Development of Solar-powered Thermochemical Production …Overview Timeline • 6-25-2003 •...
Transcript of Development of Solar-powered Thermochemical Production …Overview Timeline • 6-25-2003 •...
Development of Solar-powered Thermochemical Production of
Hydrogen from Water Al Weimer for the Solar Thermochemical
Hydrogen (STCH) Team17 May 2006
This presentation does not contain any proprietary or confidential information
Project ID No. PD10
OverviewTimeline• 6-25-2003• 12-31-2005• 40%
BarriersAU. High-Temperature ThermochemicalTechnologyAV. High-Temperature Robust MaterialsAW. Concentrated Solar Energy Capital CostAX. Coupling Concentrated Solar Energy and Thermochemical cyclesBudget
•Total Project Funding
$5,614,049 DOE
$752,900 Cost share
•Funds received in FY04
$2,943,232
PartnersThe University of Nevada, Las Vegas The University of Colorado The University of Hawaii
Sandia National Laboratories The National Renewable Energy Laboratory Argonne National
Laboratory General Atomics Arizona Public Service General Electric General Motors
ETH-Zurich MVSystems, Inc. Intematix, Inc.
Objectives
• Identify a cost competitive solar-powered water splitting process for hydrogen production
• Continue experimental cycle studies needed for final quantitative selection
• Numerical and experimental evaluation of solid particle receiver performance
• Optimize heliostat/tower/secondary concentrator characteristics and configurations for various operating temperatures
Approach
• Design and implement a quantitative comparative assessment methodology to screen all known thermochemical cycles and select the top several performers
• Perform literature surveys and laboratory experiments to acquire essential evaluation and design data for the top several concepts
• Develop validated designs for collector system components for integrated system analysis
• Analyze cost and efficiency metrics for integrated cycle performance
• Develop demonstration plant concept design(s) for surviving competitive cycle(s) and provide recommended path forward
Technical Accomplishments/ Progress/Results
• Cycle database and scoring are completed• Experimental work (kinetics, thermodynamics,
and product characterization) underway for five cycles
• Some system designs optimized for various operating temperatures and power requirements
• CFD modeling and simulation carried out to develop understanding of thermal transport in reactors and solid particle receivers
Discovery and assessment of known thermochemical cycles is completed• 353 unique cycles have been discovered and scored• 12 cycles found to be worthy of further experimental study• 5 of those 12 are currently under active study by SHGR
Other•Hybrid copper chloride
Volatile Metal Oxides•Zinc oxide•Hybrid Cadmium•Cadmium Carbonate Metal Sulfates
•Cadmium sulfate•Barium-Molybdenum sulfate•Manganese sulfate
Non-volatile Metal Oxides•Iron oxide•Sodium manganese•Nickel manganese ferrite•Zinc manganese ferrite•Cobalt ferrite
Sulfuric Acid (NHI)•Hybrid sulfur•Sulfur iodine•Multivalent sulfur
Metal Sulfate Cycles were Eliminated from Consideration
“Sulfate cycles”: MO + SO2 + H2O = MSO4 + H2No experimental evidence reported.
Thermodynamically, this reaction is favorable, but side reactions are more favorable.
