Enhanced Performance and Durability of a High Temperature Steam Electrolysis Stack

Abstract

High temperature steam electrolysis (HTSE) is one of the most promising ways for hydrogen mass production. If coupled to a CO2‐free electricity and a low cost heat source, this process is liable to a high efficiency. High levels of performance and durability, in association with cost‐effective stack and system components are the key points. To reach such goals, a low‐weight stack has been designed, keeping the advantages of the high performing and robust stack previously validated in terms of performance, durability, and cyclability [1], but aiming at reducing the cost by the use of thin interconnects. This low‐weight stack has demonstrated at the scale of a 3‐cell stack a good performance of –1.0 A cm–2 at 1.3 V at 800 °C. Before performing the durability test, preliminary studies at the cell level have been carried out to highlight the effect of two major operating parameters that are the current density and the steam conversion (SC) ratio, those studies being carried out at one temperature, 800 °C. Based on these results, optimized operating parameters have been defined to perform the durability test on the stack, that is –0.5 A cm–2 and a SC ratio of 25%. Degradation rates around 3–4% 1,000 h–1 have been measured. The thermal cyclability of this stack has also been demonstrated with one thermal cycle. Therefore it can be concluded that these results make HTSE technology getting closer to the objectives of performance, durability, thermal cyclability, and cost.

Hydrogen production by high-temperature steam electrolysis

“…Values of À1 A/cm 2 at 1.3 V at 850 C were reported by Hauch et al in 2008 with LSM oxygen electrodes (Hauch, Ebbesen, Jensen, & Mogensen, 2008). The same current density can be achieved at 800 C owing to the use of LSCF oxygen electrodes (Brisse, Schefold, & Zahid, 2008;Mougin et al, 2013). Current densities as high as À2.0 A/cm 2 or even higher can be achieved at thermoneutral voltage at 800 C with advanced CSC cells; the major difference is the use of an LSC oxygen electrode (Figure 8.9).…”

Development of a Cost-Efficient and Performing High Temperature Steam Electrolysis Stack

“…A current density of -1 A·cm -2 is still achieved at 700°C at the thermo-neutral voltage, showing that the cell and stack considered can still be operated at high current density for lower temperature, which can be useful to preserve the materials from severe ageing. They appeared at 700°C even better than the same stack with so-called reference cells at 800°C (12).…”

Unitized Regenerative Systems

“…Details about cells based on LSM oxygen electrode operating at 850 ∘ C at 1 A cm −2 and 1.3 V have been reported in 2008 in the literature [9]. Using LSCF oxygen electrodes, the same current density can be achieved but at only 800 ∘ C [10,11]. Current densities as high as −2.0 A cm −2 or even above can be achieved at the thermoneutral voltage at 800 ∘ C using advanced CSC cells ( Figure 5.15).…”

“…11 Polarization curves of a low-temperature URFC for different catalyst compositions at 80 ∘ C[1]. 12 Typical plots of the efficiency of PEM water electrolysis cell, fuel cell and URFC as a function of operating current density, at 80 ∘ C.…”