why concentrating solar power?
TRANSCRIPT
CONCENTRATING SOLAR POWER NOWCLEAN ENERGY FOR SUSTAINABLE DEVELOPMENT
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➔ SOLAR ENERGY DRIVES CONVENTIONAL POWER PLANTS Concentrating solar collectors produce high temperature heat to operate steam and gas turbines, combinedcycles or stand alone engines for electricity or for combined heat and power.
➔ DAY AND NIGHT POWER SUPPLY Thermal storage systems allow for night-time solar power generation. Fuels like oil, gas, coal or biomass canadditionally be used to deliver electricity whenever required.
➔ LOW COST SOLAR ELECTRICITY Concentrating solar power still requires support, but co-firing and special schemes of finance yield affordable power already today.
➔ SOLUTIONS FOR POWER AND WATER Process heat from combined generation can be used for seawater desalination, thus helping to reduce thethreat of freshwater scarcity in many arid countries.
➔ LARGE POTENTIAL FOR SUSTAINABLE DEVELOPMENT The concentrating solar power potential exceeds the world electricity demand by more than 100 times.
Published by: The Federal Ministry for the Environment, Nature Conservation and Nuclear Safety (BMU)Public Relations DivisionD-11055 Berlin, GermanyE-Mail: [email protected]: http://www.bmu.de
Editorial Work: Dr. Franz Trieb, German Aerospace Center (DLR), Institute of Technical Thermodynamics, StuttgartDr. Wolfhart Dürrschmidt, Ludger Lorych, BMU Division Z II 7, Berlin
Design: Block Design, Berlin
Photo credits: German Aerospace Center (pages 1, 3, 6, 7)Schlaich, Bergermann und Partner, Stuttgart (page 7)Kramer Junction Company (page 6)
First print run: 5,000
Print date: July 2002
This brochure was created within the programme “Future Investments” (ZIP) in cooperation of BMU and DLR. To obtain an extendedversion by December 2002, please contact the BMU website http://www.bmu.de (use the “search” facility for “concentrating solarpower”) or write to BMU.
How can the sun drive a powerplant?
In a simple way: the solar radiation can be collectedby different Concentrating Solar Power (CSP) techno-logies to provide high temperature heat (bottom).The solar heat is then used to operate a conventio-nal power cycle, such as a steam or gas turbine, ora Stirling engine.
Solar heat collected during daytime can be storedin concrete, molten salt, ceramics or phase-changemedia. At night, it can be extracted from the stora-ge to run the power block.
Combined generation of heat and power by CSP isparticularly interesting, as the high value solar in-put energy is used with the best possible efficiency,exceeding 85 %. Process heat from combined ge-neration can be used for industrial applications, dis-trict cooling or sea water desalination. CSP is one ofthe best suited technologies to help, in an afforda-ble way, mitigate climate change as well as to redu-ce the consumption of fossil fuels. Therefore, CSPhas a large potential to contribute to the sustaina-ble generation of power.
Parabolic Trough Power Plants (right) as well asSolar Power Towers and Parabolic Dish Engines(page 7) are the current CSP technologies. Parabolictrough plants with 354 MW of presently installedcapacity have been in commercial operation formany years. Power Towers and Dish Engines havebeen tested successfully in a series of demonstrationprojects.
PRINCIPLES OF CONCENTRATING SOLAR POWER
Principle of a concentrating solar power system forelectricity generation or for the combined generationof heat and power.
Concentrating Solar Collector Field
Thermal EnergyStorage (optional)
Power Block ElectricityProcess Heat
Fuel
Sola
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WHY CONCENTRATING SOLAR POWER?
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L e v e l i s e d E l e c t r i c i t y C o s t ( c t / k W h )
Life cycle CO2-emissions of different power technologies: This life cycle assessment of CO2-emissions is based on the present energy mix of Germany. CSP value is valid for an 80 MW parabolic trough steam cycle in solar only operation mode. PV and CSP in North Africa. CC: Combined Cycle.
