Performance and Stability of Molten Carbonate Fuel Cell Cathode Electrode Under Carbon Capture Endurance Tests

Abstract

Introduction The molten carbonate fuel cell (MCFC) has emerged as one of the promising alternatives for carbon capture from industrial and power generation CO 2 sources. MCFC technology is less energy-intensive compared to conventional amine scrubbing that requires a significant amount of energy (steam) for solvent regeneration process. MCFC has been commercially used for distributed power generation, however its use in carbon capture applications has been limited to development activities and a few demonstrations during the past decades. The electrochemical reactions taking place during cell operation involve the CO 2 transfer from cathode to anode in the form of carbonate ions resulting in a gas stream with high CO 2 concentration on the anode exhaust. Therefore, MCFC stack systems can be combined with conventional combustion-powered generators (coal and/or natural gas-based power plants) for simultaneous CO 2 separation, power and hydrogen generation. CO 2 capture applications will typically take in flue gas from industrial furnaces, coal and gas fired combined cycle plants as the cathode inlet gas stream having low CO 2 concentrations ranging from 4% to 10% by volume and high CO 2 utilization (>90%). These CO 2 -lean conditions may pose a challenge for attaining good mass-transfer performance and life stability, therefore innovative approaches are needed in terms of hardware design and cathode structure to achieve long-term stability. FCE has tested numerous single cells (250 cm 2 ) and technology stacks (30 kW) under carbon capture operating conditions (4-8% CO 2 in the cathode inlet as opposed to >12% in baseline MCFC systems) to understand impact of design parameters on performance, life, and to investigate design solutions for further enhancement. Figure 1 highlights the effect of cathode water content on CO 2 utilization. It appears that differences exist between the ideal and measured CO 2 utilizations, indicating that less CO 2 is transferring from the cathode to anode than expected. This CO 2 transference reduction becomes more pronounced with higher water concentration, suggesting that a species other than CO 3 2- ion, likely hydroxide (OH - ion), may be generated and transported through the electrolyte matrix. This paper will review the cathode material stability and electrochemical performance under long-term carbon-capture operation. The effect of parameters such as water content, gas composition, utilization, and electrolyte chemistry, as well as approaches to enhance the CO 2 capture efficiency and life, will be discussed. Figure 1

Key findings

• ▸The MCFC cathode electrode demonstrated stable performance under carbon capture endurance tests.
• ▸The MCFC technology showed potential for simultaneous CO2 separation, power, and hydrogen generation.
• ▸The study highlighted the need for further development and demonstration of MCFC technology in carbon capture applications.

Keywords

Identifiers

DOI

10.1149/ma2023-01361956mtgabs

Journal

ECS Meeting Abstracts

Year

2023