Hydrogen-Electrodialysis with Bipolar Membrane (H-EDBM): First experiments and preliminary economic evaluation

Abstract

In the present work Electrodialysis with Bipolar Membranes (EDBM) for brine valorisation is for the first time investigated for the simultaneous production of hydrogen and chemicals. EDBM allows current densities one order of magnitude higher than ED and RED electro-membrane processes, making the technology more attractive to the hydrogen market. In this work, an experimental campaign with the Hydrogen-EDBM (H-EDBM) was conducted for the first time, investigating different configurations consisting of different end-membranes for the electrode compartments. The results showed 98 % ±2 % faradic efficiency for hydrogen production, with a productivity of up to 18.4 mol h-1 m- 2 at the current density of 1000 A m- 2. In addition, the Bipolar Membranes allow the simultaneous production of chemicals such as NaOH, for which a Current Efficiency of 96 % and a Specific Energy Consumptions (SECs) of 1.78 kWh kgNaOH - 1 were obtained. Eventually, the research was completed with a preliminary economic analysis combining the different operations and costs of the tested configurations in order to identify the optimum of the process. The Levelized Costs Of Hydrogen (LCOH) and of NaOH (LCONaOH) were used as performance parameters. The minimum LCONaOH of 0.13 € kgNaOH - 1 and LCOH of 2.4 € kgH2 - 1 were found when bipolar membranes are used as end-membranes and the unit is coupled with onshore wind plant, identifying this configuration as the most promising. Collected results show a great potential for the H-EDBM, thus fully justifying future more in-depth analyses.