Conference Agenda - European Fuel Cell Forum

10 th European SOFC Forum 26 - 29 June 2012, Lucerne Switzerland
A1109
Modeling and Design of a Novel Solid Oxide Flow
Battery System for Grid-Energy Storage
Chris Wendel and Robert Braun
Department of Mechanical Engineering
College of Engineering and Computational Sciences
Colorado School of Mines
1500 Illinois St., Golden, CO, USA
Tel.: +001 (303) 273-3055
cwendel@mines.edu; rbraun@mines.edu
Abstract
Viable electric energy storage (EES) solutions are recognized as an important area of
development for the energy grid of the future. A solid oxide flow battery (SOFB) concept
utilizing a reversible ceramic based solid oxide cell (SOC) stack as the working component
is proposed for EES applications. The SOFB system converts electricity to chemical
energy (charges) by electrolyzing H2O and CO2 feed gases into a fuel-rich mixture of H2,
CO, CH4 which is stored for later use. The SOFB discharges in fuel cell mode by
converting the chemical energy of the stored fuel mixture back into electricity through
electrochemical oxidation. A thermodynamic system level model is presented, including
balance of plant components (compressors, heat exchangers, and storage tanks), to
assess system design concepts and overall SOFB performance. It is shown that
increasing the stack operating pressure and nominal cell temperature increase roundtrip
efficiency. With the SOFB cell-stack operating at 20 bar, 750°C, and an economically
favorable fuel cell power density of 0.37 W/cm 2 , the model predicts a roundtrip efficiency of
almost 66%. The roundtrip efficiency is improved to nearly 75% when the area specific
resistance (ASR) is lowere�����������-cm 2 , while maintaining a high power density (0.39
W/cm 2 ).
SOE cell and stack operation Chapter 09 - Session A11 - 9/9
10 th European SOFC Forum 26 - 29 June 2012, Lucerne Switzerland
A1201
Chemical Degradation of SOFCs:
External impurity poisoning and
internal diffusion-related phenomena
Kazunari Sasaki (1) (2) (3) (4), Kengo Haga (3), Tomoo Yoshizumi (3),
Hiroaki Yoshitomi (3), Kota Miyoshi (3), Shunsuke Taniguchi (1) (2),
Yusuke Shiratori (1) (2) (3) (4)
Kyushu University,
(1) Next-Generation Fuel Cell Research Center
(2) International Research Center for Hydrogen Energy
(3) Faculty of Engineering,
(4) International Institute for Carbon-Neutral Energy Research (WPI-I2CNER)
Motooka 744, Nishi-ku
Fukuoka 819-0395 / Japan
Tel.: +81-92-802-3143
Fax: +81-92-802-3223
sasaki@mech.kyushu-u.ac.jp
Abstract
Durability of SOFCs is one of the most important requirements for their commercialization.
In this paper, we analyze chemical degradation phenomena caused by both extrinsic and
intrinsic origins. As external degradation, impurity (sulfur, phosphorus, boron etc.)
poisoning has been systematically analyzed and classified. Such impurities could be
introduced from practical fuels, system components, as well as inexpensive raw materials.
In addition, we present typical intrinsic chemical degradation phenomena observed, mainly
diffusion-related processes (interdiffusion, grain boundary diffusion, dopant dissolution,
phase transformation etc.), around interfaces between the electrolyte and the electrode,
which has been revealed through high-resolution STEM-EDX (Scanning Transmission
Electron Microscope - Energy-Dispersive X-ray analyzer) analysis of cells after long-term
tests. Importance of academia-industry collaborations is discussed.
Cell and stack operation Chapter 10 - Session A12 - 1/18