[ water treatment ]
Fig . 5 . Overview of the water treatment train from raw water to ultrapure water suitable for electrolysis
gasses such as CO 2
. These must therefore be removed with a dedicated process . For a chemical-free option , a membrane degasser can be installed after the RO membrane . Alternatively , lye can be dosed in front of the membranes to convert CO 2 to bicarbonate ions that can be removed with the RO system . To reach the very low conductivities required by many electrolysers , a final deionization is required . Here , either a mixed bed filter or an electrodeionization ( EDI ) unit can be used . These processes will take any remaining ions and exchange them for H + and OH- ions . The mixed bed must be regenerated or exchanged once spent , while the EDI can operate continuously due to a self-regenerating design . Often the two deionization technologies will be employed together with the mixed bed placed as a ‘ police filter ’ after the EDI .
Case – Everfuel
One specific example of water treatment for green hydrogen production is the HySynergy project by Everfuel . Consisting of three phases – 20 MW ( 2022 ), 300 MW ( 2025 ) and 1 GW ( 2030 ),
Figure 5 illustrates this general process configuration , while Figure 6 shows an example of such a system .
Fig . 6 . Frame-mounted water treatment system for production of water suitable for electrolysis (< 0.1 µ S / cm ). This system has a capacity of 1 – 2 m 3 / h equal to an electrolyser capacity of 5 – 10 MW .
Hydrogen Tech World | Issue 6 | October 2022 27