SHGR studied sulfate cycles with MO = MnO, BaO under a variety of conditions:
25-100oC, makes MSO3 , No H2MO + SO2 = MSO3 for M = Mn, Ba
200-260oC, 100 atm, MnSO3 , No H2MnO + SO2 = MnSO3
230-240oC, 100 atm, BaSO4 + S, No H22 BaO + 3 SO2 = 2 BaSO4 + S
MnSO3*3H2O 7-20-05, 100 C, w500
0
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10 15 20 25 30 35 40 45 50 55 60 65 70
2theta (deg)
MnSO3*3H2O powder 33-907 ref MnSO3*3H2O
We doubt that any “sulfate cycle” is feasible
X-ray diffraction shows MnSO3*3H2O
BaO + SO2 + H2O 230 C, 1440psi burst 9-22-05
0
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450
10 15 20 25 30 35 40 45 50 55 60 65 70
2theta (degrees)
powder recovered BaSO4 24-1035
X-ray diffraction shows BaSO4
Two step ZnO/Zn Process to split water
Concentrated Solar Energy
H2 (product)
Metal Oxide Decomposition
Water Splitting
O2 (vent)
Zn (solid)(stored)
ZnO (solid)
H2O (vapor)
ZnO Zn + 1/2O2
Zn + H2O ZnO + H2
∆H = 557 kJ/mol@2300 K
∆H = -62 kJ/mol@700 K
Solar Reactor
24/7
(both steps demonstrated)
Aerosol ZnO Dissociation of ZnO
•Demonstration of rapid (< 1s) ZnO dissociation for Zn/ZnO cycle•Highest conversion ever (>40%) for thermal dissociation of ZnO•Conversion consistent with kinetic model
-50
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Time (s)
Con
cent
ratio
n (p
pm)
OxygenCarbon MonoxideCarbon Dioxide
Feeding stoppedFeeding initiated
(ZnO Zn + 1/2O2; 1600 oC; Al2O3 tube)
9 cm ID x 46 cm longLab Transport Tube
Kinetic Models for Zn/ZnO CycleThermogravimetric Analysis performed to determine kinetic expression
( )23
0 1aE
RTd k edtα α
−⎛ ⎞⎜ ⎟⎝ ⎠= −
k0= 9.30 x 106 ± 0.3 x 106 s-1
Ea= 357.8 ± 12 kJ/mol
L’vov Theory:
160 102.9
/362
1−
∆
×==
=∆
=
− seFaBk
molkJHE
RS
Ta
Tν
ν
γν
o
o
-10.5
-10
-9.5
-9
-8.5
-8
-7.5
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-6.5
-60.00049 0.0005 0.00051 0.00052 0.00053 0.00054 0.00055 0.00056 0.00057 0.00058 0.00059
1/T (K^-1)
Arrhenius analysis yielded excellent agreement with prevailing kinetic theory
Hydrogen Production from Zn(Zn + H2O ZnO + H2)
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0 50 100 150 200 250 300time [min]
conc
entra
tion
[ppm
]
Zinc Feed
Water
Hydrogen
2000 ppmcalibration
360 oC 400 oC
Zn (mp)=419oC
Cadmium Carbonate Cycle might be highly efficient• Flowsheet calculations predict a steady state efficiency of
57.5%(LHV)/68%(HHV)
• High temperature reactions expected to be fast• Experimental program undertaken to investigate
hydrogen production step• High temperature studies required, especially quench
Cd + CO2(g) + H2O = CdCO3 + H2(g) 120oCCdCO3 = CdO + CO2(g) 350oCCdO = Cd(g) + 1/2 O2(g) 1450oC
Hydrogen Generated with Ammonia “Catalyst” • No hydrogen detected without a catalyst• Ammonia, supplied as NH4HCO3, promotes hydrogen
generation– Mechanism probably involves a Cd(NH3)n
+2 complex– Gas phase products determined by mass spectrometry– Final solid product is CdCO3
• Kinetics being studied– No significant change in hydrogen
generation rate between 80 and 140oC for large particle Cd
– Small particle studies underway
Sodium Manganese Cycle(500 mtorr TGA run @ 1310 oC)
-25.0
-20.0
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Time (min)
% D
elta
Mas
s
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Tem
pera
ture
(C)
3Mn2O3 --> 2Mn3O4+1/2O2
2Mn3O4 --> 6MnO+O2
Product Identifiedas MnO
Co-Ferrite lattice structure after 31 cycles
Test data showing repeatable hydrogen production over 31 cycles
Cast Part#2 - Disc Configuraton 75% PorosityYSZ:Co.67Fe2.33 O4 (3:1) Sintered at 1400C
Hydrogen Generation After 1st, 20th & 31st Cycle
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Time (min)
H 2(V
ol%
)
Part#2, Cycle 20, 1248C, 3.3cc H2
Part#2, Cycle 31, 1250, 3.41cc H2
