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30,000 hours of PEMFC system
operation at a chlor-alkali plant
Stayers: effect of feed contaminants
Oslo, 2-3 April 2013
Jorg Coolegem, Hakan Yildirim, Frank de Bruijn
Membrane MEA Stack System integrators End users
Testing + modeling:
Development & Commercialization:
Goal: > 40.000 hours stationary operation lifetime of PEM fuel cell Motivation: lower replacement frequency PEMFC stacks over economic lifetime Power Plant lower cost of ownership PEMFC Power Plant
Stationary PEM fuel cells with
lifetimes beyond 5 years
Research topics STAYERS project
2
A Components Investigated / Developed (I/D): STA
YER
S
Pre
sen
tati
on
1 membrane D
2 MEA D X
3 catalyst/electrode D
4 GDL I
5 cell plates D
6 seals D
7 BOP I X
• Tower of 2x6 stacks
• 75 cell/stack, 900 cells
• Avg output: 100 A / 600V:
60 kW
• Start: April 2007
• March 2013: Total hours to
grid >33.000
3
System J
[A/cm2] Stoich. ratio
Cathode Stoich. ratio
Anode T stack [deg. C]
RH cathode [%]
RH anode [%]
Power plant Delfzijl
0,5 3.3 2.4 65 85 85
Set up & conditions stack duration test at a chlor-
alkali plant
Operation conditions favorable for durability:
Air
Compression
Air
Humidification
Hydrogen
Humidification
Hydrogen
Recirculation
Air
Exhaust
Coolant
Recirculation
Hydrogen
Vent
DC/AC Grid
Fuel Cells
4
System layout
5
14%
12%
74%
Hydrogen or
pretreated
water supply
unavailable
System up and
running
36%
33%
31%
0%
Electronics
Mechanical
inspection of stacks
Stack
replacement Fuel cell
system
related
downtime
System uptime over period
September 2010 – January 2013
System related downtime System uptime
Compare recent data: uptime 2013 = 97%
BOP very reliable!
0.0
2.0
4.0
6.0
8.0
10.0
12.0
0.0
20.0
40.0
60.0
80.0
0 50 100 150 200 250 300
Sta
ck P
ow
er
[kW
]
Sta
ck v
olta
ge
[V
]
Stack current [A]
Voltage Power
6
Stack characteristics
T stack = 65 °; RH anode and cathode = 80%; P = 1 bara; Stoichiometry H2/air = 1.25/2
7
MEA with low vs. high reversible decay
9
MEA Number of
stacks tested
Typical lifetime
(hrs before stack
voltage has reached
low voltage limit)
Linear cell voltage
decay rate (μV/h)
under 5k MEAs 63 < 5,000 15 to 60
6k MEAs 2 6,000 11 0.3
8k MEAs 9 8,000 6.2 1.3
16k+ MEAs* 8 > 16,000 2.5 0.5
Widespread lifetimes of various MEAs tested
in Pem Power Plant
400
450
500
550
600
650
700
750
800
0 5000 10000 15000 20000
Ave
rag
e c
ell
vo
lta
ge
(m
V)
at 1
20
A
Hours
11
Cell voltage versus time for 8k MEAs
Nedstack’s XXL stacks using 16 k+ MEAs
can operate for more than 20,000 hours
12
Average
cell voltage
mV at 120 A
Hours to grid March 2013:
20,000 hrs
0
100
200
300
400
500
600
700
800
900
1000
0 5000 10000 15000 20000 25000 30000
Decay rate
3 μV/h
Conclusions – good news
1. System is in operation for > 33,000 hours without replacement of
Balance of Plant Components
2. Fuel cell related downtime < 10% readily achievable
3. MEA and stack technology is capable of lasting > 20,000 hours
13
Conclusions - degradation
1. In the PEM Power Plant, conditions are relatively mild:
• Stationary operation, no load cycles, no air/air starts
• Gases are wet (80% RH at inlet)
• Temperature is low (65 °C)
2. Still, many MEAs do not exceed 5,000 hours of operation
3. Reversible decay mainly linked to contaminants
• Accumulation in recycle and long runtimes make even ppb
levels of contaminants relevant
4. Irreversible decay linked to multiple causes:
• Loss of cathode ECSA
• Loss of water removal capability
• Irreversible adsorption of contaminants
14
Contamination determined in air
15
All in ppb (V) Air (Outside) Air (Filter)
NOx 15 15
SO2 1 1
Ammonia <10 <10
Hydrocarbons <10 <10
Remarks:
• NOx difficult to remove
• SO2 also (partially) removed in humidifier/scrubber
SO2 determined in Rainbow-2
16
Cyclic voltamograms of two cells with different MEA’s in same stack
Cathode ECSA reduction seems to correspond with Anode ECSA reduction
0
20
40
60
cell 19 cell 57
ECSA loss compared to BOL
Anode loss (%) Cathode loss (%)
Contamination determined in H2 feed
17
All in ppb (V)
H2 Feed A
H2 recirculation A
H2 Recirculation B
CO 100 70-140 320
CH4 100 170 X
Hydrocarbons X X <10
Chlorine X X <20
S X < 1 X
A, B different analytical labs and different sample moments
X: not checked
Conclusions:
• Presence of CO may result in substantial reversible decay
• No accumulation of CO in recirculation loop?
• CO(g) + H2O(v) → CO2(g) + H2(g) ?
• Origin of CH4?
• Stable component inside recirculation loop?
350
400
450
500
550
600
0:00 1:12 2:24 3:36 4:48 6:00 7:12 8:24 9:36 10:48 12:00
Ce
ll V
olt
age
Time
XXL 1 ppm CO, 200A
Cell voltage loss with 1ppm CO @ 200 A
Cell voltage loss at various CO concentrations
@120A
550
560
570
580
590
600
610
620
630
640
650
0 50 100 150 200
Cell V
olt
ag
e
Minutes
S0213 XXL 120A
no CO
0.2 ppm CO
0.5 ppm CO
1 ppm CO
4 ppm CO
Conclusions
Ranking suspected degradation mechanisms:
1. Cathode loss of active surface area; irreversible
2. Anode loss of active surface area by poisoning; reversible
3. Cathode loss of active surface area by poisoning; reversible
4. Cathode increase of proton resistance; irreversible
Order and extent largely depend on MEA / catalyst formulation
21
Acknowledgements
22
The research leading to these results has received funding from the European
Union’s Seventh Framework Programme FP7/2007-2013 for the Fuel Cels and
Hydrogen Joint Technology Initioative under grant agreement no. 256721
(STAYERS)
See also:
Adriaan J.L. Verhage, Jorg F. Coolegem, Martijn J.J Mulder, M. Hakan Yildirim,
Frank A. de Bruijn, 30,000 h operation of a 70 kW stationary PEM fuel cell
system using hydrogen from a chlorine factory, Int. Journal of hydrogen energy
38 (2013), 4714-4724