The Influence of Concentration and Temperature on the Membrane Resistance of Ion Exchange Membranes and the Levelised Cost of Hydrogen from Reverse Electrodialysis with Ammonium Bicarbonate

• Main Authors: Yash Dharmendra Raka, Robert Bock, Håvard Karoliussen, Øivind Wilhelmsen, Odne Stokke Burheim
• Format: Article
• Language: English
• Published: MDPI AG 2021-02-01
• Series: Membranes
• Subjects: reverse electrodialysis (RED); anion-exchange membrane; cation-exchange membrane; membrane resistance; membrane resistivity; ion-exchange membrane
• Online Access: https://www.mdpi.com/2077-0375/11/2/135

The ohmic resistances of the anion and cation ion-exchange membranes (IEMs) that constitute a reverse electrodialysis system (RED) are of crucial importance for its performance. In this work, we study the influence of concentration (0.1 M, 0.5 M, 1 M and 2 M) of ammonium bicarbonate solutions on the ohmic resistances of ten commercial IEMs. We also studied the ohmic resistance at elevated temperature 313 K. Measurements have been performed with a direct two-electrode electrochemical impedance spectroscopy (EIS) method. As the ohmic resistance of the IEMs depends linearly on the membrane thickness, we measured the impedance for three different layered thicknesses, and the results were normalised. To gauge the role of the membrane resistances in the use of RED for production of hydrogen by use of waste heat, we used a thermodynamic and an economic model to study the impact of the ohmic resistance of the IEMs on hydrogen production rate, waste heat required, thermochemical conversion efficiency and the levelised cost of hydrogen. The highest performance was achieved with a stack made of FAS30 and CSO Type IEMs, producing hydrogen at 8.48· 10<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msup><mrow></mrow><mrow><mo>−</mo><mn>7</mn></mrow></msup></semantics></math></inline-formula> kg m<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msubsup><mrow></mrow><mrow><mi>m</mi><mi>e</mi><mi>m</mi></mrow><mrow><mo>−</mo><mn>2</mn></mrow></msubsup></semantics></math></inline-formula>s<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msup><mrow></mrow><mrow><mo>−</mo><mn>1</mn></mrow></msup></semantics></math></inline-formula> with a waste heat requirement of 344 kWh kg<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msup><mrow></mrow><mrow><mo>−</mo><mn>1</mn></mrow></msup></semantics></math></inline-formula> hydrogen. This yielded an operating efficiency of 9.7% and a levelised cost of 7.80 € kg<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msubsup><mrow></mrow><msub><mi>H</mi><mn>2</mn></msub><mrow><mo>−</mo><mn>1</mn></mrow></msubsup></semantics></math></inline-formula>.