scholarly journals Energy Harvesting from Brines by Reverse Electrodialysis Using Nafion Membranes

Membranes ◽  
2020 ◽  
Vol 10 (8) ◽  
pp. 168 ◽  
Author(s):  
Ahmet H. Avci ◽  
Diego A. Messana ◽  
Sergio Santoro ◽  
Ramato Ashu Tufa ◽  
Efrem Curcio ◽  
...  
Keyword(s):  
Energy Conversion ◽  
Electrochemical Properties ◽  
Cation Exchange ◽  
Power Density ◽  
Electrochemical Impedance ◽  
Salinity Gradient ◽  
Superior Performance ◽  
Reverse Electrodialysis ◽  
Nafion Membranes ◽  
The Impact

Ion exchange membranes (IEMs) have consolidated applications in energy conversion and storage systems, like fuel cells and battery separators. Moreover, in the perspective to address the global need for non-carbon-based and renewable energies, salinity-gradient power (SGP) harvesting by reverse electrodialysis (RED) is attracting significant interest in recent years. In particular, brine solutions produced in desalination plants can be used as concentrated streams in a SGP-RED stack, providing a smart solution to the problem of brine disposal. Although Nafion is probably the most prominent commercial cation exchange membrane for electrochemical applications, no study has investigated yet its potential in RED. In this work, Nafion 117 and Nafion 115 membranes were tested for NaCl and NaCl + MgCl2 solutions, in order to measure the gross power density extracted under high salinity gradient and to evaluate the effect of Mg2+ (the most abundant divalent cation in natural feeds) on the efficiency in energy conversion. Moreover, performance of commercial CMX (Neosepta) and Fuji-CEM 80050 (Fujifilm) cation exchange membranes, already widely applied for RED applications, were used as a benchmark for Nafion membranes. In addition, complementary characterization (i.e., electrochemical impedance and membrane potential test) was carried out on the membranes with the aim to evaluate the predominance of electrochemical properties in different aqueous solutions. In all tests, Nafion 117 exhibited superior performance when 0.5/4.0 M NaCl fed through 500 µm-thick compartments at a linear velocity 1.5 cm·s−1. However, the gross power density of 1.38 W·m−2 detected in the case of pure NaCl solutions decreased to 1.08 W·m−2 in the presence of magnesium chloride. In particular, the presence of magnesium resulted in a drastic effect on the electrochemical properties of Fuji-CEM-80050, while the impact on other membranes investigated was less severe.

Harvesting Natural Salinity Gradient Energy for Hydrogen Production Through Reverse Electrodialysis Power Generation

2017 ◽  
Vol 14 (2) ◽  
Author(s):  
Mohammadreza Nazemi ◽  
Jiankai Zhang ◽  
Marta C. Hatzell
Keyword(s):  
Energy Efficiency ◽  
Power Density ◽  
External Load ◽  
Salinity Gradient ◽  
Electrical Power ◽  
Ionic Current ◽  
Electrical Energy ◽  
Hydrogen Energy ◽  
Mixing Processes ◽  
Reverse Electrodialysis

There is an enormous potential for energy generation from the mixing of sea and river water at global estuaries. Here, we model a novel approach to convert this source of energy directly into hydrogen and electricity using reverse electrodialysis (RED). RED relies on converting ionic current to electric current using multiple membranes and redox-based electrodes. A thermodynamic model for RED is created to evaluate the electricity and hydrogen which can be extracted from natural mixing processes. With equal volume of high and low concentration solutions (1 L), the maximum energy extracted per volume of solution mixed occurred when the number of membranes is reduced, with the lowest number tested here being five membrane pairs. At this operating point, 0.32 kWh/m3 is extracted as electrical energy and 0.95 kWh/m3 as hydrogen energy. This corresponded to an electrical energy conversion efficiency of 15%, a hydrogen energy efficiency of 35%, and therefore, a total mixing energy efficiency of nearly 50%. As the number of membrane pairs increases from 5 to 20, the hydrogen power density decreases from 13.6 W/m2 to 2.4 W/m2 at optimum external load. In contrast, the electrical power density increases from 0.84 W/m2 to 2.2 W/m2. Optimum operation of RED depends significantly on the external load (external device). A small load will increase hydrogen energy while decreasing electrical energy. This trade-off is critical in order to optimally operate an RED cell for both hydrogen and electricity generation.

