unitized regenerative fuel cells for hydrogen energy...
TRANSCRIPT
H. Ito, Japan-Norway Energy Science Week 2015, 28 May 2015, Tokyo H. Ito, Japan-Norway Energy Science Week 2015, 28 May 2015, Tokyo 1
Unitized Regenerative Fuel Cells for
Hydrogen Energy Storage Systems
Japan-Norway Energy Science Week 2015
Hiroshi Ito, Akihiro Nakano
National Institute of Advanced Industrial Science and Technology (AIST)
Naoki Miyazaki, Masayoshi Ishida
University of Tsukuba
H. Ito, Japan-Norway Energy Science Week 2015, 28 May 2015, Tokyo H. Ito, Japan-Norway Energy Science Week 2015, 28 May 2015, Tokyo 2
Outline
1. Background / Scope
2. R&D on Unitized Regenerative Fuel Cell (URFC)
3. R&D on Hydrogen storage with metal hydride
4. Summary
H. Ito, Japan-Norway Energy Science Week 2015, 28 May 2015, Tokyo H. Ito, Japan-Norway Energy Science Week 2015, 28 May 2015, Tokyo 3
Grid Independent RE-Hydrogen System
Grid Connected RE-Hydrogen System Hydrogen may be used as fuel in
almost every application where fossil fuels are being used today.
Hydrogen is useful as an energy
carrier, because energy storage density is significantly high with compressed form, liquefied form, or metal hydride.
From sustainability point of view,
a synergy between hydrogen and electricity and renewable energy sources is particularly promising.
Hydrogen production with water
electrolysis must be suitable for renewable energy sources.
. F. Barbir, Solar Energy 78 (2005) pp. 661-669.
A Synergy between Hydrogen and Electricity
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Totalized Hydrogen Energy Utilization System (THEUS)
Hydrogen station
To enhance the versatility of hydrogen energy in the industrial, the commercial, and the transportation sectors through THEUS.
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Outline
URFC and MH tank have been evaluated as key components of hydrogen energy system in stationary applications.
A bench-scale URFC was installed and would be evaluated as an energy
conversion system. MH tank was developed by own and evaluated in a long time operation.
In particular, we have been focusing on the thermal energy recovery
from the both operations of URFC and MH tank.
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Overview of Unitized Reversible Fuel Cell (URFC)
URFC System
Cell reactions
Advantages Long-term and large quantities of energy
storage compared to current secondary batteries.
Continuous running permits to make a rate of operation double compared to individual use of FC and Ely.
Acquisition of oxygen as by-products
Electrolysis Overall : H2 electrode (cathode) : O2 electrode (anode) :
Fuel Cell Overall : H2 electrode (anode) : O2 electrode (cathode) :
+22H 2e H ( )g−+ → ↑
+2 2H O( ) 2H 1/ 2O ( ) 2el g −→ + ↑ +
2 2 2H O( ) H ( ) 1/ 2O ( )l g g→ +
2 2 2H ( ) 1/ 2O ( ) H O( )g g l+ =+
2H ( ) 2H 2eg −→ ++
2 21/ 2O ( ) 2H 2e H O( )g l−+ + →
URFC
Hydrogen Storage Unit
H2 H2
Pure Water
Fuel Cell (FC)
Power OutputPower Input
Heat
Water O2/Air
Electrolyzer (Ely)
Possible applications Hydrogen energy storage system for load
leveling at buildings Remote hospital Lake water purification Remote UPS system
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←DC Power
←DC Load
←Chiller
DI water supply
URFC stack
Installation of a bench-scale URFC
Overview
Inside
• Installed in March 2014 • Supplied from Takasago Thermal Engineering Co.
