Renewables and Grid-Energy Storage Systems

Efficient Reversible Operation and Stability of Novel Solid Oxide Cells

Electrical energy storage is expected to be a critical component of future energy systems, performing load-leveling operations to enable increased penetration of renewable and distributed generation. The U.S. Department of Energy (DOE) recently published long-term targets for grid energy storage of high roundtrip efficiency, 150 $/kWh capital cost and 10 cent/kWh-cycle levelized cost to fulfill energy management applications like energy time-shifting, transmission and distribution upgrade deferral, and customer energy management services. Reversible solid oxide cell (ReSOC) systems are a novel technology that may be able to meet the DOE criteria.

A reversible solid oxide fuel cell (ReSOC) is a device that can operate efficiently in both fuel cell and electrolysis operating modes. Thus, in the fuel cell mode, ReSOC generates electricity by electrochemical combination of a fuel (hydrogen, hydrocarbons, alcohols, etc.) with oxygen in the air. In the electrolysis mode, ReSOC functions as an electrolyzer, producing hydrogen from water or chemicals such as syngas (from mixtures of water and carbon dioxide) when coupled with an energy source (fossil, nuclear, renewable). Fig. 1 illustrates the operating principles of the ReSOC.

operating principles of an ReSOC

Fig. 1 Operating principles of an ReSOC (written for hydrogen fuel in SOFC mode and steam electrolysis in SOEC mode).

This 3-year project funded by the DOE will allow research and validation of novel reversible solid oxide cell (ReSOC). The DOE funding will specifically focus on ReSOC cells and operating conditions that yield very low cell area specific resistance (ASR), and cells that have low degradation at relatively high current density. Furthermore, it will put a focus on new cell designs, larger-area cells, and cell operation on pure oxygen. Much of our prior work on degradation during ReSOC operation has focused on lower operating temperatures; here the focus will be on higher temperatures where low ASR’s are obtained. The modeling and system-level studies will establish cell/system design requirements and identify ReSOC system configurations that enable ≥65% RTE at levelized energy costs that are competitive with leading battery technologies.

The Advanced Energy (AES) group has for several years collaborated with Dr. Barnett’s research group at Northwestern University to address these challenges. For this current project Barnett’s team is focusing on to improve cell performance and manufacturing techniques, whereas the AES group’s primary effort is in the development of system level concepts for deploying ReSOC with cost effective energy storage devices. This includes investigation of thermal energy storage, system integration, and techno-economic analysis of these systems.

System Design and Modeling

While the focus of the proposed project is significantly aimed at SOC materials and cell development, the system modeling will be used to interject critical feedback into the ReSOC materials/cell development process by providing a holistic viewpoint that is cognizant of systems-level considerations. These considerations include storage pressure, stack pressure, water and thermal management strategies, reactant utilization, and balance-of-plant constraints that are crucial to realizing ≥65% RTE. Figure 2 illustrates one proposed ReSOC system concept in which stack exhaust gas thermal energy is recuperated for preheat of reactant gases and optionally, for charge/discharge of thermal energy storage (TES) in fuel cell/electrolysis modes.

proposed ReSOC system concept

Fig. 2 Oxygen- / air-breathing ReSOC system concept with optional thermal energy storage (TES).

System scale-up and techno-economic analysis (TEA) shall be performed to establish capital and operating costs, and to assess the potential of the technology compared to competing energy storage technologies. Tasks related to TEA will focus on establishing system design and Nth generation costs for two target storage markets: (i) light commercial (40–200 kWh energy; 5–25 kWe), such as utility-owned community energy storage, and distributed PV integration, and (ii) commercial/light industrial (1 MWh–10 MWh energy; 100kW–1 MWe). Detailed cost models will be generated to enable system capital and levelized storage cost estimation. The results from this will support techno-economic optimization and scale-up studies, as well as provide the framework for risk reduction assessment at end of project.

Scale-up approach

Fig. 3 Scale-up approach from cells to systems

FUNDING: DOE

Current Projects

Past Projects

Selected Publications in This Research Area

Simulation of the Supercritical CO2 Recompression Brayton Power Cycle with a High-Temperature Regenerator

E.P. Reznicek, J.F. Hinze, G.F. Nellis, M.H. Anderson, R.J. Braun

Energy Conversion and Management, 229:1113678, (2021)

One-Dimensional, Transient Modeling of a Fixed-Bed Regenerator as a Replacement for Recuperators in Supercritical CO2 Power Cycles

E.P. Reznicek, J.F. Hinze, L.M. Rapp, G.F. Nellis, M.H. Anderson, R.J. Braun

Energy Conversion and Management, 218:112921 (2020)

Simulation of sCO2 Recompression Brayton Cycles with Regenerators

E. Reznicek, R.J. Braun

Proceedings of the 6th International Supercritical CO2 Power Cycles Symposium (2018)

Simulation of Supercritical Carbon Dioxide Brayton Recompression Cycles with Regenerative Heat Exchangers

E. Reznicek, R.J. Braun

Proceedings of the ASME 2017 11th International Conference on Energy Sustainability, 3946 (2017)

Optimized Dispatch in a First-Principles Concentrating Solar Power Production Model

M.J. Wagner, A.M. Newman, W.T. Hamilton, R.J. Braun

Applied Energy, 203:959–971, (2017)

Modeling and Simulation of Regenerative Heat Exchangers for Supercritical CO2 Cycles

E. Reznicek and R.J. Braun

Proceedings of the ASME 2016 10th International Conference on Energy Sustainability, 59869 (2016)

A Thermodynamic Approach for Selecting Operating Conditions in the Design of Reversible Solid Oxide Cell Energy Systems

C. Wendel, P. Kazempoor, R.J. Braun

Journal of Power Sources, 301:93–104, (2016)

Large-Scale Electrical Energy Storage Utilizing Reversible Solid Oxide Cells Combined with Underground Storage of CO2 and CH4

S.H. Jensen, C. Graves, M. Mogensen, C. Wendel, R.J. Braun, G. Hughes, Z. Gao, S.A. Barnett

Energy and Environmental Science, 8:2471–2479, (2015)

Novel Electrical Energy Storage System Based on Reversible Solid Oxide Cells: System Design and Operating Conditions

C. Wendel, P. Kazempoor, R.J. Braun

Journal of Power Sources, 276:133–144, (2015)

Modeling and Experimental Performance of an Intermediate Temperature Reversible Solid Oxide Cell for High Efficiency, Distributed-Scale Electrical Energy Storage

C. Wendel, R.J. Braun

Journal of Power Sources, 283:329–342, (2015)

Thermodynamic Analysis of Non-Stoichiometric Perovskites as a Heat Transfer Fluid for Thermochemical Energy Storage in Concentrated Solar Power

K.J. Albrecht, R.J. Braun

Proceedings of the ASME 2015 9th International Conference on Energy Sustainability, 49409 (2015)

Model Validation and Performance Analysis of Regenerative Solid Oxide Cells: Electrolytic Operation

P. Kazempoor, R.J. Braun

International Journal of Hydrogen Energy, 39:2669–2684, (2014)

Model Validation and Performance Analysis of Regenerative Solid Oxide Cells for Energy Storage Applications: Reversible Operation

P. Kazempoor, R.J. Braun

International Journal of Hydrogen Energy, 39:5955–5971, (2014)

View Other Research Areas:

HIGH-TEMPERATURE FUEL CELLS FOR MOBILE AND STATIONARY APPLICATIONS

MODELING AND SYSTEMS ANALYSIS OF ALTERNATIVE FUEL PRODUCTION AND UTILIZATION SYSTEMS