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Home , Concentrated solar power

Concentrated (CSP)

A World Solution

NATIONAL BOARD MEMBERS TECHNICAL PROGRAM October 7, 2009

Steve Torkildson, P.E. Principal Engineer Concentrated Solar Power (CSP) Clean,

Sierra 5 Mwe Lancaster, CA

PS-10 11MWe

2 Concentrated Solar Power (CSP)

• The concept: – Concentrating solar radiation creates the temperatures needed to drive a thermodynamic cycle

– Concentrating provides a endlessly renewable, low- cost and non-polluting means of generating for the entire world.

– Solar electricity production can meet the world’s demand for energy far into the future

3 Concentrated Solar Power (CSP)

• The Need: – Increasing electric power demand

• Worldwide electrical consumption will double by 2040

– Dwindling fossil reserves

– Reduction of carbon emissions

4 Current world is 15 terawatts

5 By 2050, world energy consumption is estimated to be 50 terawatts

6 • The Resource: “Our ”

– FACT • The amount of solar energy striking the earth’s surface in a single hour exceeds the amount of energy consumed worldwide in a calendar year

7 Solar provides more than 1000 times the energy required by current demands

8 • The Resource: “Our Sun”

– FACT • the amount of solar energy reaching earth yearly represents ~ 2 times the energy that can, or will be developed by all of the earth’s non-renewable resources including coal, oil, gas and uranium reserves.

Total Non-Solar Annual Solar Energy Energy Reserves 9 To generate all of the current US energy demand requires a tract of land 243 miles square

10 Solar Insolation • Solar insolation is the direct measure of solar radiation received on a surface in a defined amount of time – expressed as average irradiance in W/m2 – often expressed as ‘’ with 1 sun = 1,000 W/m2 • The average direct normal solar radiation in the earth’s upper atmosphere is ~ 1,366 W/m2 which is attenuated in the atmosphere to ~ 1,000 W/m2 – Factors influencing DNI (Direct Normal Incidence) are: » solar elevation angle (cosine effect) » cloud cover » dust & moisture 11 Daily Solar Energy Delivery

12000

10000 Summer 2 8000

6000 Winter

delivered, delivered, delivered, kW/mkW/m 4000 Q-

2000

0 6 8 10 12 14 16 18 20 Time of day

12 Solar Energy Direct Conversion - Current Approaches

Photovoltaics Thin Film PV/CPV

30¢ kWhkWh30¢ 21¢ kWh

Note: Cost figures given may not reflect current market. Producers continue to innovate and reduce costs.

13 Solar Energy Concentration Methods A variety of approaches demonstrated to date use arrays of hundreds or thousands of () to concentrate the sun’s rays to heat a transfer medium between 500oF and 1,800oF

Solar Thermal Troughs Power Tower

16¢16¢ kWhkWh16¢ kWhkWh16¢ 13¢ 13¢3¢ kWhkWh13¢ kWh1 kWh

14 CSP Solar Troughs

– long runs of parabolic Fresnel* single curvature mirrors – single axis rotation focus energy on a collector tube – oil is typical medium – ~ 400oC (750°F) oil produces in heat exchanger – conventional – solar/energy conversion efficiency ~ 15% – most notable plants are SEGS installations » Kramer Junction, CA

» 350 MWe are currently installed. – The 1st of 9 plants went into operation in 1985

* pronounced: pronounced fre’ nɛl (Wikipedia.org)

15 16 CSP Solar Troughs

– currently has a 5 MWe plant (Kimberlina) operating in Bakersfield CA – Linear Fresnel reflectors with linear flat mirrors in lieu of the parabolic mirrors (to reduce cost) and forgoing the Therminol in lieu of directly converting to high temperature steam. » Direct steam conversion offers a simpler solar integration for existing fossil facilities – Plans are being formalized to develop & build a 177 MWe plant for PG&E in Carrizo Plains, CA

17 18

Power Power Tower Overview CSP Power Towers ….  …have been demonstrated successfully at Solar One, Solar Two, and PS10  Key development barriers persist… – Expensive heliostats – Cost reduction efforts – Scale-up risk on key components – Access to transmission / permitting delays – Large project cost & risk

19 Solar PS-10

– 11MWe • saturated steam generator (495oF/580psi) • 624 mirrors >800,000ft2 • north solar field • tower @ 377 ft • Receiver eff’y @ 92% • 30 – minute storage

20 PS-20

• saturated steam generator (495oF/580psi) • large mirrors (1,291 ft2) • 1255 mirrors >1,615,000 ft2 • north solar field • tower @ 525ft • 235 acres required

