Dynamic Sub-Thermoneutral Voltage Operation of Solid Oxide Electrolysis with Alternative Heat Addition

Abstract

In this study, we experimentally evaluated electrolysis of water using a short stack of six solid oxide electrochemical cells (SOEC). A model of the SOEC stack was verified and used to evaluate thermal management of the stack operating above and below the thermoneutral voltage, which at these temperatures requires additional heat input into the stack to maintain the system operating temperature. High quality heat was supplied from a molten salt. Heat generated from concentrated solar power (CSP) can reach the required SOEC operation temperature through molten salts and can provide enough heat to sustain sub-thermoneutral voltage operation of an SOEC. The SOEC model is spatially and temporally resolved and was used to evaluate the dynamic performance of a system operating at sub-thermoneutral voltages with dynamic heat input. Dynamic results suggest high efficiency hydrogen generation can occur with external heat input under various conditions including variable power and salt flow.

Thermal Behavior and Performance Trajectories of Electrolysers

“…There have been recently interesting efforts [23][24][25] for improved heat addition and heat conduction, such as resistive heaters (herein R3) in a sealed tube with a stack for rapid fire-up, and molten salt mixtures used as the heat exchanger transfer medium for pre-heating SOEC fuel. The heat process could be also conducted with concentrating solar for renewable applications.…”