Optimal design of on-site PV-based battery grid-tied green hydrogen production system

Abstract

Green hydrogen (H2) is among the most promising energy vectors that may enable the decarbonization of our society. Nonetheless, the design of the green H2 production system is challenging and requires accurate simulation of the system for effective optimization. This study presents a mixed-integer linear programming (MILP)-based optimization framework for optimizing grid-tied PV-based battery H2 production systems. The results are showcased using a set of environmental, technical, and economic metrics to provide a universal guide for the design of green H2 production system that goes beyond examining specific case studies. The analysis focuses on Thailand and specifically examines the influence of grid electricity prices on the H2 production system. The findings from the study suggest that the cost of grid electricity significantly influences the design of the green H2 production system. More precisely, when the cost of electricity is high, it is profitable to increase the size of both the PV system and electrolyzer (EL). The PV ratio, which is the ratio of the PV system to the EL increases from 2.2 to 2.9 when the electricity price increases from USD 20 to 220/MWh. Furthermore, when grid energy prices surpass USD 120/MWh, the capacity of the EL increases by nearly three times compared to the H2 demand. The comparison of off-grid and grid-tied green H2 production system demonstrates the significance of grid electricity; despite being used inefficiently, the grid still plays a vital role in minimizing the capacity of H2 storage. Based on the grid energy price, the cost of H2 from USD 3.7–6.5/kg for the grid-tied green H2 production system, and USD 7.6/kg for the off-grid H2 system. Finally, H2 carbon footprint, measured in kg CO2, e/kg H2 is investigated.