Date of Award

8-16-2024

Document Type

Open Access Dissertation

Department

Mechanical Engineering

First Advisor

Kevin Huang

Abstract

Long-duration energy storage (LDES) (10+ hours) is considered a key technical solution for a widespread penetration of renewable energy into the utility market. However, the currently available storage technologies are limited to less than 10 hours for cost reasons. The benchmark Li-ion battery technology would be economically prohibitive if the storage time goes beyond 4 hours. Therefore, developing new low-cost LDES-compatible battery technologies is highly desirable. A solid oxide iron air battery (SOIAB) has been developed which consists of a reversible solid oxide cell (RSOC) and energy storage unit (ESU) of an iron bed. This battery is considered a promising candidate for LDES application due to its excellent low-rate performance (high capacity with high efficiency) and use of low-cost and sustainable ESU materials. In the first part of this PhD Work, a systematic kinetic study of Fe3O4-to-Fe reduction in H2/H2O environment, particularly the effect of catalyst (Iridium) and supporting oxides (ZrO2 and BaZr0.4Ce0.4Y0.1Yb0.1O3) under different concentrations of H2 at intermediate temperatures (500-575oC). With in situ created Fe3O4, the degree of reduction is measured by the change of H2O and H2 concentrations in the effluent using a mass spectrometer, from which the kinetic rate constant is extracted as a function of inlet H2 concentration and temperature. We find that kinetics can be nicely described by Johson-Mehl-Avrami (JMA) model, showing three stages of reduction. The activation energy of both (ZrO2 and BZCYYb) based materials experiences a “peaking” behavior against reduction extent. By adding Ir catalyst and using proton containing supporting oxides in the baseline ESU, a significantly boosted kinetics has been observed. The activation energy of Fe3O4/ZrO2-Ir and Fe3O4/BZCYYb-Ir is higher than baseline, implying that the high pre-exponential factor (A) must be the reason for boosted kinetics. In the second part of this PhD work, a high-fidelity two-dimensional axial symmetrical multi-physics model has been developed to simulate the cycle performance of a SOIAB for baseline (Fe2O3/ZrO2), Fe2O3/ZrO2-Ir and Fe2O3/BZCYYb-Ir energy storage material. The model considers mass transport, charge transport, and chemical redox kinetics cycle occurring within a battery and is validated with experimental data from independent studies. The H2/H2O molar fraction, Nernst potential, current density in RSOFC and mass flux equivalent current density in ESU of a battery has been simulated. In addition, the effects of current density, iron utilizations, kinetic rate constant, and exchange current density have been simulated by the developed model. In the third part of the thesis, Techno-Economic Assessment (TEA) was performed to project the potential of the SOIAB system for LDES. A SOIAB system consists of subsystems of RSOFC, ESU, balance of plant (BOP), and power conversion system (PCS). The study is focused on analyzing the cost of the SOIAB system under various scenarios. The analysis includes capital cost and levelized cost of electricity (LCOE) of the SOIAB system operated under 50, 100, 200 and 500-kW and different discharging duration (10-500 hours). Using the estimated capital cost, an economic model was established to calculate LCOE for the system. With the DOE’s LCOE as $0.05/kWh/cycle for LDES as a target, different case studies have been performed, including current density, ESU porosity, and iron utilizations, to identify the best conditions to meet the DOE’s cost target. It is found that Iridium (Ir) catalyst cost dominate the overall cost of the system. Therefore, reducing Ir loading and increasing ESU utilization are two of the most effective means to lower the system cost.

Rights

© 2024, Chaitali Morey

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