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Green Hydrogen for the Future Sustainable
Growth of Human Beings
Kenichiro OTA
Green Hydrogen Research Center
Yokohama National University, JAPAN
CCUS and H2 International Conf.、Feb. 20th, 2020,
Belle Salle Kanda, Chiyoda, Tokyo, Japan
◆Global Warming, Carbon Cycle vs. Water Cycle
◆Green Hydrogen Energy System
◆Water Electrolysis
◆Polymer Electrolyte Fuel Cell
Green Hydrogen Research Center, Y.N.U.
4.5oC
2.0oC
1.5oC
0.0
1.0
2.0
3.0
4.0
5.0
-1.0
700 1000 1500
Year
21001900
Temp. Increase/℃
(by IPCC 4th Report(2007)
Rapid Global Warming on the Earth
Green Hydrogen Research Center, YNU
Solar energy
Low entropy
Heat radiation to the space
Disposal of produced entropy
Resources for
the human society
Human society
Global environment
Entropy production by the activity
of the mankind
Entropy production by the activity
of the global environment
Wastes from the
human society
Materials circulation
Q: 1.2x1014kW
ΔS=4.7 x 1011 kJ/K・s
The earth is a closed system.
Global entropy flow for sustainable growth
Green Hydrogen Research Center, YNUCarbon cycle on the earth
Sin
kin
g
flow
Atmposphere750 (360ppm CO2) (Annual increase 3.2)
Land
Vegetation 610
Soils and detritus 1580
Ocean surface 1020
Marine biota
3
Intermediate and
deep ocean
38100
Surface sediment
150
Cha
ng
ing la
nd-u
se1.6
0.5
Respira
tion
decom
positio
n
60
Photo
synth
esis
61.4
5.5
Em
issio
n
from
the s
ea
surfa
ce
90
Absorp
tion
to th
e s
ea
surfa
ce
92
6
Remains
Excrement
4
60.2
Upw
ellin
g
flow
100 91.6
□ : Carbon storage quantity. Gt Carbon
→ : Movement. Gt Carbon/year
Human activity
Fossil fuels
12000
Resp
iratio
n
deco
mp
ositio
n
50
Photo
-
synth
esis
40
Dissolved
organic carbon
700
Green Hydrogen Research Center, YNU
□ ; Water storage quantity. Tt water
→ ; Movement. Tt water/year
Land
Vegetation.
Snow, ice 43,400
Surface water 360
Groundwater 15,300
Marine 1,400,000
Rain
fall
110.4
Reduced water
43.8
Marine atmosphere 11Land atmosphere 4.5Vapor transport
43.8
Evapora
tion 66.6 453.4
Rain
fall
409.6
Evapora
tion
Water cycle on the earth
Green Hydrogen Research Center, YNU
Solar Energy
Low Entropy
Disposal of Entropy
To Universe
Human Society
Earth
Entropy Production by Human Activity
Natural Entropy ProductionH2O→H2+1/2O2
H2+1/2O2 → H2O
Water Circulation
H2 H2O Heat
Hydrogen Economy and Water Circulation
Green Hydrogen Research Center, YNU
carbon water
Total amount 54Tt 1,460,000Tt
Atmosphere abundance 750Gt 15.5Tt
Annual movement from atmosphere
152Gt/yr 496Tt/yr
Average retention period in atmosphere
5 yaer 10 day
27000 Times
21Times
3160 Times
Comparison between water cycle and carbon cycle
180 Times
Green Hydrogen Research Center, YNU
Earth Japan
Natural Carbon Cycle 150Gt/y 0.37Gt/y
Carbon (CO2) Emission
by Energy Consumption
5.5Gt/y 0.32Gt/y
EIF of Carbon 0.036 0.86
Environmental Impact Factor of Carbon
Carbon (CO2) Emission by Energy Consumption
/ Natural Carbon Circulation
EIF (Environmental Impact Factor) of Carbon
D.S.Shimel; Terrestrial ecosystems and the carbon cycle, global change biology(1995)
Green Hydrogen Research Center, YNUEIF of H2 Energy
= (H2O through H2 Energy System) / (Natural Water Vaporization)
Earth Japan
Annual
Vaporizaiton
5×1014t /y 2.3×1011t/y
H2O through H2
Energy System
5×1010 t/y 1.4×109t/y
EIF of H2 ~0.0001 0.006
EIF (Environmental Impact Factor of Hydrogen
Green Hydrogen Research Center, Y.N.U.
