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Solar Thermal Power

John O’Donnelljod@tsugino.com

Electricity: Fuel of GDP

Where Does Electricity Come From?

Heat

Heat Makes Steam

Steam Becomes Electricity

Best efficiency at highest temperaturePrimarily limited by materials

Thermal Power Generation

½ all US potable water used here

It’s not the heat, 

• 40% of heat energy becomes electricity

• Total heat released is insignificant

It’s not the heat, it’s the CO2 

• Each molecule of CO2, during its life in the atmosphere, traps 100,000 times more heat than was released when it formed.

‐ Ken Caldeira,  Carnegie Inst.Power generation is over 40% of US and 

world CO2 emissions, and is the fastest growing sector.

100,000 times

=

Business As Usual: A Problem

We have a problem

Targets and Methods

http://tinyurl.com/hansen350

Primary Resources: Fuel Supplywaves

SOLAR

World energy use

R. Perez et al.

Wind

GasOTEC

BIO Oil

HYDRO

Uranium

COAL

Solar Thermal Power

• Now competitively priced in US

• At $30/ton CO2, economics drives deployment

• Can deliver 90% of grid power• Thousands of megawatts in contract/construction now

• Needed construction rates achievable

• US 2006 electricity: 92x92 mi

On Peak Pwr is Most Expensive(and fastest growing)

Base Load (coal, nuclear)

IntermediateCombined Cycle

Peaking GT

Solar Is Strategic and Economical

• Summer peak load growing 2x average use

• All “peak” load gas‐fired

• Electricity generation fastest growing use of natural gas

• McKinsey, CERA, Simmons predict doubling++ of US natural gas prices within 5 years

Solar Thermal Power: 1914

Solar thermal power systems

Dish                                 Tower

Trough                          Linear Fresnel

Concentrate Sunlight50-3000x concentration

Track Sun Position daily/seasonally

Store Heat Energy

Convert Heat To PowerTurbine and Stirling Engines

Economics• Collector Cost Per Area• Optical Efficiency• Thermal Losses• Engine Thermal Efficiency

Factors Driving Cost‐Efficiency

• Engine Efficiency

• Reflector Field CostPer Area

• Thermal Losses

α ε σ T4

α Receiver Areaε Emissivity

High Solar Concentration: Materials-limited, cost of precision reflectors and trackers

Lower Concentration: Reductions in reflector cost outweigh lower thermal efficiency

Solar thermal power systemsContinuous       Fresnel

Point 

Line

Dish                                 TowerStirling Energy SystemsInfiniaAbengoaSolar ReserveBrightsourceTorresol

Solar MilleniumAccionaAbengoa

Ausra

1000-3000 C 550-1000 C

350-450 C 280-380 C

Trough                          Linear Fresnel

Concept of Tower TechnologyConcept of Tower Technology

Storage

Dish EngineLink•

Trough

354 MW Solar Electric Generating Systems (SEGS)

Solar Energy Generating Systems (SEGS)

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Linear Fresnel

177 MW, 1 square mile

28Carrizo Energy Farm for PG&E in CA; rendering; Online 11/10

Solar Field Costs (Reflector + Receiver) DLR 2007 assessment of solar thermal pwr  AQUA‐CSP

Variable ε:Selective Surfaces

Solar Thermal Plant Elements

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Thermal Energy StorageChallenges

Highly specific design specifications regarding: primary HTF ‐ pressure ‐ temperature ‐ power level ‐ capacity

Storagesystem

ONE single storage technology will not meet the unique requirements of different solar power plants

Thermal Energy Storage for CSP Plants Status und Development

• Commercially available storage systems– Steam Accumulator– 2‐Tank sensible molten salt storage based on nitrate salts

• Alternative materials and concepts tested in lab and pilot scale– Solid medium sensible heat storage  ‐ concrete storage– Latent heat ‐ PCM storage– Combined storage system (concrete/PCM) for water/steam fluid– Improved molten salt storage concepts– Solid media storage for Solar Tower with Air Receiver (e.g. natural 

rocks, checker bricks, sand) • Future focus for CSP

– Higher plant efficiency => Increase process temperature– New fluids: steam, molten salt, gas/air

Steam AccumulatorsPS10

Saturated steam at 250°C50 min storage operation at 50% load

Molten Salt Storage – Andasol 1

Ø 38,5 m

14 m

292 °C 386 °C

• Storage capacity 1010 MWh (7.7h)

• Nitrate salts (60% NaNO3 + 40% KNO3)

• Salt inventory 28.500 t• Tank volume 14.000 m³• 6 HTF/salt heat exchangers

Storage: Meet Peak Demand++

Least Cost per kWh around 14 hrs storage

Optimal economics depend on tariff

California pays 2x/kWh noon-8pm M-F

Spain, others no TOD

Solar Thermal can supplyover 95% US Grid Power

Mills & Morgan, SolarPACES 2008

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Solar Thermal vs Conventional ‐ 2013

$/MWh

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Land is not (remotely) a constraint

More than 90% of world pp could be servedby clean power from deserts (DESERTEC.org) !

world electricity demand

(18,000 TWh/y)

can be produced from

300 x 300 km²

=0.23% of all deserts

distributed over “10 000” sites

Gerhard Knies, CSP 2008 Barcelona 40

US Solar Resource

100%US electricity92x92 miles

World Solar Resources

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High Voltage Direct Current (HVDC)Low‐Loss (3%/1000 km) 

CoR White Paper 2007

Sun-belt + technology belt

• synergies

• interconnection

• technology cooperation

deserts + technology

for energy, water and

climate security

Gerhard Knies, Taipei e‐parl. + WFC 2008‐03‐1/2

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Interstate Highway System

HVDC SuperhighwaysInterchanges to today's hubsStability, Cost, Job Growth, Energy + Climate Security

Can this be done?Give us 100% Clean Electricitywithin 10 years.

• 800 GW by 2017

• 80 GW/yr build!

• Resource availability 

• Readiness of technology

• Transmission corridors

• Cost of power

• Reliability of supply

US Power Generation 50 yr History

www.eia.doe.gov

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Market forces  caused 70 GW/yr buildout

China building >100 GW/yr

Can we build 80 GW/yr?    Yes         Can

48http://tinyurl.com/perez-v-08