C O 2 - E q u i v a l e n t ( k g / M W h )
S o u r c e : S o l a r P a c e s
Coal / Steam Natural Gas / CC Photovoltaics Wind Power Hydro-Power CSP (Trough)
Economic Sustainability
The history of the Solar Electricity GeneratingSystems (SEGS) in California shows impressive costreductions achieved up to now, with electricity costsranging today between 10 and 15 ct/kWh. However,most of the learning curve is still ahead (top). Ad-vanced technologies, mass production, economies ofscale and improved operation will allow to reducethe solar electricity cost to a competitive level wit-hin the next 10 to 15 years. This will reduce the
dependency on fossil fuels and thus, the risk of fu-ture electricity cost escalation. Hybrid solar-and-fuelplants, at favourable sites, making use of specialschemes of finance, can already deliver competitive-ly priced electricity today.
Environmental Sustainability
Life cycle assessment of emissions (bottom) and ofland surface impacts of the concentrating solarpower systems shows that they are best suited for
S o u r c e : D L R
Initial SEGS plants
Larger SEGS plants
O&M cost reduction of SEGS plants
Advanced Concentrating Solar Power
Added value for green pricing
Conventional cost of peak or intermediate power
Cost perspectives of CSP until 2020.
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the reduction of greenhouse gases and other pol-lutants, without creating other environmental risksor contamination. For example, each square meterof collector surface can avoid 250 to 400 kg of CO2-emissions per year. The energy payback time of theconcentrating solar power systems is in the order ofonly 5 months. This compares very favourably withtheir life span of approximately 25 to 30 years. Mostof the collector materials can be recycled and usedagain for further plants.
Social Sustainability
CSP systems supply electricity and process heat likeany conventional power plant (top). Their integrati-on into the grid does not require any measures forstabilisation or backup capacity. On the contrary,they can be used for these purposes, allowing for a smooth transition from today’s fossil fuel basedpower schemes to a future renewable energy eco-nomy. Large electricity grids such as a Euro-Medi-terranean Power Pool via High Voltage Direct Cur-rent Transmission will in the medium term allowfor an intercontinental transport of renewable elec-tricity. The existing power line from Spain to Mo-rocco could already be used for this purpose. Thisconcept will help to stabilise the political and eco-nomic relations between the countries of the Northand the South (right).
In sunbelt countries, CSP will reduce the consumpti-on of fossil energy resources and the need for ener-gy imports. The power supply will be diversifiedwith a resource that is distributed in a fair way and
accessible by many countries. Process heat fromcombined generation can be used for seawater de-salination and help, together with a more rationaluse of water, to address the challenge of growingwater scarcity in many arid regions. Thus, CSP willnot only create thousands of jobs and boost econo-my, but will also effectively reduce the risks of con-flicts related to energy, water and climate change.
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Sketch of a parabolic trough steam cycle plant.
Vision of a Euro-Mediterranean grid interconnecting sites with large renewable electricity resources.
Solar Trough Field
Storage
Field Pump
Reheater
Super Heater
SteamGenerator
Preheater Condensate Pump
Turbine Generator
Condenser
FossilBackup
Solar Wind
EURO-MED
Hydro Geothermal
possible further interconnections
S o u r c e : I S E T
Parabolic Trough Systems
Steam cycle power plants with up to 80 MW capaci-ty using parabolic trough collectors have been incommercial operation for more than fifteen years.Nine plants with a total of 354 MW of installedpower are feeding the Californian electric grid with800 million kWh/year at a cost of about 10 to12 ct/kWh. The plants have proven a maximum ef-ficiency of 21 % for the conversion of direct solarradiation into grid electricity (top and bottom left).
A European consortium has developed the nextcollector generation, the EUROTROUGH, which aimsto achieve better performance and cost by enhan-cing the trough structure. The new collector will betested in 2003 under real operating conditions inthe Californian solar thermal power plants withinthe PARASOL project funded by the German FederalMinistry for the Environment. While the plants in
California use a synthetic oil as heat transfer fluidin the collectors, efforts to achieve direct steamgeneration within the absorber tubes are under wayin the projects DISS and INDITEP sponsored by theEuropean Commission, in order to reduce the costsfurther (top right).
