Optimal Dynamic Operation of Grid-Integrated Hydrogen Energy System: A Techno-Economic Analysis

Abstract

Rapidly decreasing costs of solar energy and policies that encourage decarbonization are driving solar photovoltaic (PV) farms to be paired with large scale and longer duration energy storage. Hydrogen generation from renewable energy can provide long-term, clean energy storage and can be used in the power industry through fuel cells or combustion turbines, used as chemical feedstock for industry, or as a fuel for transportation. Production costs of hydrogen via electrolytic methods mainly depends on the electricity price, capital costs, and equipment capacity factors. To be cost effective with other types of energy storage, a desired hydrogen price of $1/kg by 2030 will be needed. This study focuses on a techno-economic analysis of a grid-integrated microgrid that includes hydrogen systems (i.e. electrolyzer, compressor, storage tank, and stationary fuel cell), high penetration of solar PV, and battery energy storage systems. The microgrid is operated in a way to minimize the total operation and investment costs and maximize the revenue of the microgrid owner by exchanging power with the grid. While previous work [1] (one hour steady-state time steps) considered a fixed conversion efficiency for the electrolyzer, this study focuses on dynamic operation of the electrolyzer using polarization curves and non-linear conversion efficiency (modeled based on actual cell voltage, cell current, and Faraday efficiency) for more realistic results.Simulation results show that the hourly conversion efficiency of the electrolyzer highly depends on stack operating conditions (cell voltage and current density, the size of the electrolyzer, the temperature, hydrogen demand, etc.). This results in different microgrid optimization and scheduling of energy assets, and consequently the hydrogen production cost. Sensitivity analysis on the PV penetration, current density of the electrolyzer, and changes in asset capital costs will be presented.[1] Hamed Haggi, Paul Brooker, Wei Sun, James M. Fenton, “Hydrogen and Battery Storage Technologies for Low-Cost Energy Decarbonization in Distributed Networks”, arXiv, 11 (2022). https://doi.org/10.48550/arXiv.2202.02711