August 2013 MANAGER OF ENGINEERING, BLACK & VEATCH, SOUTH AFRICA KEVIN MILLER HYBRID SOLAR THERMAL INTEGRATION AT EXISTING FOSSIL GENERATION FACILITIES

AGENDA Solar Thermal Integration at Existing Rankine Cycle Generating Facilities [HYBRID CSP] Solar Integration with Coal / Oil Steam Plants 2

Integrated Solar Combined Cycle adds steam to the Rankine Cycle CONCEPTS OF COMBINED BRAYTON / RANKINE CYCLE GENERATION 3 Rankine CycleBrayton Cycle

Steam produced from renewable source Reduces use of natural gas or light oil No additional capacity (MW) will result from the operation of the solar thermal facility HYBRID CONCEPTS OF INTEGRATED SOLAR THERMAL (ICSS) 4

More efficient with lower capitol cost Solar energy can be converted to electric energy at a higher efficiency. Capital costs are lower than for a CSP-only facility of similar size. Minimal additional plant staff is required A hybrid plant does not suffer from the thermal inefficiencies associated with the daily startup and shutdown of the CSP facility Potential reduction in fuel costs (fossil fuel input / MWh will decrease) Significant reduction in carbon emissions / MWh WHY CONSIDER HYBRID CSP? August 2013Eskom CSP Workshop 5

Located in area of high Direct Normal Solar Irradiation (DNI) Adequate space available Allocation of approximately 2.75 Hectares / Mw KEY CHARACTERISTICS OF CANDIDATE FACILITIES FOR ADDITION OF HYBRID CSP August 2013Eskom CSP Workshop 6

DIRECT NORMAL IRRADIATION (DNI) August 2013Eskom CSP Workshop 7

Black & Veatch was Owner’s Engineer on the addition of 75 MW of CSP steam generation at Martin Station Area with high Direct Normal Solar Irradiation (DNI) Available adjacent land area (202 hectare) Available steam turbine capacity Reduction in associated fuel cost & carbon emissions INTEGRATION OF CSP AT AN EXISTING GAS TURBINE COMBINED CYCLE FACILITY IN FLORIDA, USA August 2013Eskom CSP Workshop 8

MARTIN NEXT GENERATION SOLAR ENERGY CENTER August 2013Eskom CSP Workshop Source; John Van Beekum for The New York Times 9

Martin Next Generation Solar Energy Center was, until recently, the second largest solar-thermal facility in the world and the largest solar plant of any kind outside of California Facility may be the first hybrid facility in the world to connect a solar facility to an existing combined-cycle power plant Provides 75 megawatts of solar thermal capacity Designed to produce an average of 155,000 MWh of electricity annually The expected reduction of system-wide green-house gas emissions is projected to be approximately 2.75 million tons over a 30-year period MARTIN NEXT GENERATION SOLAR ENERGY CENTER August 2013Eskom CSP Workshop 10

COMBINED CYCLE GENERIC LAYOUT August 2013Eskom CSP Workshop HPSHHPSH RH RH HPECHPEC HPECHPEC IPSHIPSH IPECIPEC LPSHLPSH LPECLPEC Steam Turbine Gas Turbine Air Fuel Heat Recovery Steam Generator Air-Cooled Condenser LPEVLPEV IPEVIPEV HPEVHPEV HPECHPEC HP IP / LP LP Steam Hot Reheat Cold Reheat Main Steam IP Steam HP Steam BFP Duct Firing 11

Admit Steam In LP Circuit Admit Steam Into Cold Reheat Admit Steam Into Hot Reheat Admit Steam Into HRSG HP Circuit Between Evaporator and Superheater Admit Main Steam POTENTIAL SOLAR STEAM INJECTION POINTS August 2013Eskom CSP Workshop The most efficient use of solar energy is displacing saturated steam production at the highest pressure. The least efficient use of solar energy is feedwater preheating and steam superheating The most efficient use of solar energy is displacing saturated steam production at the highest pressure. The least efficient use of solar energy is feedwater preheating and steam superheating 12

