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Carbon Dioxide Zero-Emission Hydrogen System based on Nuclear Power
Yukitaka KatoResearch Laboratory for Nuclear ReactorsTokyo Institute of Technology
Paper #51, 2B2 Innovative Energy TransmutationCOE-INES International Symposium, INES-11 November, 2004, Tokyo, Japan
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Contents
Back ground: Hydrogen supply for fuel cell vehiclesCO2 zero-emission hydrogen career system using a regenerative reformerExperimental demonstrationEvaluation of the hydrogen career system
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Hydrogen for FC-A fuel cell is environmental friendly?-
H2Hydrogen
source
1st Energyinput
Problems of H2 supply to a conventional fuel cell vehicleCompressed H2 fuel : high-energy consumptions for production and pressurization, and explosiveness
2nd Energyinput
Explosiveness of H2
H2 cylinder Fuel cell
H2OCompressed
H2
Fig. Subjects for hydrogen supply to a fuel cell vehicle
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Fuel reforming for hydrogen supply to a fuel cell vehicle
Problems of H2 supply to a conventional fuel cell vehicleFuel Reforming: complex structure, and CO2 emission
Fig. Conventional reforming system for a FC vehicle
CO2, H2
Cat.CH4H2O Reformer Shift
Converter
Cat.Fuel cell
CO2, H2O
Heat input Heat output
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Regenerative Reforming-Use of chemical absorption-
Fuel reforming for methaneCH4+H2O ↔3H2 +CO, ∆H°1=+205.6 kJ/mol
CO+H2O ↔H2 +CO2, ∆H°2=−41.1kJ/mol
CaO carbonationCaO(s)+CO2(g)↔CaCO3(s),
∆H°3= −178.3 kJ/mol
Regenerative reforming(CO2 absorption reforming, self-heating)
CaO(s)+CH4(g)+2H2O(g)↔4H2(g)+CaCO3(s),∆H°4=−13.3 kJ/mol
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Non-equilibrium reaction for hydrogen production
Based on fuel reformingSeparation processes for non-equilibrium reforming
Separating CO2 from system using chemical absorptionMerit of non-equilibrium reforming
Enhancement of hydrogen productionUse of exothermic reaction heat for endothermic reformingDrop in reforming temperature
CH4 steam reforming: 700oC -> 500oCEnhancement of high-carbon numbers reactant reforming
Kerosene, C2H5OH and higher hydrocarbonReuse of carbon dioxide
CO2 zero-emission system
Link with nuclear power system
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CO2 zero-emission FC vehicle using the regenerative reformer
Regenerative reformingCO2 recoverable, self heating, and simple reforming systemthermally regenerative
CO2 zero-emission FC vehicleSafety H2 carrier system
under low-pressure and high-density
CaCO3, Cat. CO2
(2) CaO regeneration/CO2 recovery
CO2 recycleprocess
Surplus heat/electricity for thermal decarbonation
CaO, Cat.CH4H2O
H2
(1) CO2 absorption reforming
Fuel cellH2O
CO2 absorption reforming
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CO2 zero-emission hydrogen career system
CO2 Hydrogenation
Regeneration Station
CaO regenerator
CO2storage
•Electricity from nuclear power plants•Heat from high-temperature gas reactor(HTGR) and H. T. industries
Recycle
Fuel cell vehicles
CH4
Electrolysis of water H2
Hydrogen system driven by surplus electricity and heat from nuclear power plants, and unstable energy.Safe and compact hydrogen transportationCO2 zero emission energy system
CH4regenerator
Renewable energy system
Electricity/ Heat HTGR
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Experiment of the regenerative reformer
Demonstration of the possibility of the regenerative reforming systemFor polymer electrolyte fuel cell (PEFC) operated at a hydrogen pressure of less 0.3 MPa.
CH4
Ar
CO2
H2
(1)
(2)
(3)
(4)
(5) (6) (7)
(8)(9)
(10)
(11)
(12)
A quartz tube, 15 mm in inner diameter and an effective heating zone length of 600 mm.
(1) flow meter, (2) evaporator, (3) micro-feeder, (4) water reservoir, (5) electric furnace, (6) reactor tube, (7) reactor bed, (8) thermocouple, (9) furnace heating controller, (10) liquid-gas separator, (11) gas chromatograph, (12) soap flow meter
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CO2 absorption reforming
0
20
40
60
80
100
0 20 40 60 80 100 120 140
c [m
ol%
]
t [min]
CH4
H2
CO
CO2
Equilibrium H2 concentration of the conventional reforming
Equilibrium H2 concentration of the regenerativereforming
T=550oC
During the initial 60 min, hydrogen production was higher than the equilibrium concentration of conventional reforming. Charged CaO absorbed well CO2by carbonation. CO2 <1%CO was removed, <1%Low-temperature reforming (conventional reform. temp. > 700oC)
Al2O3 Ni cat+CaO Fig. Temporal change of effluent composition of the regenerative reformer at 550°C
(a) regenerative reformer (RGR)
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CO2 removal from reforming gas
0
5
10
15
20
500 550 600 650 700 750 800
c CO
2 [m
ol%
]
T [oC]
MeasuredEquilibrium
RGRSQRCVR
Effluent CO2 concentration from RGR at 550°C was less than 1%.
