Operating Principles, Performance and Technology Readiness Level of Reversible Solid Oxide Cells

Abstract

The continuous increase of energy demand with the subsequent huge fossil fuel consumption is provoking dramatic environmental consequences. The main challenge of this century is to develop and promote alternative, more eco-friendly energy production routes. In this framework, Solid Oxide Cells (SOCs) are a quite attractive technology which could satisfy the users’ energy request working in reversible operation. Two operating modes are alternated: from “Gas to Power”, when SOCs work as fuel cells fed with hydrogen-rich mixture to provide both electricity and heat, to “Power to Gas”, when SOCs work as electrolysers and energy is supplied to produce hydrogen. If solid oxide fuel cells are an already mature technology with several stationary and mobile applications, the use of solid oxide electrolyser cells and even more reversible cells are still under investigation due to their insufficient lifetime. Aiming at providing a better understanding of this new technological approach, the study presents a detailed description of cell operation in terms of electrochemical behaviour and possible degradation, highlighting which are the most commonly used performance indicators. A thermodynamic analysis of system efficiency is proposed, followed by a comparison with other available electrochemical devices in order to underline specific solid oxide cell advantages and limitations.

Classification of Solid Oxide Fuel Cells

“…Another noteworthy concept is reversible SOFC (RSOFC or RSOC), which implies that a solid-state electrochemical device can operate both in the fuel cell mode and in the electrolysis mode [ 159 , 160 ]. In the first mode, RSOFC operates on the SOFC principle converting fuel into electricity.…”

“…As in the case of SSOFC, RSOFC can be implemented in any separate-reactant SOFC design. Today, pilot plants of RSOFC are already being tested [ 160 ]. However, a number of problems still need to be solved for the commercialization of RSOFC: an exact understanding of cell behavior and its degradation when switching modes, the selection of materials and operating parameters suitable for reversible operation, a connection of RSOFC to existing networks, and reducing the cost.…”

Optimal Management of Renewable Generation and Uncertain Demand with Reverse Fuel Cells by Stochastic Model Predictive Control

“…and constraints are ( 1)-( 11), ( 15)-( 16), (23). Constraints that involve random variables are (15) and (16). Therefore, first we rewrite (15) as equality constraint, ∀k ∈ [0, T − 1]:…”

Challenges of Fuel Cell Technologies for the Needs of the Energy Transition to a Zero-carbon Technology

“…As for SOFC, the high temperatures (700-900 °C) of the ceramic electrolysis cell (SOEC) provide high efficiency, namely up to 98 %. There are other electrolyze technologies of this type on the market [10]. Like the fuel cells, electrolyzers can be divided by the type of electrolyte.…”