Parabolic Trough Technology was selected by the Client TYPICAL ACHIEVABLE STEAM TEMPERATURES Parabolic Trough Fluid: Synthetic oil; HTF Temperature: 748ºF (398ºC) Steam Temperature - ~715 F Central Receiver Fluid: Steam, molten salt, air Steam Temperature: 1025ºF (550ºC) Compact Linear Fresnel Reflector Fluid: Steam Steam Temperature: 520ºF (270ºC) STEAM ADMISSION LOCATIONS DRIVEN BY SOLAR TECHNOLOGY August 2013Eskom CSP Workshop 13

Because parabolic trough systems are more mature commercially and technically. Trough Steam Admission Points: LP, Cold Reheat, HP Steam Between Evap and Superheater Power Tower Steam Admission Points: Could be same as trough, but also allows higher temperature admissions to Hot Reheat or Main Steam Compact Linear Fresnel Reflector LP, Cold Reheat STEAM ADMISSION LOCATIONS DRIVEN BY SOLAR TECHNOLOGY August 2013Eskom CSP Workshop 14

… but when it is being integrated into an existing facility, by the characteristics / capabilities of the existing steam cycle and equipment can become overriding considerations STEAM ADMISSION LOCATIONS DRIVEN BY SOLAR TECHNOLOGY… August 2013Eskom CSP Workshop 15

Extraction point can impact the feedwater temperature further influencing the size of the solar field Boiler Feed Pump (BFP) Discharge HP Economizer Exit with Booster Pump (A unique booster pump may be needed to overcome the additional pressure drop on the HTF water / steam side) TYPICAL FEEDWATER EXTRACTION LOCATIONS August 2013Eskom CSP Workshop 16

FEEDWATER FROM BFP DISCHARGE + HP STEAM ADMISSION USED IN THIS CASE August 2013Eskom CSP Workshop HPSHHPSH RH RH HPECHPEC HPECHPEC IPSHIPSH IPECIPEC LPSHLPSH LPECLPEC Steam Turbine Gas Turbine Air Fuel Heat Recovery Steam Generator Air-Cooled Condenser LPEVLPEV IPEVIPEV HPEVHPEV HPECHPEC HP IP / LP Main Steam HP Steam BFP Duct Firing Solar Field / Solar Power Block BFP Discharge 17

Other configurations are available, including vertical orientations REPRESENTATIVE SOLAR STEAM GENERATOR OUTLINE August 2013Eskom CSP Workshop HTF in HTF out The vessel shown is ~ 15 meters long, 3 meters in diameter In this design there were (3) vessels for each GT / HRSG grouping; Preheater Steam generator (this vessel) Superheater Steam Out 18

Thermal lag time in solar fields is large, 30 minutes or more, due to the large volume of Heat transfer fluid (HTF) and variable HTF flow Cloud cover events result in changing HTF flow as the solar field responds to control HTF outlet temperatures As areas of the solar field see varying levels of cloud cover and the duration of the cloud passage is a variable, the degree the power plant output is impacted is dependant on the magnitude of these events Plants operating in regions with frequent cloud cover should consider these impacts into the design to mitigate operational impacts and to maximize daily solar utilization SOLAR RESOURCE INTERMITTENCY August 2013Eskom CSP Workshop 19

These events can lead to a shut-off of the solar steam generator train(s) (SSGs) if the HTF temperature falls near or below the saturation temperature of the steam supply generator (SSG) evaporators Unlike stand-alone solar plants, the steam pressure of the SSG is driven by the operating load of the CC plant CTGs, not the amount of steam that could be produced if the evaporator was free to slide in pressure IMPACT OF CLOUD COVER ON SOLAR STEAM GENERATION (SSG) OPERATION August 2013Eskom CSP Workshop 20

