Post on 19-Feb-2022
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Advancement of Solar Thermal Technologies
Jane H. DavidsonDepartment of Mechanical Engineering
University of Minnesota
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Renewable energy potential is many times the world demand for energy
NG 23%
Nuclear 8%
Petroleum 40% Coal 23%
Biomass 47%
Wind 2%
Hydroelectric 45%
Geothermal 5%
Solar <1%Renewables
6% Diffuse and intermittent
~1000 W/m2
Capture/convert/store/ transport Initial cost Rapid scale-up &
deploymentSource: Renewable Energy Trends 2004; Energy Information Administration, August 2005.Note: Total U.S. Energy Supply is 100.278 QBtu; Energy Information Administration, August 2005.
Challenges
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SOLAR ENERGY OPTIONS Utility Scale Concentrating solar
thermal power Solar fuels Photovoltaics Wind Biomass
Distributed Heating/cooling Hot water Photovoltaics
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State of the Art: Distributed Low Temperature Solar Technology
Hot water, space conditioning, agriculture, industrial process heat, ventilation air
Temperatures < 100 °C Proven and reliable for hot water
− Rated and certified by SRCC− Annual efficiency = 40%
Immediately deployable 1% market penetration for H2O
Use & Status
Conventional flat plate collector
Ventilation for space heating
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The Potential Benefitsfor US Buildings
Transportation27%
Commercial 16%
Residential 20%Industrial
37%
65% of total U.S. electricity consumption 36% of total U.S. primary energy use 30% of total U.S. greenhouse gas emissions
Buildings
Source: Energy Consumption US DOE Annual Energy Outlook
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Distributed Low-temperature Solar Thermal
Barriers Initial Cost Storage capacity for space conditioning Building integration
Current Research Focus A paradigm shift from copper and glass components to mass manufacture with polymers High strength, high thermal conductivity polymeric
materials for absorbers and heat exchangers Glazing and heat exchange materials that resist degradation due to UV radiation, water and oxygen, and mechanical and thermal stresses Fundamental research on particle-surface interaction
and precipitation/deposition process Development and characterization of compact storage
media
50 µm
CaCO3 on PPWang, Y., Davidson, J.H., and Francis, L., J. of Solar Energy Engineering, 127, 1, 3-14, 2005.
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Concentrated Solar Thermal
100 SunsLine focus; limited to 750K
1000 Suns2-axis tracking; 1000K
10,000 Sunson-axis tracking; 2500K
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State of the Art: Solar Thermal Electricity
(Concentrating Solar Power)
11 MW-e/ 55 MW-th (Sevilla, Spain) 624 heliostats; each 120 m2 Tower height: 100 m Rankine-cycle Converstion = 21% peak and 16% avg. Cost (incl. power block): 35 M€
Potentially lowest-cost utility scale solar electricity for the Southwest
4.56 GW installed or planned in US, Mexico, Europe, Middle East, Asia and Africa
Annual Performance̶ Solar to electric conversion 12 to 25%̶ Capacity factor 30 to 75%
Current Cost - 12 to 14 ¢/kWh̶ 2011 - 8 to 10 ¢/kWh̶ 2020 - 3.5 to 6 ¢/kWh
Use & Status
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Barriers and Research Needs Materials̶ Selective surfaces for external receivers in towers and
dishes̶ Optical materials that are cheaper than glass but still
provide long life operation̶ Engineered surfaces that prevent dust deposition̶ High-temperature materials for tower and dish receivers̶ Thin film protection layers for reflectors
Thermal storage for CSP Working fluids with greater operating temperature range More efficient receivers
Solar Thermal Electricity (Concentrating Solar Power)
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Evolving: Thermochemical Production of Fuels
Prototype and laboratory scale̶ Material synthesis & processing̶ Hydrogen production̶ Gasification̶ Reformation̶ Recycle of hazardous wastes
Use & Status
Solar Fuels
Absorption Heat
QH,TH
ChemicalReactor
FuelCell
W
QL,TL
ConcentratedSolar Radiation
Reactants
“The fact that sunlight reaching the earth is essentially at a temperature of 5800 K thus gives it obvious advantages as a source of process heat for the production of chemical fuels. It is up to us to exercise our ingenuity to invent a mechanism by which it can be done.”
E. A. Fletcher, Science 197, pp. 1050-1056, 1977
Upgraded fossil fuels
Converts solar radiation to chemical potential
Provides long-term storage Cost competitive if carbon emissions
are considered
DecarbonizationH2O-splitting
Solar Hydrogen
ConcentratedSolar Energy
Fossil Fuels(NG, oil, coal)
Optional CO2/C Sequestration
H2O
SolarGasification
SolarReforming
SolarThermolysis
SolarThermochemical
Cycle
Solar Electricity
+Electrolysis
Graphics courtesy of Prof. Aldo Steinfeld, ETH-Zurich
∆H°
∆G°
T∆S°
-50
0
50
100
150
200
250
300
1000 2000 3000 4000 5000
[kJ/
mol
]
Temperature [K]
H2OHOH2
OHO2
00.10.2
0.30.40.50.60.70.80.9
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2000 2500 3000 3500 4000
Temperature [K]
Equilibrium Mole Fractionp = 1 bar
2 2 2H O H + ½ O→
Solar Thermolysis
Direct thermolysis is not practical: Requires extremely high temperatures for reasonable dissociationA most critical problem is the need to separate H2 and O2 at high temperatures.