scholarly journals Design of Monovalent Ion Selective Membranes for Reducing the Impacts of Multivalent Ions in Reverse Electrodialysis

Membranes ◽  
2019 ◽  
Vol 10 (1) ◽  
pp. 7 ◽  
Author(s):  
Abreham Tesfaye Besha ◽  
Misgina Tilahun Tsehaye ◽  
David Aili ◽  
Wenjuan Zhang ◽  
Ramato Ashu Tufa
Keyword(s):  
Negative Impact ◽  
Salinity Gradient ◽  
Open Circuit ◽  
Anion Exchange Membranes ◽  
Promising Alternative ◽  
Reverse Electrodialysis ◽  
Multivalent Ions ◽  
Monovalent Ion ◽  
The Impact ◽  
Selective Membranes

Reverse electrodialysis (RED) represents one of the most promising membrane-based technologies for clean and renewable energy production from mixing water solutions. However, the presence of multivalent ions in natural water drastically reduces system performance, in particular, the open-circuit voltage (OCV) and the output power. This effect is largely described by the “uphill transport” phenomenon, in which multivalent ions are transported against the concentration gradient. In this work, recent advances in the investigation of the impact of multivalent ions on power generation by RED are systematically reviewed along with possible strategies to overcome this challenge. In particular, the use of monovalent ion-selective membranes represents a promising alternative to reduce the negative impact of multivalent ions given the availability of low-cost materials and an easy route of membrane synthesis. A thorough assessment of the materials and methodologies used to prepare monovalent selective ion exchange membranes (both cation and anion exchange membranes) for applications in (reverse) electrodialysis is performed. Moreover, transport mechanisms under conditions of extreme salinity gradient are analyzed and compared for a better understanding of the design criteria. The ultimate goal of the present work is to propose a prospective research direction on the development of new membrane materials for effective implementation of RED under natural feed conditions.

scholarly journals Potential of brackish water and brine for energy generation by salinity gradient power-reverse electrodialysis (SGP-RE)

RSC Advances ◽  
2014 ◽  
Vol 4 (80) ◽  
pp. 42617-42623 ◽  
Author(s):  
Ramato Ashu Tufa ◽  
Efrem Curcio ◽  
Willem van Baak ◽  
Joost Veerman ◽  
Simon Grasman ◽  
...  
Keyword(s):  
Power Density ◽  
Brackish Water ◽  
Salinity Gradient ◽  
Energy Generation ◽  
Maximum Power ◽  
Maximum Power Density ◽  
Cell Pair ◽  
Reverse Electrodialysis ◽  
Solar Pond ◽  
Salinity Gradient Power

Salinity Gradient Power-Reverse Electrodialysis (SGP-RE), tested on brackish water/solar pond brine, resulted in maximum power density of 1.13 W m−2 cell pair, 63% less than that of pure NaCl solutions with comparable salinity.

scholarly journals MODERN RESEARCH METHODS OF PHYSICOCHEMICAL AND ELECTROCHEMICAL PROPERTIES OF ELECTROLYTES IN FOR Li-ION BATTERIES AND HYBRID SUPERCAPACITIES

2021 ◽  
Vol 87 (6) ◽  
pp. 82-96
Author(s):  
Viktor Diamant
Keyword(s):  
Thermal Stability ◽  
Electrochemical Impedance Spectroscopy ◽  
Impedance Spectroscopy ◽  
Electrochemical Properties ◽  
Power Density ◽  
Electrochemical Impedance ◽  
Aqueous Electrolytes ◽  
Li Ion Batteries ◽  
Power Sources ◽  
Li Ion

