concentrating solar power: the emerging solar energy technology
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Concentrating Solar Power: The Emerging Solar Energy Technology
Presentation to
Electric Power 2010Session 4B:
Solar Power and Photovoltaic
Dr. Allan R. HoffmanU.S. Department of Energy
19 May 2010
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Outline of Presentation
Why the renewed interest?
The four “flavors” of concentrating solar power (CSP)
CSP history
Advantages and disadvantages
Thermal storage
Current status
Concluding remarks
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Why the Renewed Interest in CSP? traditional CSP (trough, tower, dish) is not new – long history
dating back to 1980’s
key advantage: close resemblance to existing plants use many of the same technologies and equipment substitutes concentrated high-temperature solar heat for combustion of fossil fuels or heat from nuclear reactors
Increasing utility interest in deployment of CSP plants to meet requirements of state renewable portfolio standards
huge solar resource in Southwest U.S.
federal government encouraging development of CSP plants through 30% investment tax credit
good through FY 2016 alternative 30% Treasury grant good through FY 2010
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State Renewable Portfolio Standards
http://www.epa.gov/chp/state-policy/renewable_fs.html
States with RPS States with RPS goal
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Four CSP technologies CSP technology systems use reflective surfaces to gather
and concentrate unscattered solar radiation to create heat
The requirement for unscattered (“direct normal”) radiation limits CSP plants to certain locations, primarily desert regions with limited cloud cover
Three of the four CSP technologies use the collected heat to power conventional Rankine steam cycles, similar to those used for coal and nuclear plants parabolic trough, linear Fresnel, power tower
Dish-engine systems use the concentrated sunlight to power a small heat engine at the dish’s focal point
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Parabolic Trough
Kramer Junction, CA
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Power Tower
Barstow, CA
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Dish-Engine
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Compact Linear Fresnel
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CSP History - Luz and SEGS nine trough systems, SEGS I-IX, built by Luz International between
1984 and 1990 (354 MWe total) SEGS I: 13.8MWe SEGS II-VII: 30MWe each SEGS VIII, IX: 80 MWe each
regulatory and policy obstacles forced Luz bankruptcy in 1991 plans to construct SEGS X, XI and XII canceled (240 MWe)
nine original SEGS plants still operating, feeding power into Southern CA Edison power grid (but under new ownership)
largest solar power station complex in operation
original Luz owner now head of Bright Source Energy Inc. Luz II technology uses distributed power towers (DPT)
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Advantages resemble traditional power plants
generation based on steam and is large scale use standard equipment for power generation
can be built in small sizes and added to as needed can achieve high steam operating temperatures, allowing more efficient power generation capable of combined heat and power generation
steam for absorption chillers, industrial process heat, desalination
Non-carbon emitting power generation incorporates storage
storage not major part of generation cost size of steam power plant that lacks storage does not have
to be increased when storage added added storage cost effective if energy sold at peak hours allows generation to match utility load profile can be hybridized with intermittent renewables
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Disadvantages
high upfront capital costs for concentrators and storage
require unscattered “direct normal” solar radiation, thus limiting where CSP plants can be located
desert areas are best (but also arid)
require cooling, as with any steam power plant, creating a requirement for water or air cooling
water limitations may necessitate air cooling in many locations, with penalty in capital cost, generating efficiency and energy cost
require large surface areas for placement of concentrators
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Thermal Storage
SEGS-I storage method used an organic heat transfer fluid (HTF) organic HTFs can only be used below 800F troughs can operate at just over 1000F, thus use of HTF limits plant efficiency by >12%
power towers can reach very high temperatures (>2000F) but have only been used to date with molten salt storage Salt melts at 430F (must be kept heated) maximum storage temperature: 950F
Modern trough plants: either use no storage
more profitable under current U.S. incentives to build without storage, or
use HTF and molten salt storage
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Can We Do Better? Modern high efficiency power plants can be designed to use steam at 1300-1400F