Another option under investigation is the approxi-mation of the parabolic troughs by segmented mir-rors according to the principle of Fresnel. Althoughthis will reduce the efficiency, it shows a considera-ble potential for cost reduction. The close arrange-ment of the mirrors requires less land and providesa partially shaded, useful space below (bottomright).
Solar Tower Systems
Concentrating the sunlight by up to 600 times, solartowers are capable of heating air or other media to
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CSP TECHNOLOGIES – THE STATE OF THE ART
Receiver
Parabolic TroughReflector
Sunlight
Fresnel Reflector
Secondary Reflector
Absorber Tube
Sunlight
Receiver: Oil or Steamat 390 to 550 °C100 to 120 bar *
Receiver: Steam at 270 to 550 °C25 to 120 bar *
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1200 °C and higher. The hot air may be used forsteam generation or – making use of the full poten-tial of this high-temperature technology in the futu-re – to drive gas turbines. The PS10 project in San-lucar, Spain, aims to build a first European steamcycle pilot plant with 10 MW of power.
For gas turbine operation, the air to be heated mustpass through a pressurised solar receiver with asolar window. Combined cycle power plants usingthis method will require 30 % less collector areathan equivalent steam cycles. At present, a first pro-totype to demonstrate this concept is built withinthe European SOLGATE project with three receiverunits coupled to a 250 kW gas turbine (top and bot-tom left).
Parabolic Dish Engines
Parabolic dish concentrators are relatively smallunits that have a motor-generator in the focal pointof the reflector. The motor-generator unit may bebased on a Stirling engine or a small gas turbine.
Their size typically ranges from 5 to 15 m of dia-meter or 5 to 25 kW of power, respectively. Like allconcentrating systems, they can additionally bepowered by fossil fuel or biomass, providing firmcapacity at any time. Because of their size, they areparticularly well suited for decentralised power sup-ply and remote, stand-alone power systems.
Within the European project EURODISH, a costeffective 10 kW Dish-Stirling engine for decentrali-sed electric power generation is being developed bya European consortium with partners from industryand research (top and bottom right).
http://www.kjcsolar.comhttp://www.flabeg.dehttp://www.solarmillenium.dehttp://www.eurotrough.comhttp://www.solarmundo.behttp://www.sbp.dehttp://www.dlr.de/TT/solartherm/solargasturbinehttp://www.klst.com/projekte/eurodish
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Receiver
Receiver
HeliostatReflectors
Parabolic Dish ReflectorSunlight
Sunlight
Receiver: Air at 600 to 1200 °C 1 to 20 bar *
Receiver: Air or Helium at 600 to 1200 °C 50 to 200 bar *
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Step 1: Basic Project Information
The initial step of a CSP project is to identify thebasic investment opportunities. First evaluation canbe started e.g. by regional authorities with eventualsupport from CSP experts to assess general informa-tion on the market chances, capacity requirement,cost level, revenues, availability of finance, nationalpolicies, the level of political risks, the solar irradia-tion level, possible project implementation structu-res and the general availability of sites. If the out-come is promising, partners for a project companyand sources of finance for project developmentmust be agreed.
Step 2: Project Assessment
A pre-feasibility study will include solar energy re-source assessment, a preliminary conceptual designof the plant and technical and economic perfor-mance modelling for several project alternatives. Itwill yield a first estimate of the levelised electricitycost and of the economic perspectives of the pro-ject. The study will give the general project outlineslike administrative requirements, expected environ-mental impacts, viable schemes of finance and aproject implementation structure. This phase willyield a pre-selection and recommendation for themost promising sites. The study will be the basis forthe decision about the continuation of the project.
