basic principles of solar radiation and ste plants
TRANSCRIPT
Almería (Spain), June 27-28 , 2012“3rd SFERA Summer School” 1
Eduardo ZarzaCIEMAT-Plataforma Solar de Almería,
Apartado 22, Tabernas, E-04200 AlmeríaPhone: 950387931 E-mail: [email protected]
Basic principles of solar radiation and STE plants
3rd SFERA Summer School
Almería (Spain), June 27-28 , 2012“3rd SFERA Summer School” 2
Solar Concentrating Systems
Solar Thermal Electricity (STE) Plants
The Sun and the solar radiation
Índice de la Presentación
STE technologies comparison
Basic principles of Solar Radiation and STE Plants
Almería (Spain), June 27-28 , 2012“3rd SFERA Summer School” 3
Solar Concentrating Systems
Solar Thermal Electricity (STE) Plants
The Sun and the solar radiation
Índice de la Presentación
STE technologies comparison
Basic principles of Solar Radiation and STE Plants
Almería (Spain), June 27-28 , 2012“3rd SFERA Summer School” 4
The Sun and the Solar radiation
Sun is a huge nuclear reactor (7x105
km radius)
emitting a great amount of radiant energy (3,8x1023
kW, 5800ºK), which can be easily converted into thermal energy
Almería (Spain), June 27-28 , 2012“3rd SFERA Summer School” 5
Spectral Solar Irradiance
0,0 0,5 1,0 1,5 2,0 2,50
250
500
750
1000
1250
1500
1750
2000
2250
Extraterrestrial solar radiation
Wave length (μm)
Spe
ctra
l sol
ar ir
radi
ance
(W/m
2 ·μm
)
Solar radiation at ground level(Air Mass = 1.5)
LE
L
L/LE = 1.5
Almería (Spain), June 27-28 , 2012“3rd SFERA Summer School” 6
The Sun and the Solar radiation
The Earth intercepts only 1,7x1014
kW of solar radiation (10 days ≅
known fossil fuels resources)
The solar irradiance outside the atmosphere is almost constant (its value is called “Solar Constant”, 1367 W/m2)
Solar radiation at ground level has two components: Direct Radiation and Difuse Radiation.
Sun is a huge nuclear reactor (7x105
km radius)
emitting a great amount of radiant energy (3,8x1023
kW, 5800ºK), which can be easily converted into thermal energy
Almería (Spain), June 27-28 , 2012“3rd SFERA Summer School” 7
Direct and Difuse Solar RadiationDi
rect
Radia
tion
Dire
ctRa
diatio
n
Dire
ctRa
diatio
n Diffuse Radiation
Diffuse RadiationDiffuse Radiation
b) d ≈ λ/4 c) d > λa) d < λ/10
Almería (Spain), June 27-28 , 2012“3rd SFERA Summer School” 8
The Sun and the Solar radiation
The Earth intercepts only 1,7x1014
kW of solar radiation (10 days ≅
known fossil fuels resources)
The solar irradiance outside the atmosphere is almost constant (its value is called “Solar Constant”, 1367 W/m2)
Solar radiation at ground level has two components: Direct Radiation and Difuse Radiation.
Only Direct Solar Radiation can be concentrated.
Solar radiation reaching any point is not composed of a single ray, but of a cone of rays within a solid angle of 32”
(approx.).
Sun is a huge nuclear reactor (7x105
km radius)
emitting a great amount of radiant energy (3,8x1023
kW, 5800ºK), which can be easily converted into thermal energy
Almería (Spain), June 27-28 , 2012“3rd SFERA Summer School” 9
The Sun and the Solar radiation
α
= inicidence angle β
= Reflection angle
α
= β
Reflecting surface
32”
Almería (Spain), June 27-28 , 2012“3rd SFERA Summer School” 10
Solar Concentrating Systems
Centrales Termosolares y Crecimiento Sostenible
The Sun and the solar radiation
Situación actual
Conclusiones
Índice de la Presentación
Introducción a los SistemasSolaresTérmicos deConcentración
Almería (Spain), June 27-28 , 2012“3rd SFERA Summer School” 11
Solar Radiation and its ConcentrationSolar Concentration: Why?
Since solar radiation suffers a significant attenuation in its way to the Earth (from 63,2 MW/m2 to 1 kW/m2) we have to concentrate solar radiation in order to compensate for its low flux density at the Earth surface and thus achieve higher temperatures and efficiencies.
Almería (Spain), June 27-28 , 2012“3rd SFERA Summer School” 12
Dependence of the Efficiency and the Optimum Working Temperature on the Solar Radiation Concentration Factor
η = f(C, T)
Efficiency versus concentration factor
0
0.25
0.5
0.75
1
0 1000 2000 3000 4000
Temperatura (K)
1.000
5.000
10.000
20.000
Carnot
C=250
0
0.25
0.5
0.75
1
0 1000 2000 3000 4000
Temperature (K)
Syst
em E
ffici
ency
1.000
5.000
10.000
20.000
Carnot
C=250
Almería (Spain), June 27-28 , 2012“3rd SFERA Summer School” 13
Solar Radiation and its Concentration
Solar Concentration: Why?Since solar radiation suffers a significant attenuation in its way to the Earth (from 63,2 MW/m2 to 1 kW/m2) we have to concentrate solar radiation in order to compensate for its low flux density at the Earth surface and thus achieve higher temperatures and efficiencies.
