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)