Session 5: CSP Overview - 1 Agenda Discussion of Homework Overview Heat Engines Storage Trough Systems Homework Assignment

Learning Objectives 2 Students should be able to Compare CSP vs. PV in meeting customer needs Describe the three basic CSP approaches and their status Explain how steam, gas turbine and Stirling engines work Draw a schematic of a power tower system with thermal storage Modify the above schematic to incorporate a hybrid gas turbine Calculate the cost-of-electricity for a CSP system Compare typical CSP and PV plant supply chains Give examples of current CSP Projects and describe them Predict how CSP technologies will develop in the future Conceptually define a CSP system based on given requirements

Example CSP Plants 3

So What’s New? 4 Dish/Steam Irrigation System circa 1900 at Broadway and the railroad tracks in Tempe, Arizona

Desirable Grid Power High Quality Harmonics Power Factor Available Dispatchable Continuous Low Cost Renewable (Gov. Reqt.) 5

Solar Plant Design Considerations Solar Plant Design Fossil Fuel (?) Solar Input (Variability) Ambient Conditions Water Electrical Power Design Requirements Risk 6

Basic CSP Concept Receiver/Heat Engine Low-level Solar Energy CONCENTRATORCONCENTRATOR Generator High Temperature Energy Low Temperature Heat Sink 7

Heat Engine Efficiency Engines operate on the 2T Principle Carnot efficiency Engines are limited by the Carnot efficiency Goal is to maximize efficiency to reduce collector field size At some point, the cost of higher efficiency increases overall cost Engine W, Useful Work Qout at Tcold Qin at Thot η = Thot – Tcold = 1 – Tcold Thot Thot 8

Power Cycle Efficiencies Source: Summary Report for Concentrating Solar Power Thermal Storage Workshop, NREL/TP August

United States Solar Market 10 Source: SES Presentation to AZ/NV SAE, 2005

International Solar Market 11 Source: SES Presentation to AZ/NV SAE, 2005

Basic CSP Concept Receiver/Heat Engine Low-level Solar Energy CONCENTRATORCONCENTRATOR Generator High Temperature Energy Low Temperature Heat Sink 12

CSP System Elements Concentrator Receiver Heat Engine Generator Balance Of Plant GRID 13

CSP System Elements Concentrator Receiver Heat Engine Generator Balance Of Plant GRID Trough Heliostats (Power Tower) Dish Linear Cavity Tubular Volumetric Rankine Steam Organic Gas Turbine Stirling Combined Hybrid (fossil fuel) Synchronous Induction 14

Types of Concentrating Solar Power Systems Source: Powerpoint Presentation, Muller-Steinhagen et al., Concentrating Solar Power: A Vision for Sustainable Electricity Generation, Institute for Technical Thermodynamics, German Aerospace Center, Stuttgart (DLR) 15

Types of Concentrating Solar Power Systems 16

Types of CSP Systems Single-axis tracking Parabolic troughs Moderate temperature Central engine Moderate efficiency Dual-axis tracking Heliostats Flat facets High temperature Central engine Higher efficiency Dual-axis tracking Parabolic facets High temperature Distributed engines Highest efficiency 17

Types of Receivers Parabolic trough Moderate temperature Power Tower Dish Gas and liquid fluid High temperature Convection losses Power Tower Dish Quartz window Gas working fluid High temperature Low convection losses Linear ReceiverCavity Receiver VolumetricTubular 18

Cavity Receiver Source: SES Presentation to AZ/NV SAE,

Volumetric Receiver Source: Powerpoint Presentation, Muller-Steinhagen et al., Concentrating Solar Power: A Vision for Sustainable Electricity Generation, Institute for Technical Thermodynamics, German Aerospace Center, Stuttgart (DLR) 20

Heat Engines Steam (Rankine) Cycle (30-35% efficient) Gas Turbine Cycle (30-40% efficient) Stirling Cycle (40-45% efficient) TroughPower Tower DishPower Tower Dish Wet Cooling Dry Cooling No Cooling Dry Cooling 21

Steam (Rankine) Cycle Heater Turbine Condenser Cooler Ambient Air P Pump Gen 22

Gas Turbine (Brayton) Cycle Combustor Turbine Ambient Air Compressor Gen Ambient Air Qin from fuel 23

Semi-Closed Brayton Cycle Heater Turbine Ambient Air Compressor Gen Ambient Air Qin 24

Recuperated Semi-Closed Brayton Ambient Air Recuperator Turbine Ambient Air Compressor Gen Qin Heater 25

Stirling Engine is Closer to Carnot In Rankine system, T hot varies, but T cold is relatively constant In Brayton system, T hot varies and T cold varies In Stirling system, T hot and T cold approach constant values For expansion and compression processes: 26

27 Source: SES Presentation to AZ/NV SAE, 2005

CSP System Elements Concentrator Receiver Heat Engine Generator Balance Of Plant GRID 28

CSP System Elements Concentrator Receiver Heat Engine Generator Balance Of Plant GRID Losses 29

CSP System Elements Concentrator Receiver Heat Engine Generator Balance Of Plant GRID Losses η sys = η conc η rec η eng η gen η BOP Sunlight-to-Busbar Efficiency 30

CSP Advantage: Storage Concentrator Receiver Heat Engine Generator Balance Of Plant GRID Storage 31

Storage Advantages Extends operation during peak demand hours Maintains output during transient clouds Provides power on-demand (dispatchable) Source: NREL website 32

