Concentrating Solar Power Technologies
Dr. Raed Sherif V.P., International Markets eSolar, Inc. raed.sherif@esolar.com
Presented at the iNEMI Alternative Energy Workshop San Jose, California ‐ October 20‐21, 2010 Overview of Solar Technologies Platforms
Solar Technologies
Photovoltaic Solar Thermal
Silicon Thin Film Concentrated Parabolic Linear Power Sterling Panels Panels PV Panels Trough Fresnel Tower Engine
Non‐concentrating Concentrating
2 Technology Efficiency Status Markets Pros Cons
Si panels 14% - 22% DC Standard, mature (GW Primarily Diffuse sun, Intermittent, no deployment), 75% rooftops and established, clear path for market share commercial , proven cost higher efficiency , and lately utility reduction path higher investment to set up manufacturing Thin films ~ 11% DC CdTe of FS 25% market Utilities Diffuse sun, lowest Material set, low share, other thin film capital cost efficiency, high about ready to enter the BOS costs market CPV 25% - 32% DC Fragmented, emerging, Commercial, Very high Few many technologies, less utilities efficiency demonstrations, than 20 MW installed potential, low use use of DNI only of semiconductor, lower manufacturing set up costs CSP-Trough 14-15% AC Mature, standard, over Utility power Established, over Water use, use of 650 MW installed and generation 20 + years, can be DNI only, low many PPA’s including hybridized, potential for cost storage storage capability reduction CSP- CLFR 11% AC Under 10 MW installed, Industrial steam, Low capital cost, Water use, use of but finalist in the Solar utility power steam suitable for DNI only, low Flagship of Australia generation industrial process efficiency, low heat steam temperature
CSP- Tower 18% - 22% AC Different solar fields, Utility power High efficiency, Water use, use of under 40 MW installed, generation path for low DNI only PPA’s signed for LCOE, storage, hundreds of MW hybrid Concentrating Photovoltaic
History
CPV Module Components
The Promise of CPV
Status of the Technology
Opportunities & Challenges History
Go back to 1980 and ask: why is solar expensive?
To a first degree, the semiconductor is expensive And it is inefficient (low kWh produced for every kW installed) So you need a lot of semiconductor area
Two solutions were considered
¾ Reduce cost of semiconductor
¾ Use Concentration Some Historical CPV Systems
Interest in CPV evident in the 1970’s and 1980’s systems
But back then, CPV was too expensive –the technology was not ready!
6 Meanwhile, PV found a niche application
100 Historical
1980 $21.83/W Projected 2004! 1985
$2002) $11.20/W 1990
$6.07/W 1995 10 $4.90/ W 2000 $3.89/W 2005 $2.70/W 2010 $1.82/W 2013 Module Price ($/W) ( ($/W) Price Module $1.44/W
1 1 10 100 1000 10000 100000 Cumulative Production (MW)
PV was cost efficient in remote applications, then through FIT and incentive programs, gained market in grid‐connected
Projections of lower module cost with higher volumes, increased efficiency, and automation have come true –except the time of silicon shortage A New, Disruptive Technology
High efficiency, super expensive “multi‐junction” solar cells made their way into the domain of solar energy because of space application, building on the “dual‐junction” technology that was developed by the DOE
Picture courtesy of Spectrolab
High‐efficiency solar cells made of III‐V materials used to power spacecrafts Multijunction PV Sunlight
TOP CELL Contact 1.0 A/R* A/R*
