1. Initial Performance History - O&M Lessons Learned
Kuno Schallenberg
26 August 2013
Lahmeyer International GmbH Engineering and Consulting Services Energy Division; Business Unit Renewables and Economics

2. Solar Tower Technology
Brief facts on the current status:
3 operational projects considered commercial:
PS-10 (10 MW)
PS-20 (20 MW), and
Gemasolar (20 MW)
Large commercial projects under construction (e.g. Ivanpah)
Some pilot and demonstration experiences around the world (e.g. Solar One, Solar Two, Themis, etc.)

3. Tower Project Focus: Gemasolar (Spain)
Source: Torresol

4. Gemasolar: Key Data
Source: Torresol

5. Gemasolar: Layout
Decoupled System
Source: Torresol

6. Gemasolar: Plant behaviour (full summer week)
Meinel DNI (W/m²)
Actual DNI (W/m²)
Heliostats focusing (u)
Receiver Power (MWt)
Storage Level (%)
Gas use (kg/s)
Net Output (MWe)
Source: Torresol

7. Gemasolar: Operation - Preliminary Results
Plant is still on ramp-up period (2nd operational year)
Performance exceeds expectations on clear sky days but is lower than expected on cloudy days
Plant can operate continuously 24 hours/day (mainly summer)
Fine control of solar field and receiver temperature achieved
Cleanness factor of the solar field exceeds 95%
Storage tanks loose around 1°C/day in average
Water consumption per year rounds 400,000 m³

8. Gemasolar: Operation Event – Frozen Receiver
Event: Frozen salts on receiver tubes
Cause: operation exceeding boundary conditions (high winds)
Solution: gradual heating of the tubes using the solar field
Result: salts were melted and tubes freed
Consecuences: no mechanical or structural damages to the receiver
Source: Torresol

9. Gemasolar: Maintenance
Source: Torresol

10. Gemasolar: Maintenance – Key Facts
Typical maintenance activities: preventive, predictive and corrective
Major emphasis on predictive maintenance, especially on non-conventional equipment (e.g. receiver, salt pumps, etc.)
Annual plant inspection (scheduled corrective maintenance) with a duration of 3-4 weeks
Turbine has shown no signs of degradation, performing substantially better than in other CSP plants
No perceived degradation on Receiver
No special maintenance activities on salt system (no corrosion noted)
Exceptions: valves (salt system) and kettle

11. Gemasolar: O&M Personnel
Operation (on site):
Around 20 employees which include supervisors, EHS, process engineers and operators, divided into 5 shifts
Maintenance:
Around 30 employees which include supervisors, electromechanical technicians, chemical engineer and cleaning crews

12. Gemasolar: O&M Costs

13. Trough Technology Brief facts on the current status:
Around 3 GW installed worldwide
Large commercial projects still announced
Almost 30 years of operational track record (SEGS I built on 1984)
Relatively mature O&M experience

14. Trough Project Focus: Typical 50 MW installation with TES (Spain)
Source: Torresol

15. Trough Case Study: Key Data
Source: Torresol

16. Trough Case Study: Typical Plant Layout
Source: Torresol

17. Trough Case Study: Plant behaviour (clear and cloudy days)
Stored Energy
Gas Heater
Turbine Output
Source: Torresol

18. Trough Case Study: O&M Results - Spain
Performance results are not similar/homogeneous within the plants installed recently (last 5 years) in Spain
Some plants register 15 to 20% higher annual performance compared to expected values
Experience from SEGS plants allowed optimization of O&M e.g. high performance, effective maintenance (predictive) and cost reduction
Major O&M incidents relate to HTF leakages (e.g. ball joints, flexible hoses), HTF pumps failure, HTF filtration into water/steam cycle, broken absorber tubes
There are no major incidents with the operation of the TES reported

19. Conclusions & Lessons learned
Operation with molten salt systems as HTF is more delicate on changing weather conditions (e.g. cloud passages)
Decoupled systems with TES allow reduction and/or elimination of weather disturbances on the solar field (e.g. cloud passages), allowing a better operation of the turbine
No special events detected on the operation of molten salt storage systems
O&M cost reductions on existing plants are very unlikely without losing plant performance
Increasing project size or multiproject development might be the only way to reduce O&M costs
CSP integration to existing thermal power plants represent a significant reduction on O&M costs for the solar part (e.g. almost no additional labor)

20. Thank you for your Attention
Questions?