Trough Plant Components C A B Source: NREL 33

Power Tower Plant Components A B C Source: NREL 34

Dish/Engine Plant Components A B C Source: SES Presentation to AZ/NV SAE,

Levelized Cost of Electricity Comparison Source: PowerPoint presentation, Brett Prior, November 2011, GTM Research, read/can-solar-thermal-be- cheaper-than-pv/ 36

37 Trough CSP

SEGS Units Solar Electric Generating Systems Mohave Desert, Built Trough/Steam/Evap. Cooling Up to 25% Output from Natural Gas 9 Plants: 14, 30, 80 MWe 354 MWe Total Output Aerial view of five (SEGS III – VII), 30- MW SEGS solar plants Source: NREL 38

SEGS VI: 30 MWe Kramer Junction Start-up: 1988 Field Supply Temp: 390 degrees Celsius Field Size: 188,000 m 2 Luz International KJC Operating Company Figure 1.1. Parabolic troughs at a 30 MWe (net) SEGS plant in Kramer Junction, CA January 2006 Angela M. Patnode “Simulation and Performance Evaluation of Parabolic Trough Solar Power Plants” 39

Solar Field Design Single-axis tracking collector troughs Float-formed, parabolic-curved mirrors Heat collection element (HCE) runs through focal line Thermal energy into heat transfer fluid (HTF) Trough axes north-south Track east to west SOURCE: January 2006 Angela M. Patnode “Simulation and Performance Evaluation of Parabolic Trough Solar Power Plants” Solar Collector Assembly (SCA ) 40

Figure 2.1. Layout of the SEGS VI solar trough field. The superimposed arrows indicate the direction of heat transfer fluid flow. (Photo source: KJC Operating Company, 2005) January 2006 Angela M. Patnode “Simulation and Performance Evaluation of Parabolic Trough Solar Power Plants” SEGS VI Layout 41

January 2006 Angela M. Patnode “Simulation and Performance Evaluation of Parabolic Trough Solar Power Plants” Parabolic Trough Collector End of Row Flexible Joints 42

Figure 2.3. Schematic of a Solar Collector Assembly (SCA) (Source: Stuetzle, 2002) January 2006 Angela M. Patnode “Simulation and Performance Evaluation of Parabolic Trough Solar Power Plants” Overall Trough Collector Design 43

Heat Collection Element (HCE) Steel absorber tube 70 mm in diameter Coated with either black chrome or cermet Vacuum between absorber and glass envelope to limit heat loss Photo source: Solel UVAC,

Heat Transfer Fluid (HTF) Synthetic oil -- mixture of biphenyl and diphenyl oxide (Therminol VP-1) Receives solar energy and transfers it to steam cycle in a three-stage boiler (reheater not shown) Solar Field Superheater Steam Generator Pre-heater Pump Steam Cycle/ Generator 45

Simplified Overall Schematic Source:G. Cohen, Solargenix Energy presentation to IEEE Renewable Energy, Las Vegas, May 16,

Transfer of HTF Energy to Steam Plant Source: January 2006 Angela M. Patnode “Simulation and Performance Evaluation of Parabolic Trough Solar Power Plants” 47

Figure 2.1. Layout of the SEGS VI solar trough field. The superimposed arrows indicate the direction of heat transfer fluid flow. (Photo source: KJC Operating Company, 2005) Source: January 2006 Angela M. Patnode “Simulation and Performance Evaluation of Parabolic Trough Solar Power Plants” SEGS VI Layout 48

SEGS VI: Solar Field Layout Adapted from “Simulation and Performance Evaluation of Parabolic Trough Solar Power Plants” Jan 2006, Angela M. Patnode Steam Heat Exchangers Row of 8 SCAs East Field (25 Parallel Loops) Row of 8 SCAs West Field (25 Parallel Loops) 49

SEGS VI Performance Source: January 2006 Angela M. Patnode “Simulation and Performance Evaluation of Parabolic Trough Solar Power Plants” June 21, 2004 December 21, 2004 Why is Solar Input so low in winter? 50

Trough Plants are Single Axis Tracking Source: January 2006 Angela M. Patnode “Simulation and Performance Evaluation of Parabolic Trough Solar Power Plants” 51

SEGS VI Performance for 1998 Source: An Overview of the Kramer Junction SEGS Recent Performance Scott Frier, KJC OPERATING COMPANY 1999 Parabolic Trough Workshop August 16, 1999 Ontario, California Average Daily Normal Insolation = kWh/m2/day Percentage measured = % Solar DNI Input = 577,200 MWht Gross Electrical Output from Solar Production = 67,358 MWhe Station Use = 11.7% of Gross Energy Net Electrical Output from Solar Production = 59,477 MWhe Overall Efficiency = Net Electrical Out/Solar DNI In = 10.3% Solar Capacity Factor = 22.6% 52

53 Saguaro (near Marana)  Also uses parabolic trough collectors to heat up a “thermal oil heat transfer” fluid, up to 288 °C  Instead of steam, the Rankine cycle uses an organic liquid (pentane) that can boil at a lower temperature  1 MW capacity  No storage capability  Went online in 2006  Open for tours on the last Wednesday of the month ( olarTrough.pdf) Source: Arizona Public Service

54 Saguaro Diagram

55 Saguaro “Power Block”

Homework for Session 6 Review slides for Sessions 6 and 7 Select a current CSP Plant and describe it Two-pages Professional quality Be prepared to discuss in class