comparing cRED designs to the conventional RED design. In particular, 2.6 to 5.4 times higher power densities were achieved in the cRED design with both compartments loaded with cation exchange resins. Electrochemical characterization indicated that the main reason for this enhancement was due to the decrease in stack resistance while increase in open circuit voltage was limited to 1.1 – in the best scenario. Comprehensive analysis of the data suggests that the decrease in resistance was due to two reasons: elimination of spacer shadow effects and facilitated ion transport. The impact of former was dominant in case of using solutions having concentration brackish water equivalent or higher while using low concentration feed, such as river water, was beneficial promoting also latter effect.<br/>Anticipated outcomes of employing cRED design to address limitations in low concentration compartment resistance include expediting the preparation of ion exchange membranes with reduced resistance. This advancement could significantly enhance the effectiveness of such a design.<br/>Acknowledgements<br/>The authors would like to express their appreciation for the financial support of Swedish Energy Agency, Sweden (ref. 51675-1).<br/>References<br/>[1] Alvarez-Silva et al., Renew. Sustain. Energy Rev, 60 (2016) 1387–1395.<br/>[2] Tedesco et al., J. Memb. Sci, 500 (2016) 33–45<br/>}},
author = {{Avci, Ahmet Halil and Lipnizki, Frank}},
keywords = {{Membrane processes; Reverse electrodialysis}},
language = {{eng}},
month = {{09}},
title = {{Conductive Reverse Electrodialysis for Salinity Gradient Energy}},
year = {{2023}},
}