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Parabolic dishes * general description * main elements: parabolic concentrator, structure and tracking system, receiver, stirling engine and generator * state of the art: types of dish-stirling systems; operational aspects; performance and economy * future developments Central receiver systems * general description * main elements: heliostat, tower, receiver, power conversion system * state of the art: technology options; operational aspects; performance and economy * future developments
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By Manuel A. Silva Pé[email protected]
April 14, 2010
Concentrated Solar Thermal PowerTechnnology Training
Session 3 – Point Focus Technologies
http://www.leonardo-energy.org/csp-training-course-5-lessons
Session 3. Point Focus Technologies:
Parabolic Dish and
Central Receiver Systems
Manuel A. Silva Pérez
http://www.leonardo-energy.org/csp-training-course-lesson-3-point-focus-technologies-dish-stirling-and-central-receiver-systems
Central Receiver Systems ‐ CRS
http://www.leonardo-energy.org/csp-training-course-lesson-3-point-focus-technologies-dish-stirling-and-central-receiver-systems
Solar Thermal Power Plant. Basic configuration
Beam irradiance
Concentrator
Receiver
Thermal Storage
Concentrated irradianceElectricity
Power conversion system
Thermal energy
BoilerFossil fuel Biomass
http://www.leonardo-energy.org/csp-training-course-lesson-3-point-focus-technologies-dish-stirling-and-central-receiver-systems
Central Receiver System
http://www1.eere.energy.gov/solar/power_towers.html
The heliostat
• “an instrument consisting of a mirror mounted on an axis moved by clockwork by which a sunbeam is steadily reflected in one direction”
• Basic components– Reflecting surface– Structure and tracking mechanism– Control system
• Typology:– Glass ‐metal– Stretched membrane
• Size: 1 m2 to 150 m2
http://www.leonardo-energy.org/csp-training-course-lesson-3-point-focus-technologies-dish-stirling-and-central-receiver-systems
Heliostat
Back support structure
Elevation drive
Azimuth drive
Reflecting surface
Reflected ray
Incident ray
http://www.leonardo-energy.org/csp-training-course-lesson-3-point-focus-technologies-dish-stirling-and-central-receiver-systems
Glass – metal heliostat
http://www.leonardo-energy.org/csp-training-course-lesson-3-point-focus-technologies-dish-stirling-and-central-receiver-systems
Glass – metal heliostat
http://www.leonardo-energy.org/csp-training-course-lesson-3-point-focus-technologies-dish-stirling-and-central-receiver-systems
Glass – metal heliostats
http://www.leonardo-energy.org/csp-training-course-lesson-3-point-focus-technologies-dish-stirling-and-central-receiver-systems
Stretched membrane heliostats
http://www.leonardo-energy.org/csp-training-course-lesson-3-point-focus-technologies-dish-stirling-and-central-receiver-systems
Stretched membrane heliostats
http://www.leonardo-energy.org/csp-training-course-lesson-3-point-focus-technologies-dish-stirling-and-central-receiver-systems
Heliostat field layout
• Surrounding field
• North (south) field
• Secondary concentration
• Secondary concentrator optics tower (SCOT)
http://www.leonardo-energy.org/csp-training-course-lesson-3-point-focus-technologies-dish-stirling-and-central-receiver-systems
North field
0
200
400
600
800
1000
-600 -400 -200 0 200 400 600
http://www.leonardo-energy.org/csp-training-course-lesson-3-point-focus-technologies-dish-stirling-and-central-receiver-systems
Surrounding field
http://www.leonardo-energy.org/csp-training-course-lesson-3-point-focus-technologies-dish-stirling-and-central-receiver-systems
Geometrical performance of heliostats
http://www.leonardo-energy.org/csp-training-course-lesson-3-point-focus-technologies-dish-stirling-and-central-receiver-systems
Cosine factor
Yearly average cosine factor for a north heliostat field
http://www.leonardo-energy.org/csp-training-course-lesson-3-point-focus-technologies-dish-stirling-and-central-receiver-systems
Reflectivity
• Reflectivity of a new, clean mirror ≈ 0.90 ÷ 0.94
Shading and blocking
http://www.leonardo-energy.org/csp-training-course-lesson-3-point-focus-technologies-dish-stirling-and-central-receiver-systems
Atmospheric attenuation
http://www.leonardo-energy.org/csp-training-course-lesson-3-point-focus-technologies-dish-stirling-and-central-receiver-systems
Spillage
http://www.leonardo-energy.org/csp-training-course-lesson-3-point-focus-technologies-dish-stirling-and-central-receiver-systems
CRS – Receiver
• Function: to receive concentrated solar radiation and transform it to thermal power (enthalpy increase of the working fluid)
• Components– (Tower)– (Cavity)– Absorber– Supporting Structure– (Other auxiliary elements: Steam drum, recirculation
pumps...)
