Simulation-based assessment of oxygen recovery from an AEM electrolyzer using experimental outlet data from a power-to-gas pilot plant

A pilot-scale Power-to-Gas plant powered by hybrid wind-solar energy and equipped with a 2.4 kW anion exchange membrane (AEM) electrolyzer provided the experimental basis for this work. The electrolyzer delivered 250 NL h−1 of oxygen at 0.5 barg and 55°C, yielding 7.28 kg of O2 over 24 h, all previously vented. An Oxygen Recovery System (O2RS) comprising a 50 L buffer, a pneumatic booster, and a 100 L tank pressurized to 35 barg was designed and simulated minute-by-minute across the full cycle. The simulation predicts 99.95% recovery (7 273 g, 3.4 g relieved), a 26.2-fold volume reduction from 4 100 to 156.5 L, and a stored density of 46.5 kg m−3; the tank reaches 35 barg after 14 h 29 min and retains 2 701 g as next-day inventory. Useful isentropic work of 54.2 W against 517.3 W of compressor demand gives 10.55 kWh day−1, a 21.6% overhead on the 48.93 kWh day−1 electrolyzer load and a specific recovery cost of 1.45 kWh kg−1 O2. Hybrid generation covered 38.8% of the 59.47 kWh daily demand; restricting operation to surplus hours reached 100% renewable energy coverage at 41.8% lower yield. These figures position the O2RS as a technically viable pathway for transforming a residual byproduct into a storable resource within renewable hydrogen systems. Physical validation of the proposed design is identified as future experimental work.