Abstract: ​L​ow-cost, high efficiency, electrical energy storage (EES) is needed for the future electric grid which will include more variable energy resources, such as wind and solar. Movement towards predominately low-carbon energy systems requires renewable resources and could be accelerated by integration of high temperature electrochemical technologies. Currently, substantial penetration of wind and solar resources into the electric power grid is challenged by their intermittency and the timing of generation which can place huge ramping requirements on central utility plants, which are also limited in dynamic response capability. This talk will discuss employing novel EES systems derived from reversible fuel cell technology and advances in protonic ceramics as dispatchable energy resources. Reversible solid oxide cells (ReSOCs) are capable of providing high efficiency and cost-effective electrical energy storage. These systems operate sequentially between fuel-producing electrolysis and power-producing fuel-cell modes with storage of reactants and products (CO​2/​ CH​4g​ ases) in tanks for smaller-scale (kW) applications and between grid and natural gas infrastructures for larger scale (MW) systems. In this talk, the use of ReSOC technology for both grid-scale energy storage and as a Power-to-Gas platform that can address issues with high renewables penetration is presented. In stand-alone systems, strategies for effective thermal management and balance-of-plant systems integration in both operating modes are critical to achieving high roundtrip efficiencies. Design challenges and techno-economic analyses which suggest levelized cost of storage that ranges between 15 – 30 $/MWh are highlighted. A brief overview of recent progress in the performance of intermediate temperature (500-600°C) protonic ceramic fuel cells (PCFCs) which have demonstrated both fuel flexibility and increasing power density that approach commercial application requirements will also be given. The PCFCs investigated in this work are based on a BaZr​0.8Y​ ​0.2O​ ​3-δ(​ BZY20) thin electrolyte supported by BZY20/Ni porous anodes, and a triple conducting cathode material comprised of BaCo​0.4F​ e​0.4Z​ r​0.1Y​ ​0.1O​ ​3-δ(​ BCFZY0.1). Performance characteristics, modeling challenges, and techno-economic outlook of mixed-charge conducting PCFCs are presented.

Biographical Sketch: ​Dr. Robert Braun is Associate Professor of Mechanical Engineering at the Colorado School of Mines. He received a Ph.D. from the University of Wisconsin–Madison in 2002. From 2002-2007, Dr. Braun was at United Technologies Fuel Cell and Research Center divisions where he last served as project leader for UTC’s mobile solid oxide fuel cell (SOFC) power system development program. Dr. Braun has multidisciplinary background in mechanical and chemical engineering and his research focuses on energy systems modeling, analysis, techno-economic optimization, and numerical simulation of transport phenomena occurring within fuel cell and alternative energy systems. His industry experience encompasses development of low-NOx burners, CO​2-​ based refrigeration, and fuel cell technologies (including PEM, PAFC, MCFC, SOFC, and PCFC). Dr. Braun’s current research activities focus on high efficiency hybrid fuel cell/engine systems, renewable energy pathways to synthetic fuel production, grid-scale energy storage, novel protonic ceramics, supercritical CO​2 p​ ower cycles, and dispatch optimization of concentrating solar power plants. He is a Link Energy Foundation Fellow, a member of ASME, ECS, and ASHRAE, and holds 6 U.S. patents.