http://www.leonardo-energy.org/csp-training-course-lesson-3-point-focus-technologies-dish-stirling-and-central-receiver-systems
Types of receivers for CRS plants
External Cavity
Volumetric (Fluidized bed)
Working fluid Working fluid
Air intake
Solid particlesAbsorber
http://www.leonardo-energy.org/csp-training-course-lesson-3-point-focus-technologies-dish-stirling-and-central-receiver-systems
Cavity
http://www.leonardo-energy.org/csp-training-course-lesson-3-point-focus-technologies-dish-stirling-and-central-receiver-systems
Molten salt cavity receiver
4.5 MWt molten salt receiver tested under a cost shared program with US utilities and industry.
External, cylindrical
http://www.leonardo-energy.org/csp-training-course-lesson-3-point-focus-technologies-dish-stirling-and-central-receiver-systems
External, cylindrical receiver
http://www.leonardo-energy.org/csp-training-course-lesson-3-point-focus-technologies-dish-stirling-and-central-receiver-systems
Receiver – working fluids
• Water / Steam
• Air
• Molten salts
• Sodium
http://www.leonardo-energy.org/csp-training-course-lesson-3-point-focus-technologies-dish-stirling-and-central-receiver-systems
CRS (PS10, sat. steam)
http://www.leonardo-energy.org/csp-training-course-lesson-3-point-focus-technologies-dish-stirling-and-central-receiver-systems
PS10 and PS20 (Abengoa Solar, Spain)
CRS (Gema Solar, Molten salts)
http://www.leonardo-energy.org/csp-training-course-lesson-3-point-focus-technologies-dish-stirling-and-central-receiver-systems
Gema Solar (Torresol Energy, Spain)
http://www.leonardo-energy.org/csp-training-course-lesson-3-point-focus-technologies-dish-stirling-and-central-receiver-systems
Gema Solar
Design Data
Total Reflective Area 285.200 m2
Number of heliostats 2480
Total Area covered by Heliostat Field 142.31 Ha
Thermal output of the Receiver 120 MWt
Tower height 120 m
Heat Storage Capacity (equivalent to turbine operation) 15 hours
Steam Turbine power 17 MWe
Natural Gas Thermal Power 16 MWt
Projected Operative Figures
Direct solar radiation over Heliostats 2062 kWh/m2
Annual Energy sales 96.400 MWhe
Contribution of Natural Gas 15%
Capacity utilization 65 %
CO2 savings 23.000 – 85.000 t/y
CRS: Pros and cons.
• Pros:– Ability to achieve high temperatures– Wide industrial base for most components– Many technological options– Technologically proven– Multiple thermal storage opptions– Great potential for improved efficiency and/or cost reduction
• Cons.:– Complexity– Short commercial record– Still inmature?
http://www.leonardo-energy.org/csp-training-course-lesson-3-point-focus-technologies-dish-stirling-and-central-receiver-systems
Sierra Solar (e‐Solar, USA)
http://www.leonardo-energy.org/csp-training-course-lesson-3-point-focus-technologies-dish-stirling-and-central-receiver-systems
Unit #1 (100 kW hybrid GT) (Aora Solar, Israel)
http://www.leonardo-energy.org/csp-training-course-lesson-3-point-focus-technologies-dish-stirling-and-central-receiver-systems
Parabolic dishes
Parabolic dish systems
• Combine a paraboloidal concentrator (parabolic dish) with a Power Conversion Unit (PCU) directly attached to the concentrator
• Types of PCU– Gas Turbines
– Direct Steam Generation
– Stirling Engine
Advanco ('82-'85)
MDAC ('83-'88) Boeing/SES (‘98-’99)
SBP/Almeria('88-'99)
Cummins('89-'96)
SBP/Solo
SAIC/STM
Solar Village (Arabia Saudí)
http://www.leonardo-energy.org/csp-training-course-lesson-3-point-focus-technologies-dish-stirling-and-central-receiver-systems
Parabolic dish ‐ Direct Steam Generation
Dish collector field at Shenandoah, GA• Industrial process heat project. • 7 meters in diameter, • aluminized film reflector Heat from the field was used in a textile plant for air conditioning and process heat.
