Energy-environmental analysis of an H2PEM power station assisted by a dynamic simulation tool

Abstract

This paper reports on the development of a numerical tool tailored to perform energy and environmental analyses for an H2PEM power station, comprising fuel cell and electrolysis units, with a dual-mechanism H₂ storage that incorporates compression and metal hydride tanks. A comprehensive methodology for the design, modeling, and simulation is introduced, focusing on the interaction of the H2PEM with a higher-level network that exchanges electrical power. The H2PEM is 1 kW level, with a H₂ storage capacity of 5 Nm³. The work stands out for the modeling of subsystem interconnections under a strategic operational plan, offering an integrated understanding of system behavior. The modeling includes temperature regulation, encompassing the assessment of heat management, as well as that of the auxiliaries. Steady state and dynamic simulations are conducted within the Matlab/Simulink computational environment to assess the performance under various conditions. The energy and environmental analyses comprise determining key parameters such as involved energies, hydrogen production and consumption, state of charge of the hydrogen reservoir, CO₂ emissions and savings, and associated temperature changes. Three case scenarios are assessed, considering H2PEM interacting with a network powered by: (1) solely fossil-based electricity, (2) the Italian energy mix for 2023, and (3) entirely renewable energy sources. Results revealed nominal efficiency of 55% for the electrolyzer and 40.5% for fuel cell. About 1 order of magnitude of CO₂ is saved when the H2PEM is totally renewable (93.36 vs. 1.539 kg_CO2 kg_H2⁻¹). The temperature increase associated is 10.5 × 10⁻³ °C per ppm of CO₂ emitted.