Heat to H2: Using Waste Heat for Hydrogen Production through Reverse Electrodialysis

This work presents an integrated hydrogen production system using reverse electrodialysis (RED) and waste heat, termed Heat to H 2 . The driving potential in RED is a concentration difference over alternating anion and cation exchange membranes, where the electrode potential can be used directly for water splitting at the RED electrodes. Low-grade waste heat is used to restore the concentration difference in RED. In this study we investigate two approaches: one water removal process by evaporation and one salt removal process. Salt is precipitated in the thermally driven salt removal, thus introducing the need for a substantial change in solubility with temperature, which KNO 3 fulfils. Experimental data of ion conductivity of K + and NO 3 − in ion-exchange membranes is obtained. The ion conductivity of KNO 3 in the membranes was compared to NaCl and found to be equal in cation exchange membranes, but significantly lower in anion exchange membranes. The membrane resistance constitutes 98% of the total ohmic resistance using concentrations relevant for the precipitation process, while for the evaporation process, the membrane resistance constitutes over 70% of the total ohmic resistance at 40 ∘ C. The modelled hydrogen production per cross-section area from RED using concentrations relevant for the precipitation process is 0.014 ± 0.009 m 3 h − 1 (1.1 ± 0.7 g h − 1 ) at 40 ∘ C, while with concentrations relevant for evaporation, the hydrogen production per cross-section area was 0.034 ± 0.016 m 3 h − 1 (2.6 ± 1.3 g h − 1 ). The modelled energy needed per cubic meter of hydrogen produced is 55 ± 22 kWh (700 ± 300 kWh kg − 1 ) for the evaporation process and 8.22 ± 0.05 kWh (104.8 ± 0.6 kWh kg − 1 ) for the precipitation process. Using RED together with the precipitation process has similar energy consumption per volume hydrogen produced compared to proton exchange membrane water electrolysis and alkaline water electrolysis, where the energy input to the Heat to H 2 -process comes from low-grade waste heat.

[1]  J. Weinstein,et al.  Electric Power from Differences in Salinity: The Dialytic Battery , 1976, Science.

[2]  Joris Proost,et al.  State-of-the art CAPEX data for water electrolysers, and their impact on renewable hydrogen price settings , 2019, International Journal of Hydrogen Energy.

[3]  Antonio Piacentino,et al.  Reverse electrodialysis heat engine for sustainable power production , 2017 .

[4]  S. Kjelstrup,et al.  The permselectivity and water transference number of ion exchange membranes in reverse electrodialysis , 2017 .

[5]  P. Liang,et al.  Optimization of membrane stack configuration for efficient hydrogen production in microbial reverse-electrodialysis electrolysis cells coupled with thermolytic solutions. , 2013, Bioresource technology.

[6]  V. Afanasiev,et al.  State of hydration shells of sodium chloride in aqueous solutions in a wide concentration range at 273.15-373.15 K. , 2009, Journal of Physical Chemistry B.

[7]  Berrin Tansel,et al.  Significance of hydrated radius and hydration shells on ionic permeability during nanofiltration in dead end and cross flow modes , 2006 .

[8]  A. A. Maryott,et al.  Dielectric constant of water from 0 to 100 C , 1956 .

[9]  R. Robinson,et al.  Ionic hydration and activity in electrolyte solutions. , 1948, Journal of the American Chemical Society.

[10]  K. Pitzer,et al.  Thermodynamics of NaCl in steam , 1986 .

[11]  Matthias Wessling,et al.  Practical potential of reverse electrodialysis as process for sustainable energy generation. , 2009, Environmental science & technology.

[12]  Dorothea C. Nijmeijer,et al.  Theoretical power density from salinity gradients using reverse electrodialysis , 2012 .

[13]  J. Post,et al.  Energy recovery from controlled mixing salt and fresh water with a reverse electrodialysis system. , 2008, Environmental science & technology.

[14]  J. Vera,et al.  Activity coefficients of sodium, potassium, and nitrate ions in aqueous solutions of NaNO3, KNO3, and NaNO3+KNO3 at 25°C , 1996 .

[15]  B. Logan,et al.  Influence of solution concentration and salt types on the performance of reverse electrodialysis cells , 2015 .

[16]  B. Logan,et al.  Hydrogen production from inexhaustible supplies of fresh and salt water using microbial reverse-electrodialysis electrolysis cells , 2011, Proceedings of the National Academy of Sciences.

[17]  Gonzalo del Alamo Serrano,et al.  Heat to H2:Using Waste Heat to Set Up Concentration Differences for Reverse Electrodialysis Hydrogen Production , 2018, ECS Transactions.

