Green hydrogen production: Energy, exergy, exergoeconomic and exergoenvironmental perspectives using solid oxide electrolysis cells

Hydrogen production is commonly achieved through water electrolysis, with the solid oxide electrolysis cell (SOEC) being the most efficient technology. The SOEC is powered by both electricity and thermal energy in the form of high-temperature steam. In this study, an electrolyzer system was designed to operate with 3 MW of electricity and steam at 880 °C. Electricity is supplied by photovoltaic (PV) modules supported by battery banks, while a heliostat solar field and hot and cold storage tanks provide the required steam. Energy, exergy, exergoeconomic, and exergoenvironmental assessments are carried out for the system. The lowest daily exergy efficiency was observed in the PV panels (18.06%). The specific cost and environmental impact of hydrogen production are 10.95 US$/kg and 459 mPt/kg. Oxygen presented a specific cost of 0.0447 US$/kg and an environmental impact of 0.595 mPt/kg. The exergoeconomic assessment indicated that PV panels and battery banks exhibited the highest total cost rates, 1623 US$/h (related to the cost rates of their components and exergy destruction). The battery bank also accounted for the highest environmental impact of components within the global system as 77.42%, while PV panels and batteries together displayed the highest total environmental impact rate corresponding to 97.91%. Improvement opportunities were identified primarily in electricity supply and storage subsystems.