Past, Present, and Future of Solar Thermal Generation

ABENGOA SOLARSolar Power for a Sustainable World

Past, Present, and Futureof Solar Thermal

Generation

Bruce KellyAbengoa Solar, Incorporated

Berkeley, CaliforniaJune 2008

22Solar Power for a Sustainable World

ABENGOA Topics

– Solar resource– Solar thermal technologies– Early projects– Current projects– Future plans


ABENGOA Solar Resource

Southwest US, filtered for environmental areas, urban areas, water, and slope < 3%

9,800 TWhe potential

3,800 TWhe US energy consumption


ABENGOA Parabolic Trough

• Type: Glass mirror; single axis tracking; line focus

• Nominal concentration: 80:1

• Heat collection fluid: Synthetic oil

• Peak temperature: 393 C


ABENGOA Central Receiver

Photo by Mike Taylor, SEPA

• Type: Glass mirror, two axis tracking, point focus

• Nominal concentrations: 600 to 1,200:1

• Heat collection fluids: Steam, air, or nitrate salt

• Peak temperatures: 400 to 850 C


ABENGOA Linear Fresnel

Photos taken by Mike Taylor, SEPA

• Type: Glass mirror, single axis tracking, line focus

• Nominal concentration: ~100:1

• Heat collection fluid: Saturated steam

• Peak temperature: ~260 C


ABENGOAParabolic

Trough


ABENGOAParabolic

Trough

• Early projects– Solar Electric Generating Stations (SEGS)– SEGS I and II: 14 and 30 MWe; Daggett– SEGS III through VII: 30 MWe; Kramer

Junction– SEGS VIII and IX: 80 MWe; Harper Lake

• Financed through very favorable combination of investment tax credits, Standard Offers, and PURPA requirements

• All are still in operation


ABENGOAParabolic

Trough• Current projects

– Acciona: 64 MWe Nevada Solar One– Solar Millennium: 50 MWe AndaSol 1

• Nevada Solar One financed through investment tax credit and renewable portfolio standard

• AndaSol 1 financed through Spanish feed-in tariff at ~$0.40/kWhe

• Parabolic trough technology investment to date ~$3,000 million


ABENGOAParabolic

Trough• Future plans

– Spain: 50 MWe; limited by tariff structure– US: 125 to 250 MWe; economies of scale

• Advanced collector coolants– Direct steam generation, and inorganic

nitrate salt mixtures– 450 to 500 C collector field temperatures– More efficient Rankine cycles– Why not yet? → Direct steam generation

has complex controls, and salt freezes





• Early projects– France, Spain, Italy, Japan, and United States– 1 to 10 MWe– Receiver coolants: Sodium; nitrate salt;

compressed air; and water/steam

• Design point efficiencies were close to, but annual energy efficiencies were well below, predictions

• Most suffered from lack of operating funds



• Current projects– Abengoa: PS10 and PS20– US DOE: Solar Two (1999)

• PS10 and PS20: Saturated steam receivers; high reliability, but below-commercial efficiency

• Solar Two: Nitrate salt receiver, thermal storage, and steam generator; high efficiency, but poor reliability

• Technology investment to date ~$1,000 million



• Future plans– Abengoa: Superheated steam;

compressed air; and nitrate salt– SolarReserve: Nitrate salt in South Africa

and US– eSolar: 13 distributed superheated

steam receivers; very small heliostats; central 30 MWe Rankine cycle

– BrightSource: 4 towers; small heliostats; central 100 MWe reheat Rankine cycle



• Why not yet?– Superheated steam: Moderate annual

efficiencies; thermal storage may be impractical

– Compressed air: Complex receiver; small plant sizes; thermal storage may be impractical

– Nitrate salt: Less than perfect operating experience; equipment development must occur at commercial scale, with ~$750 million project investment


ABENGOAPerformance and

Cost

• Annual efficiencies, capital costs, operation and maintenance costs, and levelized energy costs

Parabolic trough

Nitrate salt central receiver



• Annual solar-to-electric efficiencies

14 to 16 percent gross

12 to 14 percent net

• Capital cost

~$4/We without thermal storage; includes project financing, interest during construction, and owner’s costs

~$5 to $8/We with thermal storage



• Operation and maintenance cost

$0.02 to $0.04/kWhe

• Levelized energy costs

$0.14 to $18/kWhe with Southwest US direct normal radiation and 30 percent investment tax credit

$0.35 to $0.40/kWhe with southern Spain direct normal radiation and no financial incentives


ABENGOASalt Central

Receiver• Annual solar-to-electric efficiencies

17 to 19 percent gross

15 to 17 percent net

• Capital cost

~$4/We with minimum thermal storage; includes project financing, interest during construction, and owner’s costs

~$7/We with thermal storage at 70 percent annual capacity factor


ABENGOASalt Central

Receiver

• Operation and maintenance cost

$0.02 to $0.03/kWhe

• Levelized energy cost

For a commercially mature design (which does not yet exist), a nominal 20 percent below that of a parabolic trough project


ABENGOA Future Markets

• Capital investment essentially dictated by commodity prices

• Energy price parity with natural gas combined cycle plant is unlikely

• Solar thermal energy is Much better matched to utility peak

demand than wind

Immune to rapid changes in plant output common with photovoltaic projects


ABENGOA Future Markets

• With 30 percent investment tax credit and property tax exemption, solar energy prices are within $0.02 to $0.03/kWhe of market price referant

• Renewable portfolio standards, plus a modest carbon tax, should provide a commercial, multi-GWe market for solar thermal projects

Documents

Past, Present, and Future of Solar Thermal Generation