[18]  T. Isono.  Density, viscosity, and electrolytic conductivity of concentrated aqueous electrolyte solutions at several temperatures. Alkaline-earth chlorides, LaCl3, Na2SO4, NaNO3, NaBr, KNO3, KBr, and Cd(NO3)2 , 1984 .

[19]  Osamu Kobayashi,et al.  Mass production cost of PEM fuel cell by learning curve , 2004 .

[20]  G. Lu,et al.  Structure of KNO3 electrolyte solutions: a Monte Carlo study , 2004 .

[21]  G. Onori.  Ionic hydration in sodium chloride solutions , 1988 .

[22]  T. Navessin,et al.  Investigation of the through-plane impedance technique for evaluation of anisotropy of proton conducting polymer membranes , 2008 .

[23]  J. Pople,et al.  Counterion Condensation in Nafion , 2011 .

[24]  B. Freeman,et al.  Ion Diffusion Coefficients in Ion Exchange Membranes: Significance of Counterion Condensation , 2018, Macromolecules.

[25]  K. Nijmeijer,et al.  Performance-determing membrane properties in reverse electrodialysis , 2013 .

[26]  Yuan-yuan Ji,et al.  The Role of Experimental Factors in Membrane Permselectivity Measurements , 2017 .

[27]  E. Glueckauf.  The influence of ionic hydration on activity coefficients in concentrated electrolyte solutions , 1955 .

[28]  R. E. Pattle.  Production of Electric Power by mixing Fresh and Salt Water in the Hydroelectric Pile , 1954, Nature.

[29]  Kjersti Wergeland Krakhella,et al.  Energy generation and storage by salinity gradient power: A model-based assessment , 2019, Journal of Energy Storage.

[30]  D. Stolten,et al.  A comprehensive review on PEM water electrolysis , 2013 .

[31]  O. Burheim,et al.  Opportunities and challenges for thermally driven hydrogen production using reverse electrodialysis system , 2020 .

[32]  C. A. Ferreira,et al.  Measuring the proton conductivity of ion-exchange membranes using electrochemical impedance spectroscopy and through-plane cell. , 2014, The journal of physical chemistry. B.

[33]  Dongke Zhang,et al.  Recent progress in alkaline water electrolysis for hydrogen production and applications , 2010 .

[34]  F. Barbir.  PEM electrolysis for production of hydrogen from renewable energy sources , 2005 .

[35]  R. Lacey.  Energy by reverse electrodialysis , 1980 .

[36]  U. K. Mudali,et al.  New Data on Activity Coefficients of Potassium, Nitrate, and Chloride Ions in Aqueous Solutions of KNO3 and KCl by Ion Selective Electrodes , 2012 .

[37]  B. Logan,et al.  Comparison of hydrogen production and electrical power generation for energy capture in closed-loop ammonium bicarbonate reverse electrodialysis systems. , 2014, Physical chemistry chemical physics : PCCP.

[38]  A. J. Sobral,et al.  Mean distance of closest approach of potassium, cesium and rubidium ions in aqueous solutions: Experimental and theoretical calculations , 2009 .

[39]  J. Sangster,et al.  A General Method of Calculating the Water Activity of Supersaturated Aqueous Solutions from Ternary Data , 1973 .

[40]  H. Hamelers,et al.  Energy efficiency of a concentration gradient flow battery at elevated temperatures , 2017 .

[41]  Wei Liu,et al.  Hybrid membrane distillation-reverse electrodialysis electricity generation system to harvest low-grade thermal energy , 2017 .

[42]  Gerald L. Wick,et al.  Power from salinity gradients , 1978 .

[43]  Joo-Youn Nam,et al.  Hydrogen generation in microbial reverse-electrodialysis electrolysis cells using a heat-regenerated salt solution. , 2012, Environmental science & technology.

[44]  E. Drioli,et al.  Salinity gradient power-reverse electrodialysis and alkaline polymer electrolyte water electrolysis for hydrogen production , 2016 .

[45]  Luisa F. Cabeza,et al.  Methods to estimate the industrial waste heat potential of regions – A categorization and literature review , 2014 .

[46]  K. Xiao,et al.  Power generation by coupling reverse electrodialysis and ammonium bicarbonate: Implication for recovery of waste heat , 2012 .

[47]  B. Freeman,et al.  Effect of fixed charge group concentration on salt permeability and diffusion coefficients in ion exchange membranes , 2018, Journal of Membrane Science.