Step 3: Project Definition
A feasibility study will analyse the most promisingproject configuration identified in the pre-feasibilityphase, going into detail in resource assessment,thermodynamic and economic performance calcu-lations, and specifying major equipment and invest-ment estimates based on budgetary quotes. Usually,an environmental impact study is included. As aresult, the project site will be selected and thenecessary land will be reserved or purchased by theproject company. The study will be the basis for aconstruction bid and for the related Engineering,Procurement and Construction (EPC) contract, aswell as for all the legal and administrative require-ments to start the project.
Step 4: Engineering-Procurement-Construction
A consortium bidding for the EPC contract shouldconsist of the construction company, power blocksupplier, solar plant supplier and an engineeringcompany, all of whom will be experienced in CSPtechnology. The basis for this phase is a reliablescheme of finance (next page) that allows for elec-tricity costs equivalent to the expected revenues.Due to the fact that fuel is substituted by capitalgoods, a long term power purchase agreement is
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INITIATING CSP PROJECTS
1 Basic Project Information
2 Project Assessment
3 Project Definition
4 Engineering
Procurement
Construction and Civil Works
Commissioning
5 Operation and Maintenance
25 – 30 yearsthird yearsecond yearfirst year
Project Development Engineering, Procurement, Construction Operation
Timeline of initiating CSP Projects.
a major pre-requisite for the realisation of CSPplants. The final activity of this phase is the gridconnection and commissioning of the plant.
Step 5: Operation
Operation of the CSP plants is expected to last overan economic life cycle of 25 to 30 years.
Financing
Solar collectors increase the initial investment andthe related capital cost in comparison to fuel-firedpower plants. Interests for extra debt and equity,insurance costs, taxes and custom duties have to bepaid, extra land has to be purchased and extra staffhas to be employed. In contrast to that, fuels arepurchased without any interest or insurance rates,and are often free of custom duties and taxes oreven subsidised by the government. Therefore, CSP
requires start-up finance to enter the market and tofollow the learning curve. This can be achieved byan instrument such as the Spanish RenewableEnergy Act expected to become operational for CSPby the end of 2002. It will grant a revenue of 15 ct/kWh for CSP plants with maximum 50 MW ofpower, and operated in solar-only mode. For develo-ping countries, a grant by the Global EnvironmentalFacility (GEF) of approximately 50 million Euro perplant is expected to be applied to projects inMexico, Morocco, India and Egypt.
In order to achieve affordable costs today, a combi-nation of financial mechanisms including public-private risk sharing must reduce the capital cost. Inaddition to the GEF-grant and to CO2-Credits fromthe Clean Development Mechanism, all stakeholdersof a CSP project including host countries, banks,investors, insurers and suppliers are encouraged tocontribute to start-up financing by adapting theirprofit expectations to the learning curve.
Private participation in start-up finance will requirean international public-private-partnership over thewhole phase of market introduction in order toreduce the project related risks for all stakeholdersto a minimum.
During an executive conference on CSP organisedby BMU, KfW and GEF in Berlin in June 2002, the“Berlin Declaration” was issued by an internationalgroup of stakeholders that agreed to jointly developa long term strategy for the market introduction,and to discuss different innovative models of finan-ce in order to start a series of CSP projects.
http://www.en-consulting.com/csp
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PARAMETERS FOR ELECTRICITY COST CALCULATION:
General calculation parameters: Hybrid 200 MW parabolic trough steam
cycle power plant in medium load, solar share 45 %, annual electricity
1000 GWh/year, investment 425 million Euro, real discount rate 3.5 %,
economic life 25 years, fuel cost 12 Euro/MWh, avoided CO2 310,000 t/year.
Parameters for conventional financing and (in brackets) ideal para-
meters for preferential start-up financing (PF): Debt interest rate
8 %/year (4 %/year), internal rate of return of equity 20 %/year
(8 %/year), insurance rate 1 % (0.5 %) of inv./year, property tax 1.5 %
(0 %) of inv./year, income tax 38 % (0 %) of income/year, custom duty
5 % (0 %) of direct investment, production overhead 10 % (5 %), grant
0 million Euro (50 million Euro), CO2-credit 0 Euro/t (5 Euro/t), risk mana-
gement private (private & public).