Part#2, Cycle 1, 1325C, 2.67cc H2
Current Ferrite Activities
•Evaluate reaction kinetics with on-sun testing
•Optimize reactive material composition
•Perform additional durability testing and characterization
Cast YSZ: Cobalt-Ferrite Lattice DemonstratesRepeatable Hydrogen Production
O2
H2O H2O
O2
x
yx
y
z
Reactive material
Insulation
Concentrated solar flux
Window
Sandia -Invented device uses recuperation of sensible heat to efficiently produce hydrogen in a two -step TC process
H2, H2O
Set of counterrotating rings
Counter Rotating Ring Receiver Reactor Recuperator(CR5) Thermochemical Engine
Hybrid Copper Chloride Progress
Proof of principle demonstrated for all steps in the reaction:
2Cu + 2HCl(g) H2(g) + 2CuCl (425oC)4CuCl 2Cu + 2CuCl2 (electrochemical)2CuCl2 + H2O(g) Cu2OCl2 + 2HCl(g) (325oC)Cu2OCl2 2CuCl + 1/2O2(g) (550oC)
Low temperature Cu-Cl cycle showed promising efficiency(~40% LHV),but some critical data must be determinedexperimentally
• Baseline System– 200m Tower– 100m2 heliostats
• 358 per field• 3 elliptical fields/tower• 3 focal lengths/field• ρ = 0.92• σslope = 1.3 mrad
– CPC Secondary• 23.5o acceptance angle• Cgeometric = 6.1
– Design, size and performance of secondary can be improved with further optimization
Ultra-High Temperature Advanced Tower ConceptMultiple Field & Secondary/Tower, Single Reactor/Tower
Annual Solar Performance
• Yearly Direct Daggett: 2787 kWhr/m2 (2679 kWhr/m2 available)• Yearly Delivered: 1990 kWhr/m2
• Annual Energy Delivered (to drive process): 259 MWhr/tower• Economies of scale for reactor/process components and infrastructure
provide significant cost advantage to advanced tower over dish systems for large scale plants
Based on Daggett TMY Solar Data
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1200 1400 1600 1800 2000 2200 2400
Receiver Temperature, oC
Effic
ienc
y To
Pro
cess
Dish, C=7000
Dish, C=4000
Central Receiver
Baseline
Preliminary Solar Receiver ConceptT (K)
8000 W (3000 suns)Tmax = 2341 KTave = 2107 KX = 60.3%ZnO: 80 g/min
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Pathlength (m)
Tem
pera
ture
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Particle temperature along the tube with higher temperatures closer to the tube wall
ZnO: 2 g/min
(to be tested)
Solid Particle Advanced Solar Receiver for Thermochemical Processes
Lift
Receiver
Hot Tank
Cold Tank
HeatExchanger
Particle curtain
Aperture
•The solid particle receiver can achieve temperatures in excess of 950 oC
•Falling ceramic particles are directly heated by concentrated solar energy
•The complete solar interface includes two-tank storage and particle lift as well as a heat exchanger to couple the receiver to the thermochemicalprocess -Completed first level component design
-Began cold flow testing
CFD Analysis - Solid Particle Solar Receiver
• Operating condition for high outlet particle temperature (sulfur-iodine thermochemicalprocess, Particle temperature >1200 K)
• Decreasing the mass flow rate• Enlarging the particle size• Increasing the solar irradiation flux
air flow path lines
Particle track
Cavity efficiency as a function of particle size and particle mass flow rate. Solar irradiation flux : 920 kw/m2
Parabolic mirrorsInner reaction tube
Modified SiC insulating tube
Alumina insulation
Windowless Tubular Receiver
High Flux Solar Simulator
ETH-Zurich Solar Simulator
Future Work
• Experimentally resolve the uncertainties of the down selected cycles; close cycles
• Optimize system design for various temperatures and power requirements
• Develop and validate the transport mechanisms and the design of the solid particle receiver
• Update H2A process economics• Investigate materials challenges for solar receiver
and other system components