In review examineі base properties of modern non-aqueous electrolytes for li-ion batteries and hybrid supercapacities taking part in the formation of power density, electrochemical and thermal stability. Discussed such aspects as the electrolytes functions in electrochemical power sources, physicochemical and electrochemical properties of electrolytes for supercapacitors, the physicochemical and electrochemical properties of electrolytes for primary and secondary batteries, and methods of electrolytes research. As the base methodі for electrolytes studies considered: electrochemical impedance spectroscopy, voltammetry, amperometry, viscosimetry, and combined Ramman spectroscopy.  

scholarly journals Large-scale, robust mushroom-shaped nanochannel array membrane for ultrahigh osmotic energy conversion

2021 ◽  
Vol 7 (21) ◽  
pp. eabg2183
Author(s):  
Chao Li ◽  
Liping Wen ◽  
Xin Sui ◽  
Yiren Cheng ◽  
Longcheng Gao ◽  
...  
Keyword(s):  
Energy Conversion ◽  
Power Density ◽  
Single Molecule ◽  
Self Assembly ◽  
Large Scale ◽  
Mechanical Stability ◽  
Salinity Gradient ◽  
Clean Energy ◽  
Selective Layer ◽  
Nanochannel Array

The osmotic energy, a large-scale clean energy source, can be converted to electricity directly by ion-selective membranes. None of the previously reported membranes meets all the crucial demands of ultrahigh power density, excellent mechanical stability, and upscaled fabrication. Here, we demonstrate a large-scale, robust mushroom-shaped (with stem and cap) nanochannel array membrane with an ultrathin selective layer and ultrahigh pore density, generating the power density up to 22.4 W·m−2 at a 500-fold salinity gradient, which is the highest value among those of upscaled membranes. The stem parts are a negative-charged one-dimensional (1D) nanochannel array with a density of ~1011 cm−2, deriving from a block copolymer self-assembly; while the cap parts, as the selective layer, are formed by chemically grafted single-molecule–layer hyperbranched polyethyleneimine equivalent to tens of 1D nanochannels per stem. The membrane design strategy provides a promising approach for large-scale osmotic energy conversion.

ENERGY CONVERSION FROM SALINITY GRADIENT USING MICROCHIP WITH NAFION MEMBRANE

2016 ◽  
Vol 42 ◽  
pp. 1660183 ◽  
Author(s):  
CHE-RONG CHANG ◽  
CHING-HUA YEH ◽  
HUNG-CHUN YEH ◽  
RUEY-JEN YANG
Keyword(s):  
Energy Conversion ◽  
Salt Solution ◽  
Ph Value ◽  
Salinity Gradient ◽  
Ion Selectivity ◽  
Electrical Energy ◽  
Diffusion Potential ◽  
Reverse Electrodialysis ◽  
Selective Membrane ◽  
The Difference

When a concentrated salt solution and a diluted salt solution are separated by an ion-selective membrane, cations and anions would diffuse at different rates depending on the ion selectivity of the membrane. The difference of positive and negative charges at both ends of the membrane would produce a potential, called the diffusion potential. Thus, electrical energy can be converted from the diffusion potential through reverse electrodialysis. This study demonstrated the fabrication of an energy conversion microchip using the standard micro-electromechanical technique, and utilizing Nafion junction as connecting membrane, which was fabricated by a surface patterned process. Through different salinity gradient of potassium chloride solutions, we experimentally investigated the diffusion potential and power generation from the microchip, and the highest value measured was 135 mV and 339 pW, respectively. Furthermore, when the electrolyte was in pH value of 3.8, 5.6, 10.3, the system exhibited best performance at pH value of 10.3; whereas, pH value of 3.8 yielded the worst.

