Nuclear Production of Hydrogen, Fourth Information Exchange ...

HIGH-TEMPERATURE STEAM ELECTROLYSIS FOR HYDROGEN PRODUCTION: FROM MATERIAL DEVELOPMENT TO STACK OPERATION
Figure 4: Durability test at 820°C; evolution of cells’ voltages
over 406 hours, with a current of 36 A applied on the stack
1.80
E (V)
1.70
1.60
1.50
cell 1
cell 2
cell 3
1.40
1.30
1.20
0 50 100 150 200 250 300 350 400
Time (h)
Table 2: Degradation rate calculated from the curves presented in Figure 4 for the three cells
U
(t = 0)
U
(t = 406 h)
Degradation
ΔV/1 000 h
Degradation
%/1 000 h
Cell 1 1.40 1.67 0.677 49
Cell 2 1.24 1.29 0.123 10
Cell 3 1.33 1.52 0.468 35
high degradation rates in HTSE operation mode (Hartvigsen, 2007; Mawdsley, 2008; O’Brien, 2007). For
Cell 1 and Cell 3, the durability curve is not linear over the period. In particular a shift in voltage is
observed around 200 hours on the Cell 1 curve. It was associated with a temperature increase on the
stack, which could reflect a crack in the cell, consistent with the fact that this cell was found cracked
when the stack was opened after the end of the test.
SRU performances
Performances obtained at 800°C on the SRU with a Ni-CGO/TZ3Y/LSCF electrolyte supported cell are
reported in Figure 5 and in Table 3.
Depending on the cathodic inlet gas mixture, ASR between 0.77 and 0.86 Ω.cm 2 were obtained.
Hydrogen productions between 18.7 and 20.9 mg/cm 2 /h were achieved at 1.3 V, which were increased
to 26.2 to 29.9 mg/cm 2 /h when a voltage of 1.5 V was considered. These productions corresponded to a
steam utilisation rate between 62 and 39% at 1.3 V and between 87 and 55% at 1.5 V, respectively.
It can be noted that the lowest target set by the RelHy project in terms of hydrogen production
was 30 mg/cm 2 /h. This target was achieved according to the results reported at 1.5 V and for the
cathodic inlet gas with the highest steam concentration.
Performances on single cells containing nickelate oxygen electrode
Current-voltage curves recorded on a single cell containing the Nd 2 NiO 4+δ oxygen electrode is given in
Figure 6 for the three temperatures 750, 800 and 850°C. For comparison i-V curves measured on the
same cell but containing classical LSM oxygen electrode are also reported. i-V measurements highlight
124 NUCLEAR PRODUCTION OF HYDROGEN – © OECD/NEA 2010