Techno-Economic Assessment of Electrodialysis with Bipolar Membranes for Hydrogen Production

The research for low-pollution fuels has shown that hydrogen can replace fossil fuels in different sectors such as transport, industry and energy production. As an alternative to water electrolysers, hydrogen can be produced from electro-membrane processes, which are generally used for desalination, energy recovery as well as for chemicals production. The technical feasibility of using such processes for the production of green hydrogen has already been demonstrated. Hydrogen-ElectroDialysis with Bipolar Membrane (H-EDBM), which couples hydrogen production with acid and base solutions generation, resulted particularly advantageous thanks to the higher current densities involved. The present work aims to conduct a thorough investigation of the H-EDBM process. A multi-scale model was modified to account for the electrode behaviour and used to simulate an industrial-scale H-EDBM unit working at 1000 A m-2 , for which the NaOH stream target was 1 M concentrated. To increase the hydrogen yield, additional electrodes were inserted between the stack repeating units of ion exchange and bipolar membranes (known as triplets). A techno-economic analysis was carried out by varying the number of electrodes added (i.e., without changing the NaOH production rate). Results appear to be very promising even in the case of a conservative economic scenario. The results show a levelized cost of NaOH of 0.26 € kg-1 NaOH and a net present value of up to 60 M€ for a plant size of 50 m3 h -1 of NaOH.