Top Cell: GaInP 0.8 2 MIDDLE CELL Tunnel Junction 0.6 Middle Cell: GaInAs 0.4 BOTTOM CELL Tunnel Junction 0.2 Drawing Not To Scale To Drawing Not INTENSITY (ARB UNITS) (ARB INTENSITY Bottom Cell: Ge GaInP2 GaInAs Ge 0 0.25 0.45 0.65 0.85 1.05 1.25 1.45 1.65 1.85 Ge Substrate WAVELENGTH (Microns) Contact Picture courtesy of Spectrolab *A/R: Anti-Reflective Coating
• State of the art is the 3J cell • Typical 3J cell contains 20 layers or more • Divides the solar spectrum (l < 1.750 mm) to maximize efficiency CPV Module Components
• Primary optics collect the DNI light • Secondary optics homogenize the light and focus more on the PV cell • High efficiency cell package to receive concentrated light • A system of heat removal and electric connections • Dual‐axis tracking
Example of a CPV module‐ picture courtesy of Amonix Concentrating Photovoltaic Receivers/Cell Assemblies
Solar Cell
Receiver
Sub-Module Module (total of 50 modules mounted on a dual-axis tracker) CPV Receiver/Cell Assembly ‐ Electric connection Example of a CPV module‐ picture courtesy of Sol3G ‐ Heat dissipation ‐ Reliability ‐ Cost The promise of CPV‐ Path to Lowest LCOE
• Efficiency is leveraging in reducing LCOE • Cell utilization is very small (1/1000 of the silicon cells) • Cells replaced with conventional materials (steel, aluminum, glass) • Promises of higher efficiency and lower cell costs have been coming true • Field demonstrations and IEC qualification testing show technology to be robust • Industry is nowhere near taking advantage of economies of scale yet CPV Advantage in Performance • Dual‐axis tracking provides higher kWh/kWp, and higher capacity factor‐ almost 60% higher than stationary flat plate Si module 100 1 90 111 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 80 1 1 JJ J 1 J JJ J J J J J J J J J J J J J 1 1 70 HH H J J H H H H H H H 60 H H 1 H H 50 J H H H J H 40 H H J J H H 30 1 Amonix = 8.8 kWh/kW H 20 H J Single axis = 7.2 kWh/kW H H J 10 JH H Fixed Flat Plate = 5.0 kWh/kW H JH J 0 JJJ 1111 JHHHH 1 6 8 10 12 14 16 18 Local time (h) Picture courtesy of Amonix
• For a 1 MW plant, CPV system would produce >8 GWh over a 25 year life more than a thin film panel CPV Chip Efficiency vs. Other Technologies
• CPV chips efficiency increase about 1% per year: 40% commercial by end of 2010 , 42‐43% by 2012 and path for > 45%, while prices going down due to economies of scale, automation, and learning
Picture courtesy of NREL Where the CPV Industry is now, and where it is heading
Parameter Status in 2007 Status in 2010 Projected by 2015
$/W installed $7‐$10/W $4‐$6/W <$3/W
Cents/kWh >$30 cents/kWh $15‐$20 cents/kWh Under $10 cents/kWh
Research device 40.7% 41.6% (recently 42.3%) 48% eff.
Commercial 35‐37% 39‐40% 42‐43% device eff.
Commercial cell $10‐$15/sq. cm $6‐$8/sq. cm $3‐$5/sq. cm cost
Demonstrations Under 1 MW 4‐6MW with PPA’s Hundreds of MW signed for 30+ MW
Source: Dr. Sarah Kurtz of NREL Report on CPV Opportunities & Challenges
• Technology has the potential to reach low LCOE • Promises of commercial chip efficiencies of 40% and above are happening‐ chip efficiencies of 50% and above are doable! • Many new chip suppliers, ensuring continuous drive to increase efficiency, reduce cost, and meet volume demands • IEC qualification standards established, and CPV modules are meeting the standards • Field demonstrations are proving viability of the technology • PPA’s are being signed
• No economies of scale achieved yet • Bankability issues • Fragmented technology, no standardization Concentrating Solar Power Tower
Why Tower?