Ways to concentrate the direct solar radiationa) by Reflection
b) by Refraction
Almería (Spain), June 27-28 , 2012“3rd SFERA Summer School” 14
Direct radiation
Reflecting surface
Receiver
Direct radiation
a) by Reflection
Direct Solar Radiation can be concentrated by Reflection and by Refraction:
Receiver
Direct radiation
b) by Refraction
Fresnel lens
Solar Radiation and its Concentration
Almería (Spain), June 27-28 , 2012“3rd SFERA Summer School” 15
Solar Radiation and its Concentration
Limiting factors for solar concentration
Theoretical and practical limits for solar concentration• Point focus concentrators: 46200 (theoretical); 5000 y 10000 (practical)• Linear focus concentrators: 220, (theoretical); 20 –
80 (practical)
a) The apparent size of solar sphere is 32´as seen from the Earthb) Inaccuracies and optical errors of solar concentrators
Solar Concentration: Why?Since solar radiation suffers a significant attenuation in its way to the Earth (from 63,2 MW/m2 to 1 kW/m2) we have to concentrate solar radiation in order to compensate for its low flux density at the Earth surface and thus achieve higher temperatures and efficiencies.
Ways to concentrate the direct solar radiationa) by Reflection
b) by Refraction
Almería (Spain), June 27-28 , 2012“3rd SFERA Summer School” 16
32”
Actual shape
Theoretical shape
Concentration limit due to the Sun disk size
Concentration
= L/π·dd
L
Almería (Spain), June 27-28 , 2012“3rd SFERA Summer School” 17
Solar Concentrating Systems
Solar Thermal Electricity Plants
The Sun and the solar radiation
Situación actual
Conclusiones
Índice de la Presentación
Introducción a los SistemasSolaresTérmicos deConcentración
Almería (Spain), June 27-28 , 2012“3rd SFERA Summer School” 18
Solar Thermal Electricity PlantsWhat is a Solar Thermal Electricity (STE) plant ?A STE plant is a system where
solar radiation is concentrated and then converted intothermal energy at medium/high temperature (300ºC –
800ºC). This thermal energy is then used in a thermodynamic cycle to produce electricity.
Almería (Spain), June 27-28 , 2012“3rd SFERA Summer School” 19
Optical Concentrator
RECEIVER
Waste Heat
Heat
Thermallosses
Opticallosses
Simplified Scheme of a typical STE PlantSimplified Scheme of a typical STE PlantDirect Solar Radiation
ConcentratedSolar Radiation
ThermalStorage
Solar System
Mechanical energy
G Electricity generator
ThermodynamicCycle
Almería (Spain), June 27-28 , 2012“3rd SFERA Summer School” 20
What is a Solar Thermal Electricity (STE) plant ?
There is a huge market worldwide for these solar plants
These plants do not increase the emissions of CO2 :
-
Every GWh
of electricity produced by a STP plant saves 800 tons of CO2
There are many Countries with good solar radiation level
-
A STP plant saves 2000 Tons of CO2
per year and MWe
installed
Why are Solar Thermal Power plants interesting nowadays ?
These plants demand a lot of manpower for construction, as well as for O&M
It is already profitable in some Countries due to public subsidies or incentives
The technology is mature enough for commercial deployment
A STE plant is a system where
solar radiation is concentrated and then converted intothermal energy at medium/high temperature (300ºC –
800ºC). This thermal energy is then used in a thermodynamic cycle to produce electricity.
Solar Thermal Electricity Plants
Almería (Spain), June 27-28 , 2012“3rd SFERA Summer School” 21
100 mHeliostat field
Receiver
Power Conversion System
Tower
Current Technologies for STE plants (I)Central Receiver Technology
Almería (Spain), June 27-28 , 2012“3rd SFERA Summer School” 22
Receiver Tube
Parabolic trough concentratorStructure
Current Technologies for STE plants (II)Parabolic Trough Collectors
Almería (Spain), June 27-28 , 2012“3rd SFERA Summer School” 23
Solar field
Power Conversion System
STE Plant with Parabolic Trough Collectors
Current Technologies for STE plants (II)
Almería (Spain), June 27-28 , 2012“3rd SFERA Summer School” 24
ConcentratorReceiver
Structure
Stirling DishesCurrent Technologies for STE plants (III)
Solar Stirling engine
Almería (Spain), June 27-28 , 2012“3rd SFERA Summer School” 25
Receiver pipe
Rectangular reflectors
Linear Fresnel ConcentratorCurrent Technologies for STE plants (and IV)
Almería (Spain), June 27-28 , 2012“3rd SFERA Summer School” 26
Technologies comparison
PTC CentralReceiver
ParabolicDishes
LFC
Unit plant powerWorking temperaturePeak efficiency (solar-electric) Yearly net Efficiency
15-200 MW390 ºC20 %
11-16 %
15-100 MW575 ºC23 %
7-20 %
9-25 kW750 ºC30 %
12-25 %
15-200 MW390ºC
1813
Current status
Technological riskStorage availabilityHybrid designs
Available
LowSiSi
Available
LowSiSi
Prototypes-Demonstration
LowSiSi
Available
High-MediumSiSi
Solar Thermal Electricity Plants