21 eSolar Concept

• Small heliostats • Tracking software creates a virtual parabolic • Automatic software driven calibration of mirror position • Maximize factory assembly • Minimize field assembly • Utilize existing technologies where feasible – Conventional steam cycle – Wind turbine towers • Rapid deployment • Goal: solar plant cost = coal plant cost

22 The Problem with Solar: Economics

• Conventional Combined Cycle Power plant: – $1.00 - $1.25/watt installed cap costPS-20 + costs + volatility costs + uncertain carbon cost eSolar • Solar Thermal Industry benchmark: – Solar field ~45% of Total Plant Cost – Installation/construction ~20% “ – Receiver ~10% “ – Power Block ~15% “ • Prevailing Installed Solar Thermal Power Plants: – $3.5/watt to over $4.00 per watt installed • eSolar addresses all four major cost components to make solar thermal power cost competitive

23 Why smaller mirrors?

• Lighter • Less wind load • No concrete foundation – sits on compacted soil • Assembly without heavy equipment • Low cost production due to high volume • Rapid deployment

24 Populating the field

25 eSolar Evolution

First production unit running 16 months after test facility demonstration.

26 Starting Small eSolar Evolution

1st steam April 2nd 2008

Test Facility 27 Using computational power to create a system that is:

 Modular  Pre-fabricated  Dramatically less expensive

Unit 16 Modules Output: 46 MW

Module One tower + receiver Stick Assembly

Heliostat 28 • Multiple 46 MW Units can scale easily and quickly to any generation capacity to meet growing demand Layout flexible to accommodate land resource availability

29 eSolar has addressed traditional CSP challenges by………. Leveraging pre-fabricated, mass manufactured components  Assembled in a factory, saving high costs of field construction and civil  Flat mirrors are less expensive, faster to manufacture, and easier to deploy Focus mirrors using software, not concrete and steel  Breakthrough computer calibration and dual-axis sun-tracking control Reduce costs through a modular and scalable design  46 MW standard units, fast deployment to over 1 GW at a single site

30 • eSolar

– 5 MWe demonstration plant @ Lancaster CA – 1st sun on receiver April 18th 2009 – Key Performance criteria achieved June 20th, 2009

• Tower height @ 153’

• North & South heliostat fields @ 6,000 mirrors /field

• Heliostat @ 12 ft2

• Total mirror surface @ 144,000 ft2

• Land area @ 10 acres/ module

31 eSolar’s Steam Receiver Design Specs

• Natural circulation • Modular (shippable) configuration (minimum field assembly) • Weight limitation @ 60 tons • Tube Materials: Carbon steel & T22 • Peak heat flux @ 130,000 Btu/hr-ft2 • Average flux rates: - – Evaporator surface @ 45,000 Btu/hr-ft2 – Superheater surface @ 35,000 Btu/hr-ft2 • Extreme Cyclic Duty: - • Daily start-up and cloud transients • >20,000 lifetime startup cycles

32 Receiver prototype designs “External” Dual Cavity

Dual Cavity currently operating successfully on Tower 1 External receiver commissioning currently underway.

33 Prototype designs – Dual Cavity Receiver • Captures 97% of incident energy • Superheater surface captures ‘reflected’ radiation • Lower convection/radiation losses

•External Receiver •Surfaces mat -black for max. absorption (94%) of direct incident radiation •Higher convection/radiation losses 34 Cavity Receiver – Natural circulation • 42” steam drum, turbo separators – Membrane evaporator & pre-heater panels – ‘tangent-tube’ superheater panels

MCR Steam Conditions: 30,000 pph 900 psig 825oF Feedwater 425oF

35 5-MW Sierra Commercial Demonstration

All solar-related components being demonstrated at commercial plant sizes, mitigating scale-up risk

36 Pointing / Tracking Progress May 7th June 22nd

June 22nd The World’s largest digital display?

38 Solar Receiver Operational Challenges

• Receiver area inaccessible during operation – Risk of exposure to solar flux • Time required for daily inspections – Lock-out procedure must be followed – Time to move from tower to tower – Time to ride service lift to top of tower – Approx. ½ hour per receiver. 16 receiver plant = 8 hours • Inspection Access – Improvements needed to provide for inspection, maintenance, repairs.

39 Proposals for enhanced inspection capability

• Generous use of TV cameras to monitor critical areas and instruments • Movable access platforms • Replace daily start-up inspections with more rigorous weekly inspection

40