MARTIN NEXT GENERATION SOLAR ENERGY CENTER August 2013Eskom CSP Workshop Array includes 6,864 Units 192,000 Mirrors Covers approximately 202 ha 21

SOLAR INTEGRATION WITH COAL / OIL STEAM PLANTS 22

TYPICAL STEAM PLANT GENERIC SCHEMATIC August 2013Eskom CSP Workshop Condenser HP IP/LP Cold Reheat Steam Turbine LP FW Heaters HP FW Heaters BFP Deaerator Final Feedwater Main Steam Hot Reheat Condensate Pump Steam Generator (BOILER) Generator 23

CONFIGURATIONS CAN INCLUDE THE FOLLOWING, ALONE OR IN COMBINATION Feedwater heating - External heating Feedwater heating – Provide heating steam Generation of Cold Reheat Steam Generation of Hot Reheat Steam Generation of HP steam Generation of Main Steam POTENTIAL INJECTION POINTS FOR SOLAR- SOURCED THERMAL ENERGY August 2013Eskom CSP Workshop 24

MAXIMUM ACHIEVABLE STEAM TEMPERATURE Parabolic Trough Fluid: Synthetic oil; HTF Temperature: 748ºF (398ºC) Steam Temperature - ~715 F (379ºC) Central Receiver Fluid: Steam, molten salt, air Steam Temperature: 1025ºF (550ºC) Compact Linear Fresnel Reflector Fluid: Steam Steam Temperature: 520ºF (270ºC) STEAM ADMISSION LOCATIONS DRIVEN BY SOLAR TECHNOLOGY, AND ARE THE SAME AS SHOWN PREVIOUSLY FOR THE MARTIN CASE STUDY (TEMPERATURES SHOWN ARE TYPICAL; REPRESENTATIVE) August 2013Eskom CSP Workshop 25

Criteria used in the selection of the solar technology used in a specific plant should include not only the capabilities of the candidate technology, but the steam cycle and characteristics of the existing steam cycle Candidate Trough Steam Admission Points: Feedwater Heating, LP, Cold Reheat, HP Steam Between Evap and Superheater Candidate Power Tower Steam Admission Points: Could be same as trough, but also allows higher temperature admissions to Hot Reheat or Main Steam Candidate Compact Linear Fresnel Reflector Feedwater Heating, LP, Cold Reheat STEAM ADMISSION LOCATIONS DRIVEN BY SOLAR TECHNOLOGY August 2013Eskom CSP Workshop 26

EXTERNAL FEEDWATER HEATING August 2013Eskom CSP Workshop Air-Cooled Condenser HP IP / LP Cold Reheat Steam Turbine LP FW Heaters HP FW Heaters BFP Solar Field / Solar Feedwater Heaters Deaerator Steam Generator Final Feedwater Main Steam Hot Reheat Condensate Pump 27

GENERATION OF HP STEAM August 2013Eskom CSP Workshop Air-Cooled Condenser HP IP / LP Cold Reheat Steam Turbine LP FW Heaters HP FW Heaters BFP Solar Field / Solar Steam Generators Deaerator Steam Generator Final Feedwater Main Steam Hot Reheat Condensate Pump HP Steam to HP Superheater 28

Boiler Feed Pump (BFP) Discharge Final Feedwater exiting Top Feedwater Heater Feedwater extraction location affects supply water temperature to solar steam generation train, the amount of feedwater preheating required in the SSG train, the size of the solar field and the heat balance within the thermal plant steam cycle TYPICAL FEEDWATER EXTRACTION LOCATIONS August 2013Eskom CSP Workshop 29

Hybrid Solar thermal has been applied on large scale basis at an existing combined cycle facility The concept has proven to be operationally acceptable Application at existing coal or oil-fired facilities is technically feasible Designs must consider the steam cycle, where addition of solar generated energy is physically possible, as well as the required temperature and pressure requirements of the cycle SUMMARY August 2013Eskom CSP Workshop 30