Dependence of EIF on Consumption Density (2004-2013)
Energy Consumption Density [MJ/m2]
1
10 100 1000
0.0001
0.001
0.01
0.1
10
100
Fossil Fuel
Green Hydrogen
0.036
To
kyo
Osa
ka
Kan
ag
aw
a
Aic
hi
Sa
ita
ma
Fu
ku
oka
Hyo
go
Sh
izu
oka
Ya
ma
gu
ch
i
Sa
ga
Ish
ikaw
a
Ku
ma
moto
Gifu
Ko
ch
i
Hokka
ido
En
viro
me
nta
lIm
pa
ct F
acto
r [-
]
Iba
ragi
CO2 from Energy Usage
EIF(Fossil Fuel)= ---------------------------------
CO2 of Natural Circulation
H2O from Energy Usage
EIF(H2)= ---------------------------------
H2O of Natural Circulation
Green Hydrogen Research Center, YNU
Green Hydrogen Energy System
Nuclear energy
Renewable energy
Thermal energy Power
Fossil fuel
Electric energy HydrogenFuel cell
Water electrolysis
Green Hydrogen: Hydrogen from water using renewable energy.
Green Hydrogen Research Center, YNU
Future of Primary Energy
Fossil EnergyLimited resources: ultra high efficiency for use
Nuclear EnergyAgainst earth quake and tsunami
Waste treatment
Safety science for nuclear usage
Renewable energyHydroelectric power
Photovoltaic power
Biomass energy
Geothermal energy
Wind power
Green Hydrogen Research Center, YNU
➢Storage of Electricity◆Mechanical storage ( compressed gas, fly wheel)
◆SMES
◆Capacitor
◆Battery
◆Hydrogen (or chemical)gas, liquid, metal hydride, organic hydride
◆Pumped hydro
➢Long distance transport of electricity◆ Liquid hydrogen
◆ Organic hydrogen (Toluene/MCH system)
Storage and Transport of Renewable Energies
Comparison of storage system of electric power
Storage Time
GW
MW
kW
W
sec min hour day month
Po
wer
Capacitor
Battery
SMES
Pumped Hydro
Hydrogen
Green Hydrogen Research Center, YNU
(NEDO report)
Cost of power generation in Japan
Biomass Wind
[yen/kWh]
Cost
Solar cell Small hydro Geothermal LNG Power
Cost
Cost of wind power
[yen/kWh]
Cost
Land LandOff shore Off shore
World Japan
Green Hydrogen Research Center, YNU
Hydrogen from water
・Water electrolysis : Electricity from renewable energy .
Alkaline Water Electrolysis
Polymer Electrolyte Water Electrolysis.
High Temperature Water Vapor Electrolysis.
.
・Thermochemical process : Heat (1000 oC or lower ) of HTGR, solar heat etc.
Multi-step chemical reaction
・Direct thermal decomposition : High temperature over 4000 oC.
Separation at temperature.
・Photo decomposition : Photo-chemical reaction
Complete decomposition using visible light is still impossible.
Hydrogen production method
Green Hydrogen Research Center, YNU
1.4
1.5
1.6
1.7
1.8
1.9
0 0.1 0.2 0.3 0.4 0.5
電流密度 / Acm-2
セル電圧 /
V
固体高分子型
アルカリ型
Characteristics of Water Electroysis
Alkaline Electrolyzer
Commercially available
Cheap (Fe or Ni Electrode)
Polymer Electrolyte Electrolysis
High Density, High Efficiency
Expensive (Pt or Ir base)
Cell
Voltage
Current Density
Alkaline Type
Polymer Electrolyte Type
50 ℃
Green Hydrogen Research Center, YNU
Polarization of Pt in Aqueous Solution
1M H2SO4
1M KOH
E vs. RHE / V
i/ m
A c
m2
Theoretical
Potential of HER
Theoretical
Potential of OER
-50
-25
0
25
50
0 0.5 1.0 1.5 2.0
Critical Issue of water Electrolysis
large oxygen over potential
=> Voltage loss
A New Electrode Material is needed.