H. Ito, Japan-Norway Energy Science Week 2015, 28 May 2015, Tokyo H. Ito, Japan-Norway Energy Science Week 2015, 28 May 2015, Tokyo 8
Specifications of bench-scale URFC
Electrolysis operation
Input power (rated) 4.5 kW Gas production rate H2: 1.0Nm3/h, O2: 0.5Nm3/h Gas pressure H2: 0.9MPa(G)_max, O2: Atmospheric
Fuel cell operation
Power output (rated) 0.8 kW H2 utilization >90% H2 pressure <0.05MPa(G)
System
Cell/stack Membrane Nafion 115
Electrocatalyst H2 side Pt O2 side Pt/Ir-black
Active area 250 cm2
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Schematic draw of gas/liquid flows around URFC
Circulationpump
Water purifier
Membranehumidifier
Chiller
Chiller
Blower
Water drain
Air
Air / O2
DI water
Chiller
Circulationpump
Chi
ller
BH2
H2
Gas (O2)-waterseparator
Gas (H2)-waterseparator
Circulationpump
Pump-1
Pump-2
Pump-3
BLW
Component Rated power consumption
Cooling water pump (Pump-1) 90 W Water circulation pump (Pump-2) 60 W H2 circulation pump (Pump-3) 26 W Air blower (BLW) 500 W
• Hydrogen is recirculated. • Air is humidified using a membrane humidifier.
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Electrolysis operation - i-V characteristics
At 40°C
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15
16
17
18
19
0 0.2 0.4 0.6 0.8 1 1.2C
ell s
tack
vol
tage
[V]
Current density [A/cm2]
900 kPaG(60°C)
500 kPaG(60°C)
0 kPaG(60°C)
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15
16
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18
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0 0.2 0.4 0.6 0.8 1 1.2
Cel
l sta
ck v
olta
ge [V
]
Current density [A/cm2]
900 kPaG(40°C)
500 kPaG(40°C)
0 kPaG(40°C)
At 60°C
The effect of temperature on the performance was relatively large, while the effect of pressure was small.
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Fuel cell operation
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5
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7
8
9
10
0 0.1 0.2 0.3 0.4 0.5 0.6
Cel
l sta
ck v
olta
ge [
V]
Current density [A/cm2]
70 °C
60 °C
The cell/stack performance was significantly influenced by the operating temperature, which should be higher than 60 °C.
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Continuous operation
H2 pressure
Current
Voltage
Cell temp.
Fuel cell mode Electrolysis mode Switching (ca. 5min)
←0.9MPa 75℃→
100A→
7.9V→
←22V
←60℃
←250A
Switching
Current
Voltage
Cell temp.
Since the operation interface was well-organized, the system could be operated and switched easily. Switching time was 5-10 min.
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Schematic of the experimental set-up
Metal hydride bed in AIST
Experimental set-up of MH tank
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Metal Hydride Tank
(Metal hydride alloy) - Japanese version - Composition: MmNi5 Total weight: 50 kg Size:500 μm Reaction heat ∆h Absorption: 28.93 kJ/molH2 Desorption: 27.87 kJ/molH2
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Individual absorption/desorption test results
H/M=0.18-0.94 MH utilization ratio: 94% GH2: 5920 NL
Operating conditions (Absorption: 9 hour) H2 flow rate: 11.0 NL/min Circulation water : 32 ℃, 1.12 l/min (Desorption: 13 hour) H2 flow rate: 7.6 NL/min Circulation water : 12 ℃, 0.46 l/min
P-C isotherm Absorption Desorption
Qcw = 6.84 MJ, ε = 89.4 % Qcw = 6.62 MJ, ε = 89.8 %
Reaction heat recovery rate:ε = (Qcw/QMHreact)×100
∵QMHreact = VH2×∆h
Recoverd thermal energy from coolant: Qcw
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Absorption-desorption continuous test results
(a) P-C isotherm (b) Temperature of coolant
Reaction heat recovery rate, ε Day1 AB 87.4 % DS 73.3 % Day2 AB 75.4 % DS 72.5 % Day3 AB 76.2 % DS 72.3 %
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Summary
In this study, we investigated the performance of URFC and MH tank as key components of hydrogen storage system. The bench-scale URFC could operated quite successfully. The performance of each operation mode in URFC was comparable
with that of individual apparatus of PEM electrolyzer and PEMFC. MH tank was developed and tested in daily cycle operation.
Reaction heat recovery rate was excellent as over 70 %.
The connection between URFC and MH tank was completed, and
consolidated test is ongoing.
H. Ito, Japan-Norway Energy Science Week 2015, 28 May 2015, Tokyo H. Ito, Japan-Norway Energy Science Week 2015, 28 May 2015, Tokyo
Thank you very much for your attention!
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Hiroshi Ito [email protected]