Materials for CSP receiversState-of-the-art, R&D requirements and future options

Thomas Fend, German Aerospace Center

10th Liège Conference on Materials for Advanced Power EngineeringSeptember 14th – 17th, 2014Liège, Belgium

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Outline

• Introduction to CSP• Parabolic Trough technology

• Indirect HTF loop (oil)• Direct steam• Indirect HTF loop (liquid salt)

• Tower technology• Direct steam• Molten salt steam• Volumetric air• Solar gas turbine

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CSP: Concentrated Solar Power

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Electr.Solarirradiation

Heat

Solar fieldPowerplant

Grid

FuelProcess heat

- optional thermal storage - hybrid operation - heat extraction for process heat, cooling, desalination

StorageStorageStorageStorageStorage

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Solar tower (SNL)

Dish-Stirling (SBP) Linear Fresnel (MAN/SPG)

Up

to10

00°

C G

as tu

rbin

es

Up

to 5

50°

C s

team

turb

ines

Parabolic trough (PSA)

CSP: Concentrated Solar Power

CSP world map

Worldwidein operation: 4,2 GWforecast 2020: 15,5 GWforecast 2050: 1070 GW

Parabolic Trough Technology: Indirect with Heat Transfer Fluid (HTF)

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Source: Solar Millennium AG

Parabolic Trough Technology indirect HTF:Absorber Tube

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Source: Schott Solar

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Parabolic Trough Technology indirect HTF: Status Quo

Technology Readiness Level (TRL): high, >25 plants commercially operatedSuppliers: Schott, Archimede, Solel…Temperatures:  T < 400°CMaterials: Iron based standard alloys

Further developments:‐ Direct Steam Generation (T < 550°C)‐ Liquid salt as HTF (T< 550°C)Required research action:‐ Qualification‐ Lifetime prediction

Tower Technology: Direct Steam Generation

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Tower Technology: Direct Steam Generation

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TRL: high: 2 plants commerciallyoperating

Suppliers: AbengoaSteam Temp.:   T =280°CMaterials: Iron based alloys

Further developments:‐ Larger plants (Khi Solar one, 50 MW)‐ Higher temperatures (superheated steam) ‐ Increase storage capacityRequired research action:‐ Improved absorber tubes (thermal 

conductivity, heat transfer)

Tower Technology: Molten Salt System

Tower Technology: Molten Salt System

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Foto: Torresol

material load parameters: pressure: ambient max. temp.: ~ 620C (film) max. heat load: ~ 800kW/m²

dynamic operation: wall temp.: 2.8K/sec

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Tower Technology: Molten Salt System

TRL: high, 1 plant commerciallyoperating

Suppliers: Fine Tubes, Sener, Temperatures:  T < 620°CMaterials: Iron based alloys

Further developments:‐ Higher Temperatures

Required research action:‐ Lifetime issues‐ Innovative heat transfer fluids

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Tower Technology: Volumetric Air Receiver

0.02 m²

> 100 m²

0.57 m² 5.7 m²

gas

volumetric receiver

concentratedsolar radiation ~ 1000 kW/m

2

Bild: KAM

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Tower Technology: Volumetric Air Receiver:Improved Porous Receiver Materials

Tower Technology: Volumetric Air Receiver

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TRL: middle,  1 experimental plantSuppliers: SGIK, Kraftanlagen München Temperatures:  600°C  < T < 1000°CMaterials: Porous Silicon Carbide, 

standard high temperaturesteel, nickel base alloys

Further developments:‐ Higher efficiencies,  higher cell densities

lower costs

Required research action:‐ Improved receiver geometry‐ Lifetime issues

Tower Technology: Solar Gas Turbine

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[1] Kribus et al., A solar driven cc power plant, Solar Energy 62, no 2, p 121‐129, 1998[2] Röger, Marc: EnerMENA Video Tutorials, Solar Tower Technology 

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Tower Technology: Solar Gas Turbine

• Absorption• Conductive thermal resistance in 

tube wall• Convective thermal resistance

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Tower Technology: Solar Gas Turbine

• Increased heat transfer surface• Enhanced heat transfer by gradation

in radial direction• Thermal properties of porous

material needed• Proposed by Korean/Swiss/German 

consortium in the project CMC4CSP

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Tower Technology: Solar Gas Turbine

• Increased heat transfer surface• Enhanced heat transfer by gradation

in radial direction• Thermal properties of porous

material needed• Proposed by Korean/Swiss/German 

consortium in the project CMC4CSP

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Tower Technology: Solar Gas Turbine

• Increased heat transfer surface• Enhanced heat transfer by gradation

in radial direction• Thermal properties of porous

material needed• Proposed by Korean/Swiss/German 

consortium in the project CMC4CSP

T fluid6 105 Pa530 °C porous in-lay

398 W

regular tube115 W

„Power on Aperture“ (@400 kW/m²): 800 W

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Tower Technology: Solar Gas Turbine

TRL: low,  technologydemonstrated

Suppliers: EnginCerTemperatures:  800°C < T < 1300°CMaterials: Silicon Carbide Ceramics

Further developments:‐ Higher Temperatures‐ Up‐scaling , larger demonstration plants‐ Solar only operation

Required research action:‐ Improved receiver materials‐ System integration

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