Session 7: CSP Part 2

Agenda• Discussion of Homework• Power Tower• Dish/Engine• Hybrid Systems• Homework Assignment

CSP: Power Tower

2

Power Tower with Storage

290 C(554 F)

565 C(1049 F)

• Sun-tracking mirrors• Tower mounted receiver• Storage fluid: Molten salt• Salt/Steam heat exchanger• Conventional steam plant

Source: NREL website

3

Power Tower Characteristics• Solar Multiple = thermal power from collector field peak thermal power for power block

• For a plant in Mohave Desert• Solar Multiple = 2.7• Capacity Factor = 65% (w/o storage, CF =25%)

• Storage Provides• Dispatchability• Accommodate transient clouds• Ability to operate during peak load demand periods

4

Power Tower Pros and Cons

• Pros• Dispatchable• Cover Peak Demand• Accommodate clouds• Good efficiency

• Cons• Not modular, can’t provide power until complete• Not viable for small power output

5

Power Tower History

Source: NREL website

6

Solar TwoBarstow, CA

Goal: Demonstrate Molten Salt Storage

Source: NREL website

7

Solar Two Performance• Receiver: Boeing’s Rocketdyne Division

• Handle Transients: 290 C to 570 C in less than 1 minute (transient clouds)

• Salt• 60% sodium nitrate, 40% potassium nitrate• Melts at 220 C (428 F)• Low viscosity (similar to water)• High wetting factor (hard to contain)

8

State-of-Art: Gemasolar

• Output: 19.9 MWe, 110 GWh/year• • Storage: 15 hours, molten salt

• 140-meter high tower

• 2650 120-m2 heliostats

• Initial Operation: May 2011

• Location: Spain

• Owner: Torresol Energy

Sources: http://www.nrel.gov/csp/solarpaces/project_detail.cfm/projectID=40,http://en.wikipedia.org/wiki/Gemasolar

9

Dish/Engine CSP

10

How do these relate to CSP?

Source: NASA Photo

Source: Kockums Website

11

12

Dish/Stirling Based on these TechnologiesMacDonald Douglas Aircraftdeveloped a dish based on aircraft structural design

Kockums developed a Stirlingengine design based on an Air Independent Propulsion system for submarines

Source: Kockums Website

Source: SES Presentationto AZ/NV SAE, 2005

13

Dish-Stirling ApproachStirling Energy Systems, Inc.

Source: SES Presentationto AZ/NV SAE, 2005

14

Relative Advantages Of Dishes Vs. Other Concentrating Technologies

• Distributed Generation AND Central Power Plant Capabilities

• Minimal Water Usage• Easier To Site And

More Environmentally Friendly:– No Site Leveling Required– No Defoliation

15

Solar Dish Stirling OperationSolar Dish Stirling Operation• Dish Concentrator Focuses Sun’s Energy On Receiver• Stirling Engine Converts Thermal Energy To Electrical Energy

Source: SES Presentationto AZ/NV SAE, 2005

16

Dish Stirling Principles of Operation• Dish Concentrator Focuses Sun’s Energy On Receiver• Stirling Engine Converts Thermal Energy

To Electrical Energy

Source: SES Presentationto AZ/NV SAE, 2005

17

Dish Stirling - Twice AsEfficient As Next Best Solar

3

2.5

2

1.5

1

0.5

00 2 4 6 8 10 12

Sun Daily Energy Per Unit Area (kW hr/sq m)

ESTIMATED ANNUAL ENERGYSolar Dish Stirling 629 kWh/m2Central Receiver 327 kWh/m2Parabolic Trough 260 kWh/m2Tracking Photovoltaic 217 kWh/m2

Dai

ly G

ener

ated

Ene

rgy

Per U

nit A

rea

(kW

hr/

sq m

)

Solar Dish StirlingSolar Dish Stirling

CentralReceiverCentral

Receiver

ParabolicTrough

ParabolicTrough

Tracking PhotovoltaicTracking Photovoltaic

Source: Southern California Edison and Sandia National Laboratories

Solar-to-Bus bar Peak Efficiency-30%

PARA

SITI

C

30.0

GEN

ERAT

OR

31.4

PCU

EN

GIN

E

33.3

RECE

IVER

TEM

P.D

IF

78.

9

RECE

IVER

7

9.3

AVA

ILAB

LE IR

RAD

IAN

CE

100

INTE

RCEP

T

88.1

REFL

ECTI

VITY

91.1

0

20

40

60

80

100

100 91.1 96.7 90 99.5 42 94.8 95.5SUBSYTEM EFFICIENCY

POW

ER P

ERFO

RMAN

CE

(%)

18

Dish Receiver ParasiticsSource: SES Presentationto AZ/NV SAE, 2005

19

SES Dish Stirling System Characteristics

• Concentrator Glass Area..................91.01 m2 (979.72 ft2) @82 mirrors• Receiver Aperture…………………… 8 in diameter; 0.349 ft2 area• Concentration Ratio………………… 2704• Design Wind Speed-Operating……. 30 mph-Survival…..90 mph• Mirror Type…...................................Silvered glass; 0.7 mm thick• Reflectivity…………………………… >91% • Module Height………………………. 11.89 m (39 ft)• Module Width……………………….. 11.28 m (37ft)• Module weight………………………. 14,900 lbs• Sunlight-to-busbar efficiency……… 29.4 percent (at 1000 watts/m2)

