Solar energy generating system (SEGS)

This entry was compiled, edited and written by: Cutler Cleveland

Solar Energy Generating Systems (SEGS) is the name given to nine solar power plants in California's Mojave Desert that use parabolic trough technology to generate electricity. SEGS III-VII are located at Kramer Junction, SEGS VIII-IX at Harper Lake and SEGS I-II at Daggett respectively. Collectively, these plants constitute the largest concentration of solar power generation capacity in the world.

Kramer Junction solar electric generating stationKramer Junction solar electric generating station

A parabolic trough solar power plant uses a large field of parabolic collectors to supply thermal energy to a conventional electric power plant. Because they use conventional power cycles, parabolic trough power plants can be hybridized—other fuels can be used to back up the solar power. Like all power cycles, trough power plants also need a cooling system to transfer waste heat to the environment.

The cost of electricity from parabolic trough solar power plants is significantly higher than that from coal and natural gas plants. However, the costs of solar power have declined in the recent past, and will continue to decline due to technological improvements. Costs reductions will occur if appropriate government incentives are available and if the elimination of barriers encourage widespread deployment of SEGS. Compared to fossil-fueled power plants, parabolic trough power plants generate significantly lower levels of greenhouse gases and other emissions. Such costs are not typically included in the economic comparison of power generation systems.

Geographic location of plants

  • SEGS I and II: 34°51′47″N 116°49′37″W
  • SEGS III through VII: 35°00′51″N 117°33′32″W
  • SEGS VIII and IX: 35°01′54″N 117°20′53″W

SEGS Power Plant Data

Plant Name Location First
Year of
Operation
Net Output
(MWe)
Solar Field Outlet
(°C)
Solar Field Area
(m2)
Solar Turbine Effic.
(%)
Power Cycle Dispatchability Provided By
SEGS IX Harper Lake, CA 1991 80 390 483,960 37.6 100 bar, reheat HTF heater
SEGS VIII Harper Lake, CA 1990 80 390 464,340 37.6 100 bar, reheat HTF heater
SEGS VI Kramer Junction, CA 1989 30 390 188,000 37.5 100 bar, reheat Gas boiler
SEGS VII Kramer Junction, CA 1989 30 390 194,280 37.5 100 bar, reheat Gas boiler
SEGS V Kramer Junction, CA 1988 30 349 250,500 30.6 40 bar, steam Gas boiler
SEGS III Kramer Junction, CA 1987 30 349 230,300 30.6 40 bar, steam Gas boiler
SEGS IV Kramer Junction, CA 1987 30 349 230,300 30.6 40 bar, steam Gas boiler
SEGS II

Daggett, CA

1986 30 316 190,338 29.4 40 bar, steam Gas boiler
SEGS I Daggett, CA 1985 13.8 307 82,960 31.5 40 bar, steam 3-hrs TES

 

Individual plant descriptions

SEGS IX
Location: Mojave Desert, Harper Lake, California
First Year of Operation: 1991
Type: Solar electric generating station (SEGS); solar steam generation and solar superheating; auxiliary natural gas heat transfer fluid heater to provide backup capability during low and non-solar hours
Fossil fuel: Natural gas
Net Output: 80 MW
Principals: FPL Energy (owner/operator), Luz (developer), Southern California Edison (utility PPA)
Solar Technology: Luz LS-3 collectors
Project Type: Public Utility Regulatory Policies Act (PURPA) Qualifying Facility IPP with Standard Offer 2 (SO-2) type power purchase agreement to Southern California Edison
Operational Dispatch: Solar operation during sunny hours. Natural gas backup operated to augment solar during summer peak from 12 p.m. to 6 p.m. as necessary and during mid-peak hours.
Special Incentives: Federal and state investment tax credits, solar property tax exclusion, and accelerated depreciation.
Status: Daily operation

SEGS VIII
Location: Mojave Desert, Harper Lake, California
First Year of Operation: 1990
Type: Solar electric generating station (SEGS); solar steam generation and solar superheating; auxiliary natural gas heat transfer fluid heater to provide backup capability during low and non-solar hours
Fossil fuel: Natural gas
Net Output: 80 MW
Principals: FPL Energy (owner/operator), Luz (developer), Southern California Edison (utility PPA)
Solar Technology: Luz LS-3 collectors
Project Type: Public Utility Regulatory Policies Act (PURPA) Qualifying Facility IPP with Standard Offer 2 (SO-2) type power purchase agreement to Southern California Edison
Operational Dispatch: Solar operation during sunny hours. Natural gas backup operated to augment solar during summer peak from 12 p.m. to 6 p.m. as necessary and during mid-peak hours.
Special Incentives: Federal investment tax credits, solar property tax exclusion, accelerated depreciation
Status: Daily operation

SEGS VII
Location: Mojave Desert, Kramer Junction, California
First Year of Operation: 1989
Type: Solar electric generating station (SEGS); solar steam generation and solar superheating; auxiliary natural gas boiler to provide backup capability during low and non-solar hours.
Fossil fuel: Natural gas
Net Output: 30 MW
Principals: FPL Energy (Owner/Operator), Luz (Developer), Southern California Edison (Utility PPA)
Solar Technology: Luz LS-2 and LS-3 collectors
Project Type: Public Utility Regulatory Policies Act (PURPA) Qualifying Facility IPP with Standard Offer 4 (SO-4) type power purchase agreement to Southern California Edison
Operational Dispatch: Solar operation during sunny hours. Natural gas backup operated to augment solar during summer peak from 12 p.m. to 6 p.m. as necessary and during mid-peak hours.
Special Incentives: Federal and state investment tax credits, solar property tax exclusion, accelerated depreciation.
Status: Daily operation