Two-Step Water Splitting Cycle
H2H2O
½ O2
HYDROLYSERZn + H2O = ZnO + H2
∆H = -62 kJ/molTL = 700 K
SOLAR REACTOR ZnO = Zn + ½ O2
∆H = 557 kJ/mol TH > 2000 K
ZnO Zn
ZnO recycle
0
0.8
1
Temperature [K]0 1000 2000 3000 4000
Carnotabsorption η⋅η
Carnot
10005,000
10,0000.2
0.4
0.620,000
1) High specific surface area augments the reaction kinetics, heat transfer, and mass transfer
2) Large surface to volume ratio favors complete or nearly complete oxidation3) Entrainment in a gas flow allows for continuous and controllable feeding of
reactants and removal of products4) Proof of concept with 95% conversion5) Next steps: to understand the kinetics of the combined formation and hydrolysis
reaction particularly the particle interactions that are concurrent with chemical reaction
Benefits
Formation of zinc nanoparticles followed by in-situ hydrolysis for hydrogen generation.
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Barriers and Research Needs Solar Step̶ Radiative transport coupled to reaction kinetics of
heterogeneous chemical systems̶ Radiative exchange with particle suspensions in a
variety of applications̶ High temperature materials and coatings
Hydrogen Production Step• Particle size resolved kinetics of hydrolysis of single
particles • Coupled Processes in particle/steam flow
Solar Thermochemical Fuels
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• Recommendations
1. Support research on a variety of solar technologies
1. For more mature technologies such as low temperature solar thermal and concentrating solar power focus on cost reduction strategies
1. Invest in basic research on solar thermochemical production of fuels
Decarbonization of fossil fuels and carbothermal reduction processesThermochemical water splitting cycles with no carbon emission
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• References– Low temperature distributed solar thermal1. Davidson, J.H., Mantell, S.C., and Jorgensen, G., “Status of the Development of Polymeric Solar Water Heating
Systems,” in Advances in Solar Energy, D.Y. Goswami, ed., American Solar Energy Society, Vol. 15, pp. 149-186, 2002.
2. Davidson, J.H., Mantell, S.C., and Francis, L.F., “Thermal and Material Characterization of Immersed Heat Exchangers for Solar Domestic Hot Water”, in Advances in Solar Energy, D.Y. Goswami, ed., American Solar Energy Society, Vol. 17, pp. 99-129, 2007.
3. Davidson, J. H., “Low-Temperature Solar Thermal Systems: An Untapped Energy Resource in the United States,” ASME J. of Solar Energy Engineering, 127, 3, 305-306, 2005.
4. Wang, Y., Davidson, J.H., and Francis, L., “Scaling in Polymer Tubes and Interpretation for Their Use in Solar Water Heating Systems,” ASME J. of Solar Energy Engineering, 127, 1, 3-14, 2005.
– Concentrating solar power1. Mancini, T., P. Heller, B. Butler, B. Osborn, S. Wolfgang, G. Vernon, R. Buck, R. Diver, C. Andraka and J., Moreno,
2003, “Dish Stirling Systems: An Overview of Development and Status,” J. Solar Energy Engineering, Vol. 125, pp, 135-151.
2. Pitz-Paal, P., J. Dersch, B. Milow, F. Tellez, A. Ferriere, U. Langnikel, A. Steinfeld, J. Karni, E. Zarza, and O. Popel, 2005, “Development Steps for Concentrating Solar Power Technologies with Maximum Impact on Cost Reduction,” Proceedings of the 2005 International Solar Energy Conference, August 6-11, Orlando, FL.
3. Sargent &Lundy Consulting Group, 2003, “Assessment of Parabolic Trough and Power Tower Solar Technology Cost and Performance Forecasts,” SL-5641, prepared for the U.S. Department of Energy and the National Renewable Energy Laboratory, Chicago, IL.
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• References– Solar thermochemical processes1. E.A. Fletcher, and R.L. Moen, 1977, “Hydrogen and Oxygen from Water, “ Science, Vol. 197, pp. 1050-1056.1. Nakamura, T., 1977, “Hydrogen Production from Water Utilizing Solar Heat at High Temperatures,” Solar Energy,
19(5), pp. 467-475.2. Steinfeld, A., Kuhn, P., Reller, A., Palumbo, R., Murry, J., Tamaura, Y., 1998, “Solar-processed metals as Clean
Energy Carriers and Water Splitters,” Int. J. Hydrogen Energy, 23, pp. 767-774.3. Fletcher, E.A. Solarthermal Processing: A review. J. of Solar Energy Engineering 2001; 123:63-74.4. Perkins, C., Weimer, A. W., 2004, “Likely Near-term Solar-thermal Water Splitting Technologies,” Int. J. Hydrogen
Energy, 29, pp. 1587-1599.5. Steinfeld, A., 2005, “Solar Thermochemical Production of Hydrogen—a Review,” Solar Energy, 78, pp.:603-615.6. Weiss, R.J., Ly, H.C., Wegner, K., Pratsinis, S.E., and Steinfeld, A., 2005, “H2 Production by Zn Hydrolysis in A
Hot-Wall Aerosol Reactor,” AIChE J., 51, pp. 1966 -1970.7. Wegner, A., K., Ly, H.C., Weiss, R.J., Pratsinis, S.E., and Steinfeld, A., 2006, “In Situ Formation and Hydrolysis of
Zn Nanoparticles for H2 Production by the 2-Step ZnO/Zn Water-Splitting Thermochemical Cycle,” Int. J. Hydrogen Energy, 31 pp. 55–61
8. Ernst, F.O., Tricoli, A., Pratsinis, S.E., and Steinfeld, A., 2006, “Co-Synthesis of H2 and ZnO by In-Situ Zn Aerosol Formation and Hydrolysis,” AIChE J., 52(9), pp. 3297-3303.
9. Harvey, W.S., Davidson, J.H., and Fletcher, E.A., “Thermolysis of Hydrogen Sulfide in the Range 1300 to 1600 K,” Industrial and Engineering Chemistry Research, 37, 6, 2323-2332. 1998.