Fig. Effect of bed temperature on effluent carbon dioxide concentration of the reformer comparing with other type reformers.
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H2 productivity
65
70
75
80
85
90
95
100
500 550 600 650 700 750 800
c H2 [m
ol%
]
T [oC]
MeasuredEquilibrium
RGRSQRCVR
94% of H2production was measured by the RGR at 550°C.
Effect of bed temperature on hydrogen production concentration of the reformers.
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Estimation ofa zero emission vehicle1 kg of H2 in order to drive for 100 km7.46 kg (9.04 liters) of CaO was required for the RGR.
Viehcle mileage km 100Hydrogen requirement kg 1.0Hydrogen production conc mol% 94CaO requirement mass kg 7.94CaO requirement volume liter 9.62
Recovered CO2 kg 5.5
SSR-FC Vehic le
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Comparison between H2 systemsTable: Scale of energy storage facilities for 100 km mileage, 14.7 kWh, 500 mol-H2 (= Petroleum of 4 L, 2.8 kg)
7.9 L9.6 kg
400 kg100 kg
67 kg
25.6 L
0 50 100 150 200
volume [liter], mass [kg]
Regenerative reformer
Advanced lead-acid battery
Advanced Li-ion battery
Matal hydride, 1.5 wt%
Hydrogen cylinder, 70 Mpa mass [kg] volume [liter]
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Estimation of the zero-emission hydrogen career system
Power plantPower plant output GW 1Night time operation durationh 8Total Electricity amount GWh 8
GW 2.88E+04FC VehicleViehcle mileage km 100Hydrogen requirement kg 1Hydrogen production conc mol% 94CaO requirement mass kg 7.94CaO requirement volume liter 9.62CO2 kg 5.5CO2 mol 125dH for regeneration kJ/mol-CO2 178
Regeneration stationRequirement reaction heat kJ/piece 2.23E+04Cell piece pieces 1.29E+06CO2 amount kg 7.12E+06
m3(STP) 3.62E+06
Nighttime surplus electricity of 1 GW for 8 hours was used for the regeneration at the regeneration stations.The RGR packages of 1.3 million pieces/dayare able to be regenerated in the stations. CO2 of 7.1×103
ton/day is expected to be recovered from the stations.
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ConclusionsThe regenerative reformer was applicable to a practical CO2 zero-emission reforming with safety hydrogen supply.The required amount of CaO for the reformer was expected to be small enough comparing with other hydrogen storage system or batteries.The system can utilize surplus electricity generated from renewable energy system and nuclear power plant.Electricity of 1 GW for 8 h can regenerate 1.3 million of reforming packages, and recover 7.1 ton of CO2.The hydrogen career system using the regenerative reformer would widen need of those power plants because the system realizes new vehicle system of total CO2 zero-emission.The hydrogen career system also contributes to load leveling of power plant operation.
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Shifting into non-equilibrium by separation
Reforming+H2 separation
Nom-equilibrium
Reforming processes
Nom-equilibrium
(a) Conventional, non-treatment
(b) H2 separation
(c) CO2 separation
CnHmOk+bH2O hydrogen
source
H2, CO2, CO, others
Equilibrium mixture
Pure H2
Pure H2
Exhaust CO2
CO2 fixation
Fuel cell
Reforming+CO2 separation
Reforming
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Unstable Operation-Load leveling for Economical Plant Operation-
Load change and unstable operation
Low-annual operation rateUneconomic
Load leveling for 100% operation
Energy storageEnergy conversion
Unstable &UneconomicalRegion
Fig. A daily load change in a summer day in JapanTokyo Electric Power Co. http://www.tepco.co.jp/
Peak Electric Load (2001)Japan=181 GWTokyo area=64 GW (24 Jul.), 51 GW (15 Jan.)
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Diversification of energy supply and demand
DemandSupply
Stable StablePresent
Future Storage
Daily and Seasonal change
Instable
Fig. Forecast of the change of energy flow pattern
Decentralization/ Renewable energy
Diversified
Future society needs high-efficient tech. of,Energy storageEnergy transportationEnergy conversion
Use of chemicalreaction
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0
5
10
15
20
25
0
20
40
60
80
100
0 50 100 150 200 250
c i [m
ol%
]
c H2
[mol
%]
t [min]
CO
CO2
CH4
H2
Pre-breakthrough Post-breakthrough
T=550oCfCH4=106Nml/min
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0
20
40
60
80
100
500o C
pre
550o C
pre
600o C
pre
500o C
pos
t
550o C
pos
t
600o C
pos
t
COCH4
CO2
H2
c [m
ol%
]
fCH4=106Nml/min
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