SEGS VI
Location: Mojave Desert, Kramer Junction, California
First Year of Operation: 1989
Type: Solar electric generating station (SEGS); solar steam generation and solar superheating; auxiliary natural gas boiler to provide backup capability during low and non-solar hours.
Fossil fuel: Natural gas
Net Output: 30 MW
Principals: FPL Energy (owner/operator), Luz (developer), Southern California Edison (utility PPA)
Solar Technology: Luz LS-2 collectors
Project Type: Public Utility Regulatory Policies Act (PURPA) Qualifying Facility IPP with Standard Offer 4 (SO-4) type power purchase agreement to Southern California Edison
Operational Dispatch: Solar operation during sunny hours. Natural gas backup operated to augment solar during summer peak from 12 p.m. to 6 p.m. as necessary and during mid-peak hours.
Special Incentives: Federal and state investment tax credits, solar property tax exclusion, accelerated depreciation.
Status: Daily operation

SEGS V
Location: Mojave Desert, Kramer Junction, California
First Year of Operation: 1988
Type: Solar electric generating station (SEGS); solar steam generation and solar superheating; auxiliary natural gas boiler to provide backup capability during low and non-solar hours
Fossil fuel: Natural gas
Net Output: 30 MW
Principals: FPL Energy (owner/operator), Luz (developer), Southern California Edison (utility PPA)
Solar Technology: Luz LS-2 collectors
Project Type: Public Utility Regulatory Policies Act (PURPA) Qualifying Facility IPP with Standard Offer 4 (SO-4) type power purchase agreement to Southern California Edison
Operational Dispatch: Solar operation during sunny hours. Natural gas backup operated to augment solar during summer peak from 12 p.m. to 6 p.m. as necessary and during mid-peak hours.
Special Incentives: Federal and state investment tax credits, solar property tax exclusion, accelerated depreciation.
Status: Daily operation

SEGS IV
Location: Mojave Desert, Kramer Junction, California
First Year of Operation: 1987
Type: Solar electric generating station (SEGS); solar steam generation and solar superheating; auxiliary natural gas boiler to provide backup capability during low and non-solar hours
Fossil fuel: Natural gas
Net Output: 30 MW
Principals: FPL Energy (owner/operator), Luz (developer), Southern California Edison (utility PPA)
Solar Technology: Luz LS-2 collectors
Project Type: Public Utility Regulatory Policies Act (PURPA) Qualifying Facility IPP with Standard Offer 4 (SO-4) type power purchase agreement to Southern California Edison
Operational Dispatch: Solar operation during sunny hours. Natural gas backup operated to augment solar during summer peak from 12 p.m. to 6 p.m. as necessary and during mid-peak hours.
Special Incentives: Federal and state investment tax credits, solar property tax exclusion, accelerated depreciation.
Status: Daily operation

SEGS III
Location: Mojave Desert, Kramer Junction, California
First Year of Operation: 1987
Type: Solar electric generating station (SEGS); solar steam generation and solar superheating; auxiliary natural gas boiler to provide backup capability during low and non-solar hours.
Fossil fuel: Natural gas
Net Output: 30 MW
Principals: FPL Energy (owner/operator), Luz (developer), Southern California Edison (utility PPA)
Solar Technology: Luz LS-2 collectors
Project Type: Public Utility Regulatory Policies Act (PURPA) Qualifying Facility IPP with Standard Offer 4 (SO-4) type power purchase agreement to Southern California Edison
Operational Dispatch: Solar operation during sunny hours. Natural gas backup operated to augment solar during summer peak from 12 p.m. to 6 p.m. as necessary and during mid-peak hours.
Special Incentives: Federal and state investment tax credits, solar property tax exclusion, accelerated depreciation.
Status: Daily operation

SEGS II
Location: Mojave Desert, Daggett, California
First Year of Operation: 1986
Type: Solar electric generating station (SEGS); solar steam generation and solar superheating; auxiliary natural gas boiler to provide backup capability during low and non-solar hours.
Fossil fuel: Natural gas
Net Output: 30 MW
Principals: Sunray Energy, Inc. (owner/operator), Luz (developer), Southern California Edison (utility PPA)
Solar Technology: Luz LS-1 and LS-2 collectors
Project Type: Public Utility Regulatory Policies Act (PURPA) Qualifying Facility IPP with special Standard Offer 2 (SO-2) type power purchase agreement to Southern California Edison
Operational Dispatch: Solar operation during sunny hours. Natural gas backup operated to augment solar during summer peak from 12 p.m. to 6 p.m. as necessary.
Special Incentives: Federal and state investment tax credits, solar property tax exclusion, accelerated depreciation.
Status: Daily operation

SEGS I
Location: Mojave Desert, Daggett, California
First Year of Operation: 1985
Type: Solar electric generating station (SEGS); solar steam generation with natural gas superheating, including three hours of thermal energy storage.
Fossil fuel: Natural gas
Net Output: 13.8 MW
Principals: Sunray Energy, Inc. (owner/operator), Luz (developer), Southern California Edison (utility PPA)
Solar Technology: Luz LS-1 and LS-2 collectors
Project Type: Public Utility Regulatory Policies Act (PURPA) Qualifying Facility IPP with special Standard Offer 2 (SO-2) type power purchase agreement to Southern California Edison
Operational Dispatch: Solar operation during sunny hours. The plant initially had 3 hours of thermal energy storage that was used to dispatch to peak period. The storage system was damaged by fire in 1999 and was not replaced.
Special Incentives: Federal and state investment tax credits, solar property tax exclusion, accelerated depreciation.
Status: Daily operation

Sources:

 

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