Effect of Pore Morphology on the Electrochemical Properties of Electric Double Layer Carbon Cryogel Supercapacitors

2007 ◽  
Vol 1056 ◽  
Author(s):  
Betzaida Batalla Garcia ◽  
Aaron M. Feaver ◽  
Richard Champion ◽  
Qifeng Zhang ◽  
Tim T. Fister ◽  
...  
Keyword(s):  
Electrochemical Properties ◽  
Electrochemical Impedance ◽  
Porous Electrode ◽  
Low Frequency ◽  
Frequency Range ◽  
Low Frequencies ◽  
Diffusion Dynamics ◽  
Pore Size Distributions ◽  
Complex Capacitance ◽  
The Impact

ABSTRACTIn this study a group of resorcinol-formaldehyde carbon cryogels (CC) have been processed chemically, via catalysis and activation, to obtain varied nanostructures and pore size distributions. To understand the relation between structure and electrochemical properties the capacitor can be studied as a dielectric system composed of a porous electrode and the electrolyte (Tetraethylammonium tetrafluoroborate in propylene carbonate). Using Electrochemical impedance spectroscopy (EIS) the complex capacitance and power are used to study the behavior of the system below the relaxation frequency fo (φ = −45°). Therefore, the relaxation of the capacitor system at the low frequency range, f < fo, may be used as a measure of pore/electrolyte interaction. The approach here proposed also allows for a direct experimental characterization of the capacitance and power at low frequencies where small pores are likely to affect the diffusion dynamics of the electrolyte molecules. The results suggest a correlation between the occurrence of small micropores and that of high power losses that are related to the resistive element produced at the low frequency range. Moreover, the impact of the micropore structure upon the supercapacitor's performance is apparent in its capacitance and energy as well. In addition to the complex power and capacitance other measurements including BET Nitrogen sorption, cyclic voltammetry, galvanic cycling and X-Ray Raman Scattering were used to characterize the samples and support these results.

Harvesting Natural Salinity Gradient Energy for Hydrogen Production Through Reverse Electrodialysis (RED) Power Generation

2016 ◽  
Author(s):  
Mohammadreza Nazemi ◽  
Jiankai Zhang ◽  
Marta Hatzell
Keyword(s):  
Power Density ◽  
Current Density ◽  
Salinity Gradient ◽  
Electrical Energy ◽  
Hydrogen Energy ◽  
External Resistance ◽  
Membrane Area ◽  
Reverse Electrodialysis ◽  
Gradient Energy

There is an enormous potential for energy generation from the mixing of sea and river water at global estuaries. If technologies are developed which are capable of converting this energy into a usable form (electricity or fuels), salinity gradient energy may be able to dramatically increase the worlds supply of renewable energy. Here we present a novel approach to convert this source of energy directly into hydrogen and electricity using Reverse Electrodialysis (RED). RED relies on converting ionic current to electric current using multiple membranes and redox based electrodes. A thermodynamic model for RED is created to evaluate the electricity and hydrogen which can be extracted from natural mixing processes. With equal volumes of HC and LC solutions (0.001m3), the maximum energy extracted is found to occur with 5 number of membrane pairs. At this operating point, 0.4 kWh/m3 can be extracted as electrical energy and 0.95 kWh/m3 of energy is extracted as hydrogen energy. The electrical energy conversion efficiency approaches 15%, whereas the hydrogen energy efficiency is 35%. Overall, the maximum system conversion of Gibbs free energy to electrical and hydrogen energy approaches 50%. The results show that as the number of membrane pairs increases from 5 to 20, the hydrogen power density decreases from 13.2 W/m2 to 3.7 W/m2. Likewise, the power density from electrical energy decreases from 1 W/m2 to 0.3 W/m2. This is because of increase in the total membrane area as increasing the number of membrane pairs. The stack voltage increased from 1.5V to 6V as the number of membrane pairs is increased from 5 to 20. This corresponds to an increase in internal resistance from 600 Ω.cm2 to 2400 Ω.cm2. Long term trade-off between improving the system voltage, while decreasing the system resistance will be crucial for improved long term RED performance. Furthermore, optimum operation of RED, depends on proper selection of external resistance. A small external resistance will increase hydrogen energy and decrease electrical energy, particularly using a small number of membrane pairs. With the fixed small external resistance, as increasing the number of membrane pairs, the difference between internal and external resistance increases. Therefore, the load potential and current density do not increase considerably. For the cases analyzed with 8.29 Ω.cm2 external resistance, the maximum current density increases from 11.1 mA/cm2 to 12.4 mA/cm2 as the number of membrane pairs increases from 5 to 20. Likewise, the load potential rises from 92 mV to 102 mV.

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