Traditional Obstacles to CSP
Innovations in CSP Tower
Opportunities & Challenges Among CSP technologies, the CSP Tower offers the best opportunities for scalable solar power at the lowest cost
Trough Linear Fresnel Reflectors Tower
Most mature Tubes fixed in place Dual axis tracking technology (over 500 Use direct steam High concentration MW installed) Low concentration High maximum Single axis tracking Low maximum temperature Synthetic oil temperature Demonstrated in Solar Costly heat Lowest efficiency (~ 11%) One, Solar Two, PS‐10, PS‐ exchangers Limited demonstration 20, Sierra Low concentration Highest efficiency (18‐ Medium efficiency (~ 22%) 16%) Question:
Why is CSP expensive? Materials, construction and installation have been costly for CSP
Traditional CSP requires intensive field construction –cranes, power tools, and heavy civil work with expensive foundations Mirrors use up large amounts of steel and concrete to resist wind loads Precision installation, calibration, and alignment are time consuming
Source: Abengoa PS‐10 project Lifting of a trough during construction Conventional technology
Curved trough mirrors and large heliostats (120 m2) require heavy support structures and expensive manual labor
Trough mirror assembly Other power tower The actuator is large and on site with large steel heliostats require 3’ heavily engineered support structures diameter steel posts set 20’ into the ground eSolar: Innovative Modular and Scalable CSP
Thermal Receiver [direct steam generation]
Receiver Tower South field of tracking mirrors
North field of tracking mirrors
Award‐winning Technology 2010 World Economic Forum Technology Pioneer Award 2010 Renewable Energy World’s “Renewable Project of the Year” 2009 Power Engineering “Best Renewable Project of the Year” Commercial Demonstration: Sierra SunTower Project
Each module produces 2.5‐2.8 MW All solar field components have been demonstrated at commercial scale 46 MW units fit on a 250 acre land (~ 1 square km) Can be deployed in 18‐22 months
The Sierra SunTower produces 5 MW and consists of 2 modules side‐by‐side in Lancaster, California. Each module has 12,000 tracking mirrors focusing light on a receiver atop a 60 meter tower.
Concept of a power plant using 12 modules side‐by‐side feeding one steam turbine to form a 46 MW power plant. Close‐up view of the mirror field. Notice the fact that there is no ground penetration. Frames come pre‐wired from the factory. Pre‐Fabricated Components for Easy & Rapid Construction
Pre‐fabricated mirrors and frames arrive Simple, linear design and field layout in standard shipping containers on site reduce high ground preparation costs
Standard 210’ (65 m) wind towers are External boiler designed by repurposed to host receivers, expediting the Babcock & Wilcox permitting process Big savings in Construction Costs! Solar Trough/ eSolar System Other CSP Towers
Expensive crews, cranes and Only hand tools (one ratchet power tools required, with wrench) required to unfold and excavating, welding and tighten entire solar field in place fabrication done on‐site with NO ground penetration Cost Reduction and Local Manufacturing Opportunities Small, flat mirrors require less steel, and can be manufactured locally Low profile installation reduces construction equipment and labor cost Pre‐fabricated components requiring less skilled labor for assembly on site Small, flat mirrors ~1 sq. meters ensure lower material and labor costs
Mirror field is installed using hand tools with no ground penetration eSolar’s Core Innovation: Automated Calibration & Tracking System Two‐axis tracking is supported by cameras and proprietary software
System of cameras
Fully‐automated
Heliostat availability > 99.9%
Full calibration in < 20 days
Automated solar field calibration
Before calibration After calibration Individually Controlled Mirror Field eSolar Automatic Heliostat Cleaning Robot
Cleaning position where the rows of mirrors face each other and an eSolar proprietary cleaning robot move between rows Sierra SunTower
All information contained in this presentation is confidential. No reproduction or distribution of this material is permitted without prior authorization from eSolar. First Commercial Demonstration Over 24,000 mirrors, 2 towers, one power block
Break ground July 2008, supply electricity to grid August 2009 Sierra SunTower – Time Line
Only operating solar tower power plant in the U.S. and one of only three in the world
Validates eSolar’s technology; 3rd party engineer’s studies complete
Operational history matched or exceeded company forecasts
Small form factor enabled siting of power plant close to load
12‐month construction period
Sierra SunTower Continues to provide invaluable data to further improve future power plants
June Construction December April July August begins Heliostats installed First Sun First Sync Unveiling 2008 2009 2010
All information contained in this presentation is confidential. 3 No reproduction or distribution of this material is permitted without prior authorization from eSolar. Official Opening August 5, 2009 Sierra SunTower: Summary of Daily Performance
eSolar’s calibration system has allowed it to precisely predict receiver thermal energy absorption Predictive ability has consistently improved throughout Sierra SunTower’s operational life Energy absorption model is transferable globally to large scale power plants
All information contained in this presentation is confidential. 3 No reproduction or distribution of this material is permitted without prior authorization from eSolar. Thought
“If you want to find a new idea, read an old book!” Bobby Fischer