1. Modelling of Tower Based Concentrating Solar Power Plants: Gemasolar and Ivanpah
Monika Topel, Björn Laumert
kth, royal institute of technology
department of energy technology
Heat and Power Division
Monika Topel, KTH-EGI CSP Group
Stockholm, April, 2013

2. Contents Introduction Tower-based CSP plants Power plant modeling
Obtained Results
On-going work and conclusions

3. We don’t have a resource problem we have a conversion problem.
Introduction
Every half hour, there is enough sunlight on the surface of the Earth to meet all the energy demands on the entire world for one full year.
The amount of incoming solar radiated energy to planet Earth is far greater than any other current energy source
solar energy: part of the solution of the fore mentioned issues
Solar energy technologies
We don’t have a resource problem we have a conversion problem.

4. Concentrating Solar Power (CSP)
Introduction
Solar Field
Power block
Heliostats
More specifically, concentrating solar power (CSP), with its unique capability among renewables to provide dispatchable energy,
great potential for supplying the electricity needs of numerous countries in the sun-belt regions of the world.
Thermal energy storage Dispatchability due to heat conversion.
Conventional power cycle: Rankine
Turbo Power Context
OPTISTEAM
Start-up cycles
Steam turbine transients
Operational improvements
Concentrating Solar Power (CSP)
Solar Radiation  Heat Electricity

5. Tower-based csp plants
Predecessor
Parabolic troughs (1st )
Point-focusing system
Higher concentration ratios
Higher temperatures
4% of global installed CSP share
98MW
603 MW in the coming 2 years
Heliostats
Recent market trends indicate that CSP tower technologies will play an increasingly prominent role within the CSP landscape.
During the last 10 years, CSP tower-based plant configurations have been introduced on the market.
Compared to conventional parabolic trough-based technology, tower-based technologies enable considerable efficiency gains as the power block can be run at higher operating temperatures.
Within the range of existing solar tower power plant, there are two which are relevant to this work: Gemasolar and Ivanpah.
The two fore mentioned CSP plants are steam turbine based configurations, which have been designed based on leading edge technologies on the solar side.

6. Tower-based csp plants
Reheater
Superheater
Evaporator
Economizer
Molten salt
tanks
Steam
Water
Gemasolar
Status
Operational
Year
2011
Location
Seville, Spain
Storage
15h, Salts
Capacity
19.9 MW
Turbine
SST-600
Inlet Conditions
105 bar/542oC
Gemasolar was the first commercial-scale plant in the world to apply central tower receiver and molten salt thermal energy storage (TES) technology.

7. Tower-based csp plants
Reheater
Superheater
Evaporator
Economizer
Molten salt
tanks LP
Pre-heaters HP
De-aereator
Condenser ~
Gemasolar was the first commercial-scale plant in the world to apply central tower receiver and molten salt thermal energy storage (TES) technology.

8. Tower-based csp plants
Reheater
Superheater
Evaporator
Steam
Water
Ivanpah
Status
Operational
Year
2013
Location
California, US
Storage
Capacity
377MW (x3)
Turbine
SST-900
Inlet Conditions
160 bar/545oC
Ivanpah, on the other hand, is based on direct steam generation (DSG) which eliminates the usage of different heat transfer fluids in the power block and therefore allows for higher thermal efficiencies.
Given that both of these power plants operate with Siemens steam turbines and consequently their study and modeling is encompassed within the framework of the on-going Turbo Power research project related to steam turbine optimization for solar thermal power plant operation (OPTISTEAM).

9. Tower-based csp plants
Reheater
Superheater
Evaporator LP
Pre-heaters HP
De-aereator
Condenser ~
Ivanpah, on the other hand, is based on direct steam generation (DSG) which eliminates the usage of different heat transfer fluids in the power block and therefore allows for higher thermal efficiencies.
Given that both of these power plants operate with Siemens steam turbines and consequently their study and modeling is encompassed within the framework of the on-going Turbo Power research project related to steam turbine optimization for solar thermal power plant operation (OPTISTEAM).

10. Tower-based csp plants
Complex tracking system
Solar field sizing limitations
Non-mature technology
Non-standard manufacturing
Receiver design
Water and land usage
Steam cycle in locations of high irradiations (deserts)
Parasitic consumption in tower pumping
Efficiency degradation as a result of transient operation
Start-up and shutdown
Although this technology is on the rise is still facing critical issues.

11. Power Plant modelLing LP ~
Solar resource: fluctuating and intermittent
Turbine transient operation Turbine thermal model
Boundary conditions to the turbine
Reheater LP
Superheater ~ HP
Evaporator
Condenser
Economizer
So if we go back to our power cycle side
Pre-heaters
De-aereator
Pre-heaters

12. Power Plant modelLing Dynamic Energy System Optimizer (DYESOPT)
Inlet conditions to the turbine from dynamic simulation

13. Power Plant modelLing Gemasolar Cost function study on-going
CSP-group (TESCONSOL)
Cost function study on-going

14. Power Plant modelLing Ivanpah Planned development of SST-900 as well
Supervision of MSc. thesis
Planned development of SST-900 as well

15. Power Plant modelLing
Inlet conditions to the turbines from dynamic simulation

16. Obtained results
No storage
SM=1.2
Storage: 15h
SM=3

17. On-going WORK
“Impact of Increasing Steam Turbine Flexibility on the Annual Performance of a Direct Steam Generation Tower Power Plant”
Modeling: Ivanpah+SST-900
Turbine enhacenments
Temperature maintaining modifications
Operational modifications
Compare different cases
Power plant Performance indicators
Turbine start-up.
MSc. Thesis

18. On-going WORK
Qin

19. Size the solar field for the Irradiance of the location
On-going WORK
Oversized solar field (SM>1)
SM=1 Solar field size design for nominal power block Qth
Oversized solar field (SM<1)
Size the solar field for the Irradiance of the location

20. On-going WORK Over Load SM>1 Part Load SM<1
HP stage bypass + Feed water heater bypass
HP stage bypass + HP feed water top heater
from boiler
HPT
pre-heater
water side
to boiler
to boiler
from boiler
HPT
pre-heater
water side
top heater

21. Conclusions (Future work)
WP2: CSP plant in DYESOPT
Ivanpah model completed (05/2014)
Cost function study (06/2014)
To complete Gemasolar model
D2.1: Report on Steam turbine operating conditions in tower based CSP (05/2014)
WP3: Steam Turbine Model for Tower Based Plants
SST-900 thermal model (05/2014)
Model fine-tuning (06-07/2014 @FSP)
Research papers: 2 papers with the CSP plants models (SolarPACES2014)
Licentiate Thesis: 10/2014

22. End of Presentation. Thank you for your attention
Modelling of Tower Based Concentrating Solar Power Plants: Gemasolar and Ivanpah
Monika Topel, Björn Laumert
kth, royal institute of technology
department of energy technology
Monika Topel, KTH-EGI CSP Group
Stockholm, April, 2014