Utilizing oxygen from green hydrogen production in wastewater treatment plant aeration: A techno-economic analysis

The growing demand for green hydrogen is driving the expansion of water electrolysis. The resulting oxygen byproduct offers potential added value when used in sectors with high oxygen demand, such as wastewater treatment. This study investigates the techno-economic viability of using electrolysis oxygen to supplement conventional air blowers in the aeration process of municipal wastewater treatment plants (WWTPs) to reduce aeration costs and thereby improve the overall economics of hydrogen production. A comprehensive system model is developed, incorporating renewable electricity supply, water electrolysis, hydrogen compression, storage, and transport, as well as WWTP aeration via conventional air blowers and electrolysis oxygen. Results show that electrolysis oxygen can reduce WWTP aeration costs by up to 68%. If these cost reductions are attributed as a benefit to the hydrogen system, they correspond to hydrogen supply cost savings of up to 0.39 EUR/kgH₂. However, the analysis indicates that economic viability is substantially influenced by factors such as the distance of hydrogen transport from the WWTP to the European Hydrogen Backbone feed-in point, which should not exceed 25 km, and the alignment between the scale of hydrogen production and the size of the WWTP, with cost-effective integration being particularly feasible for larger WWTPs (≥500,000 PE).