Source: SES Presentationto AZ/NV SAE, 2005

20

Source: SES Presentationto AZ/NV SAE, 2005

CONNECTING PISTONS TO A CRANKSHAFT

Source: SES Presentationto AZ/NV SAE, 2005

22

Stirling Engine and Receiver

Source: SES Presentationto AZ/NV SAE, 2005

23

Kockums 4-95 Stirling Engine

Source: SES Presentationto AZ/NV SAE, 2005

24

Kockums 4-95 Stirling EngineKockums 4-95 Stirling Engine

Source: SES Presentationto AZ/NV SAE, 2005

25

Kockums 4-95 Engine Key Parameters• Net Power Rating...................... 25kW at 1000W/m2 insolation• Electrical Power….................... 480, 60 Hz, 3 Phase• Generator........ 1800 rpm induction• Engine Type……. Kinematic Stirling• Number of Cylinders…… Four Double-Acting Pistons• Displacement……………. Each Piston at 95cc• Operating Speed……….. 1800 rpm• Working Fluid……… Hydrogen• Engine Temperature…… 7200 C (13280F)• Engine Pressure………. 20 MPa• Power Control………… Variable Pressure• Cooling……………… Water/Air Radiator• Coolant Temperature…. 500C (1220+F)• Power Conversion Weight… <1500 lbs

Source: SES Presentationto AZ/NV SAE, 2005

Installation of SES Dish at UNLV

26

The History of Stirling Energy Systems1996 SES buys Dish design and hardware from MacDonald

Douglas /California Edison

1997 SES licenses Stirling engine technology from Kockums

2004 SES redesigns Dish

2005 SES installs 6 units at Sandia Nat’l Labs, Albuquerque,

N.M.

2006 SES signs PPAs for 800 MWe with 2 California utilities

2007 SES redesigns both Engine and Dish

2010 SES installs 60 units in Peoria, AZ

2011 SES files Chapter 7 Bankruptcy due to falling PV prices and global financial issues

27

The Future of Dish/Engine• Stirling engine long-term reliability not proven

• Hybrid gas turbine system is being developedby several companies

• Dish can be used for concentrated PV (CPV)

Source: SunLab

28

Southwest Solar TechnologyHybrid Fossil – Solar Brayton

• Largest commercial solar dish in the world

• 320 sq m of aperture area

• 250 kW thermal power

• focus diameter 0.5 m

• Tracking accuracy is within 0.1 deg

Source: SST

29

SST: I-10 and Salt River

Source: SST

30

Hybrid and Advanced Systems

31

Hybrid Fossil Fuel System• Relatively easy to put in-line for trough and power tower• Difficult to introduce with dish/Stirling• Relatively easy to put in-line with dish/Brayton

Source:G. CohenSolargenix Energypresentation to IEEE RenewableEnergy, Las Vegas, May 16, 2006

32

Hybrid Fossil Options• Topping: Needed to get higher input temperature to engine• Supplemental: Provides additional energy when needed• Stand Alone: Provides all power input if needed

Source:G. CohenSolargenix Energypresentation to IEEE RenewableEnergy, Las Vegas, May 16, 2006

33

Trough Storage/Hybrid Concept

Source: Overview on Thermal Storage Systems, Ulf Herrmann et al., FLABEG SolarInternational GmbH, Workshop on Thermal Storage for Trough Plants, February 20-21,

2002.

34

Air Receiver with Storage

Source: Romero, M. et al., An Update on Solar Central Receiver Systems, Projects, and Technologies. Journal of Solar Engineering, May 2002, Vol. 124, 98-104.

35

Power Tower Gas Turbine Plant

Source: Schwarzbozl, P., et al.Solar gas turbine systems: Design, cost and perspectives.Solar Energy 80 (2006) 1231-1240.

36

Power Tower Combined Cycle

Source: Schwarzbozl, P., et al.Solar gas turbine systems: Design, cost and perspectives.Solar Energy 80 (2006) 1231-1240.

37

Hybrid Power Tower Combined Cycle ConceptSolar Air Preheating

Source: Romero, M. et al., An Update on Solar Central Receiver Systems, Projects, and Technologies. Journal of Solar Engineering, May 2002, Vol. 124, 98-104.

38

Conceptual Design with Solar TurbinesRecuperated 3.5 MWe Gas Turbine

Source: Schwarzbozl, P., et al.Solar gas turbine systems: Design, cost and perspectives.Solar Energy 80 (2006) 1231-1240.

39

Reflective Tower Concept

Source: Romero, M. et al., An Update on Solar Central Receiver Systems, Projects, and Technologies. Journal of Solar Engineering, May 2002, Vol. 124, 98-104.

40

Solarization of Honeywell 75 kWeParallon Microturbine

41

Homework Assignment

• Prepare for quiz over CSP• Review slides for next lecture