Hydrogen produced by electrolysis will play an important role in our future energy systems.

At electrolysis, water (H2O) is split into Hydrogen (H2) and Oxygen (O2) with electric energy.

The requirements with respect to water supply and waste discharge quality and water quantity are challenging.

The water supplied to the electrolyzer needs to be free of suspended matter and low in dissolved compounds. The process waste needs to be fit for discharge.

The production of 1 kg of H2 with PEM electrolysis requires (numbers and diagram taken from Brannock et al., Proceedings of the IDA World Congress 2022, Sydney):

• Supply of 10kg highly demineralized water
• Supply of 35kg low salinity water for cooling
• Discharge of 23.5kg wastewater with elevated salinity (if tap grade water is used as raw water. Higher raw water pollution results in higher wastewater flows)

UNIHA provides integrated solutions to produce electrolyzer feed and cooling water with our tailor-made Reverse Osmosis, Degasification and Electrodeionisation units. On the wastewater side, we offer reuse treatment up to Zero Liquid Discharge solutions.