ideal storage temperature: 1500-1700F
desired top temperature for gas turbines is > 1700F
a heat transfer fluid and storage method that operate at temperatures above those of HTFs and molten salt would lead to significant energy cost reductions (>30%)
Such a heat transfer and storage system has been invented by Dr. Reuel Shinnar (City University of New York)
(patent # 20090178409/Apparatus and Method for Storing Heat Energy, 16 July 2009)
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The Shinnar Thermal Storage System combines two proven concepts with a special adaptation
uses pressurized CO2 as the heat transfer fluid flowing in a closed loop through the solar collectors and either through the power plant or the heat storage system
compressed CO2 is one of the most effective gaseous high temperature heat transfer fluids used in industry
The heat storage system uses commercially available vessels (cylindrical metal pipe) filled with a ceramic solid filler
can be designed to operate at temperatures up to 3000F
special feature: uses a cyclic counter-current pebble bed pebble-bed heat exhanger based on theory developed in 1920s has been used reliably for many industrial processes heat propagates as a sharp front: one end of storage remains cold, the
other end hot at constant temperature allows recovery of heat at same top temperature it was stored
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Current Status after a long hiatus, deployed CSP capacity has expanded from 354 MWe to
more than 820 MWe today many new projects are in the pipeline in many countries
when those under construction are completed, capacity will approach 3,000 MWe
an even greater number of projects are in development > 10,000MWe in the U.S. alone
CSP plants deployed or under development in USA Spain Italy Morocco Algeria Egypt Jordan Tunisia
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SolarPACES (Solar Power And Chemical
Energy Systems) collaborative RD&D program (Implementing Agreement) under
umbrella of International Energy Agency that focuses on development and marketing of CSP systems
Currently has 16 member countries Australia, Austria, Algeria, Egypt, EC, France, Germany, Israel,
Italy, Mexico, S. Korea, S. Africa, Spain, Switzerland, UAE, USA membership open to all countries
compiles data on CSP projects around the world that have plants that are operational, under construction, or under development can browse project files by country, project name, technology
and status http://www.solarpaces.org/News/Projects/projects.htm
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CSP Projects in the U.S. California
Abengoa Mojave Solar Project Alpine Sun Tower Blythe Solar Power Project Calico-Solar one Genesis Solar Energy Project Imperial Valley-Solar Two Ivanpah Solar Electric Generating Station Kimberlina Solar Electric Generating Station Palen Solar Power Project Rice Solar Energy Project Ridgecrest Solar Power Project Sierra SunTower SEGS I-IX
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CSP Projects in the U.S. (continued)
Nevada Crescent Dunes Solar Electric Project (Tonopah) Nevada Solar One (NSO)
Arizona Maricopa Solar Project Saquaro Power Plant Solana
Florida Martin Next Generation Solar Energy Center MNGSEC)
New Mexico New Mexico SunTower
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DESERTEC Derives from the TREC concept which has been around for
many years: generate CSP electricity in N. Africa, ship electricity to Europe, use revenues to stimulate African development
DESERTEC Foundation created in 2008 to advance DESERTEC Concept worldwide
DESERTEC Industrial Initiative (DII) established in 2009 under German law to create the conditions for accelerated implementation of the DESERTEC Concept in EUMENA (Europe, Middle East, North Africa) HVDC transmission to southern Europe (loss 3% per 103 km) less seasonal variation in solar insolation MENA vs. S. Europe
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Concluding Remarks
CSP has the potential to supply a significant share of U.S. and global electricity demand
ability to load follow, firm up intermittent generation, incorporate storage, and provide heat and electricity
are major advantages
cooling requirements present a water and cost challenge (as do requirements of other steam power plants)
costs still high but should come down significantly as more and more systems are manufactured and deployed
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Thank You
Contact information:
E-mail: allan.hoffman@ee.doe.gov
Telephone: 202-586-8302
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Additional Material on Shinnar TS System
“I now believe that CSP technology which follows the guidelines outlined in our report could be designed at approximately half the cost of CSP plants today despite the fact that storage and air cooling have been added.”
(letter from Dr. Shinnar to Thomas Rueckert, CSP program manager, U.S. DOE, 21 April 2010)
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