Parabolic dish – Stirling engine experiences (source: Mancini et al. JSEE 2003)
Parabolic dish – Stirling engine
•High performance– High concentration ratio
– High temperature
– Modularity
– No water consumption
• Costes todavía por encima de la fotovoltaica
• Reto en la reducción de O+M• Durabilidad del grupo receptor/motor
SBP/Solo-PSA
10-kW EuroDish
Dish – Stirling systems. Main elements
• Structure
• Concentrator
• Tracking system
• PCU
• Control
http://www.leonardo-energy.org/csp-training-course-lesson-3-point-focus-technologies-dish-stirling-and-central-receiver-systems
Structural optical surface
http://www.leonardo-energy.org/csp-training-course-lesson-3-point-focus-technologies-dish-stirling-and-central-receiver-systems
Space frame structures
Stretched membrane
Glass mirror‐faceted
• Spherically curved mirrors
• Individually alignable
• Parabolic shaped structure
http://www.leonardo-energy.org/csp-training-course-lesson-3-point-focus-technologies-dish-stirling-and-central-receiver-systems
Full surface paraboloid
• The entire surface forms a paraboloid
• Usually made of a number of ‘petals’
http://www.leonardo-energy.org/csp-training-course-lesson-3-point-focus-technologies-dish-stirling-and-central-receiver-systems
Stretched membrane. Single facet
• Membrane– Preshaped (vacuum not
enough)
– Thin reflective plastic
– Thin metal sheet + reflective surface
Stretched membrane ‐multifaceted
• Avoid the need for preshaping
• Difficult alignment
Polar tracking
http://www.leonardo-energy.org/csp-training-course-lesson-3-point-focus-technologies-dish-stirling-and-central-receiver-systems
Elevation ‐ azimuth tracking
Receiver
• Absorbs concentrated solar energy and converts it to thermal energy that heats the working fluid (gas) inside the engine.– External (low temp.)
– Cavity (high temp.)
– Directly illuminated tubes
– Reflux
http://www.leonardo-energy.org/csp-training-course-lesson-3-point-focus-technologies-dish-stirling-and-central-receiver-systems
Directly illuminated tubes receiver
http://www.leonardo-energy.org/csp-training-course-lesson-3-point-focus-technologies-dish-stirling-and-central-receiver-systems
Reflux receiver
• Intermediate heat transfer fluid
• Decouple receiver and engine– Pool boiler. The absorbed surface is always immersed in a liquid
http://www.leonardo-energy.org/csp-training-course-lesson-3-point-focus-technologies-dish-stirling-and-central-receiver-systems
Reflux receiver
• Heat pipe. A wick draws the liquid metal from a small sump
http://www.leonardo-energy.org/csp-training-course-lesson-3-point-focus-technologies-dish-stirling-and-central-receiver-systems
Striling Engine
• The Stirling cycle
http://www.leonardo-energy.org/csp-training-course-lesson-3-point-focus-technologies-dish-stirling-and-central-receiver-systems
Stirling engines
• Kinematic
• Free piston
http://www.leonardo-energy.org/csp-training-course-lesson-3-point-focus-technologies-dish-stirling-and-central-receiver-systems
State of the art
• Most efficient solar to electric technology.
• Pre‐commercial experiences– Increase reliability
– Reduce costs
• Three main manufacturres / systems today– Tessera Suncatcher (SES) 25 kW
– Cleanergy / SBP Eurodish 10 kW
– Infinia Corp 3 kW
http://www.leonardo-energy.org/csp-training-course-lesson-3-point-focus-technologies-dish-stirling-and-central-receiver-systems
Tessera Suncatcherhttp://www.tesserasolar.com/
http://www.leonardo-energy.org/csp-training-course-lesson-3-point-focus-technologies-dish-stirling-and-central-receiver-systems
Infiniahttp://www.infiniacorp.com/
• 3 kW Free piston engine
http://www.leonardo-energy.org/csp-training-course-lesson-3-point-focus-technologies-dish-stirling-and-central-receiver-systems
Infinia
http://www.leonardo-energy.org/csp-training-course-lesson-3-point-focus-technologies-dish-stirling-and-central-receiver-systems
Eurodishsbp.de
• 10 kW kinematic Stirling engine (SOLO V161)
• 8.5 m diameter concentrator
http://www.leonardo-energy.org/csp-training-course-lesson-3-point-focus-technologies-dish-stirling-and-central-receiver-systems
Tessera – SES Maricopa Solar Plant (AZ, USA)
http://www.leonardo-energy.org/csp-training-course-lesson-3-point-focus-technologies-dish-stirling-and-central-receiver-systems