Green Hydrogen Research Center, Y.N.U.
Commercial Alkaline Water Electrolyzers in 1970s
Company
Method
Pressure(kg/cm2)
Temp.(℃)
Electrolyte(KOH, %)
Current Density(A/m2)
Cell Voltage(V)
Current Efficiency(%)Power Consumption
(kWh/Nm3H2)
>99.9
4.9
Monopolar
normal
70
28
1,340
1.9
>99.9
4.9
Bipolar
normal
80
25
2,000
2.04
>98
4.9
Bipolar
normal
80
25
1,750
1.75
98.5
4.6
Bipolar
normal
80
29
1,500
1.9
98.75
4.5
Bipolar
30
90
25
2,000
1.86
Stuart Energy (Electrolyzer) ABB(BBC) Norsk Hydro De Nora IHT(Lurgi)
Target: From 5 kWh/Nm3H2 to 4 kWh/Nm3H2
Green Hydrogen Research Center, YNU
H2(g) + 1/2O2(g)
Total Energy
ΔHo
286 kJ/mol
[242 kJ/mol]
Electrical Energy
ΔGo
237 kJ/mol
[229 kJ/mol]
Heat
TΔSo
H2O(l), [H2O(g)]
Fu
el C
ell
Wate
r E
lectr
oly
sis
49 kJ/mol
[13 kJ/mol]
Energy change of water formation reaction(25oC)
Green Hydrogen Research Center, YNU
0
100
200
300
0
0.5
1
1.5
0 500 1000100
Temp./ oC
En
erg
y/k
J m
ol-
1
Total Energy (ΔH)
Vo
lta
ge
/V
Electic Energy(ΔG)
Gas
Heat(TΔS)
Liq.
H2 + 1/2O2 = H2O
Theoretical Voltage of Fuel
Cell and Water Electrolysis
Low Temp. > High Temp.
Temperature Dependence of Water Formation Reaction
Green Hydrogen Research Center, YNU
Theoretical Efficiency of Fuel Cell vs Carnot Efficiency
100
80
60
40
20
0200 500 1000 1500 2000
Effcie
ncy
/ %
Temp. / K
Carnot Eff,: C
Fuel Cell: F
εF = ΔG(T)/ΔHo(298)(HHV)
εC=(TH-TL)/TH
Fuel Cells
PEFC: Room Temp.~120℃AFC:Room Temp.~200℃PAFC:120~200℃MCFC:600~650℃SOFC:600~800℃
Green Hydrogen Research Center, YNU
Characteristics
⚫ High power density
⚫ Low operation temperature
Applications
⚫Co-generation system (CHP)
⚫ Fuel Cell Vehicle
⚫Mobile power source
Major technical issues
⚫ Cost down
⚫Improvement of performance
Polymer Electrolyte Fuel Cell (PEFC)
H2 H+
O2
H2O
O2 gasH2 gas
O2+H2OH2
e-
e-
cathode
anode
polymer electrolyte 23
Green Hydrogen Research Center, YNU
(2005.7.09 - )
1 kW home cogeneration system
The commercialization started in 2009.
Over 300,000 units are operating in Japan.
Capacity
1 kW – 700 W
Hot water (60oC, 200 L)
Daily Start and Stop
without N2 purge
(Hot water oriented mode)
Life > 10 years
The cost target: 7,000 US$/unit in 2020.
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
2005/8/25 0
:00
2005/8/25 2
:00
2005/8/25 4
:00
2005/8/25 6
:00
2005/8/25 8
:00
2005/8/25 1
0:0
0
2005/8/25 1
2:0
0
2005/8/25 1
4:0
0
2005/8/25 1
6:0
0
2005/8/25 1
8:0
0
2005/8/25 2
0:0
0
2005/8/25 2
2:0
0
Month CO2
Reduction
kg-CO2
CO2
Reduction
%
Jan 17.5 11.5
Feb 38.3 21.6
Mar 41.8 21.9
1 kW PEFC at my home
24
Green Hydrogen Research Center, YNUFCVs in Japan
Compressed H2 gas ( 70 MPa)Driving Range > 650 kmLife > 10 years (5000 h)Cold start at - 30oCOutput Power: 3 – 3.5 kW/L
NEDO’s new target is 9 kW/L
in 2040.
Commercialization has started in 2014. Target 200,000 FCVs with 320 H2 Stations in 2025.
Green Hydrogen Research Center, YNU
0 10 20 30 40 50 60 7015
25
20
E/V
H2-O2
25% H2SO4
39 st acks ( 100cm2x39)44. 2℃
30
I /A
1st Hydrogen Fuel Cell Vehicle in Japan (1988)
1.1 kW, H2/O2-100cm2x39 cells
Sulfuric Acid Type
Speed: 30 km/h
S. Motoo, R. Hirasawa, K. Ota, R. Furuya (Yamanashi Univ., Univ. of Tokyo, Yokohama Nat. Univ.) 26
Green Hydrogen Research Center, YNUProblems of Pt catalyst
965 million (in the world)
Instability of Pt cathode
Resources of PtHigh cost and limited ! !
100 kW FCV
→50 g Pt !!
39000 ton(2006)
800 million
Number of motor vehicles (2009)
Pt resources
Limit of reduction for Pt usage!
Problems of cathode catalyst
27
Green Hydrogen Research Center, YNUConcept of Non Pt Cathode for PEFCs
High stability
High catalytic
activityCombined
Group 4 and 5 metal oxides are stable in acid and O2 .
Development of innovative materials.
28
Green Hydrogen Research Center, YNU
By Toppan Printing
Operation condition
Temp. : 80℃R. H. : 100
Membrane : Nafion211
H2/O2 = 0.2/0.3 MPa-G
Loading : 10 mg/cm2
Current density / A cm-2
Cell
voltage
/ V
Zr oxide-based cathode
0.4
0.5
0.6
0.7
0.8
0.9
1.0
0 0.5 1.0 1.5
IR corrected
Single cell performance
1.2 A cm-2 @ 0.6 V (IR corrected)
2008 2010 2012 2014 201610-3
10-2
10-1
100
101
Year
TiZrTa
@ 0.6 V
H2/O2 = 0.2/0.3 MPa-G
Cu
rre
ntdensity @
0.6
V / A
cm
-2
IR included
Cell performance increased drastically.
29
Green Hydrogen Research Center, YNU
30
PEFC for Future Generation
➢More Stable Fuel Cell
➢More Efficient Fuel Cell
Operating voltage: ~ 0.9 V
Energy Efficiency: ~ 60 %(HHV)
Operating temperature : 120 oC or higher
Our target: NPGM Catalyst without Carbon.
Green Hydrogen Research Center, YNU
Zr-CNO /
MWCNT_30oC
TixNbyOz+
Ti4O7_30oC
Fig. Potential-ORR current curves of
TixNbyOz+Ti4O7 and Zr-CNO/MWCNT.
-1.2
-1.0
-0.8
-0.6
-0.4
-0.2
0
0.2
0.6 0.8 1.0 1.2
E vs. RHE / V
i OR
R/ m
A g
-1
TixNbyOz+
Ti4O7_80oC
Onset potential=1.15 V
High onset potential
High quality of active point.
More than Pt ?
Onset potential of oxide cathode
31
Green Hydrogen Research Center, YNU
1.0
1.1
1.2
Cycle /-
Eo
nse
t/
V v
s.
RH
E
80 oC
30 oC
1.2
Start-stop
cycle test
0 10000 200005000 15000
80 oC
30 oC
1.0
1.1
Load cycle
test
Onset Potential during the potential Cycle
Fig. Onset potentials of TixNbxOz supported by Ti4O7.
Eonset ~ - 20 nA/cm2, Ti:Nb = 85:15
No change during cycles.
Active points are stable.
32
Green Hydrogen Research Center, YNUAcknowledgment
The author thanks to the members of NPGM oxide cathode
project for their help and the New Energy and Industrial
Technology Development Organization (NEDO) of Japan for
the financial support.
33
Green Hydrogen Research Center, YNU
Green Hydrogen -
Key For the Future Sustainable Growth
Thank you for your kind attention!!34