L e v e l i s e d E l e c t r i c i t y C o s t i n c t / k W h
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Conventional Finance 50 Mio. Euro Grant Preferential Financing (PF) PF and CO2-Credits
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Income Tax
Property Tax
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Equity
Debt Service
O & M
Fuel
PF and CO2-Credits
Fictitious hybrid CSP start-up project showing the effects of several strategies of finance on the levelised electricity cost.
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In many regions of the world, every square kilo-metre of land can produce as much as 200 to 300 GWh/year of solar electricity using CSP techno-logy (top). This is equivalent to the annual pro-duction of a conventional coal or gas fired 50 MWpower plant or – over the total life cycle of a CSPsystem – to the energy contained in 16 million bar-rels of oil. The exploitation of less than 1 % of thetotal CSP potential would suffice to meet the recom-mendations of the Intergovernmental Panel onClimate Change (IPCC) for a long-term stabilisationof the climate. At the same time, concentratingsolar power will become economically competitive
with fossil fuels. This large solar power potentialwill only be used to a small extent, if it is restrictedby the regional demand and by the local technolo-gical and financial resources. But if solar electricityis exported to regions with a higher demand andless solar energy resources, a much greater part ofthe potential of the sunbelt countries could be har-vested for the protection of the global climate.Some countries like Germany already consider theperspective of solar electricity imports from NorthAfrica and Southern Europe as a contribution to thelong-term sustainable development of their powersector (bottom and next page).
Time series of load and power generation in Germany for a summer week in the year 2050 in a scenario aiming at environ-mental and economic sustainability. Import of solar electricity will have the important role of filling the gap between the electricity demand and the supply from national renewable power sources. CHP: combined heat and power.
World wide potential of solar electricity generation by CSP in GWh/km2 year (based on radiation data from G. Czisch, ISET).
Monday Tuesday Wednesday Thursday Friday Saturday Sunday
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P o w e r S u p p l y ( G W )
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Land area theoretically required by CSP to supply the total expected world electricity demand of 36,000 TWh/year in the year 2050
POTENTIAL AND PERSPECTIVES OF CSP
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CSP Technology for the World Market
German companies are among the world leadingtechnology providers and project developers of con-centrating solar power. The parabolic trough plantsin California, the EUROTROUGH, the EURODISH, thePS10 power tower, and lately, the pressurised air re-ceiver SOLGATE have been developed and producedwith major participation of German companies andresearch centres, most of them represented in theEuropean Solar Thermal Power Industry AssociationESTIA. With financial support from the GermanFederal Ministry for Economic Cooperation andDevelopment (BMZ) and the GEF, India will build itsfirst concentrating solar power plant in Mathania,State of Rajastan.
50 % Renewable Energy Share in 2050
The energy policy target for Germany is to reach a50 % renewable energy share by the year 2050,including national resources and renewable electri-city imports (top). The instruments to reach thisgoal range from the Renewable Energy Sources Act
to the political and financial support of researchand development of renewables, among many otherinitiatives. The German Federal Ministry for theEnvironment (BMU) encourages the development ofa long-term strategy for CSP market introduction,finance and market expansion.
R&D for Cost Reduction
Since the present cost of CSP technologies is amajor barrier to their commercialisation, theFederal Ministry for the Environment, with 10 mil-lion Euro plus 7 million Euro of industrial contribu-tions, is funding research and development in orderto reduce costs and bring CSP into the position tosuccessfully enter the market. Germany has beenactive in many international research and develop-ment activities of the European Commission andwithin the International Energy Agency’s SolarPacesProgramme.
http://www.dlr.de/systemhttp://www.swera.unep.net/http://www.bmu.de http://www.solarpaces.org/csp_docs.htm
THE MISSION OF GERMANY
E l e c t r i c i t y G e n e r a t i o n ( T W h / y e a r )
S o u r c e : D L R
Electricity supply within a sustainable energy scenario for Germany. After 2030, renewable electricity will increasingly beemployed for the generation of hydrogen for the transportation sector.
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Import Solar
Photovoltaik
Geothermal
Wind
Hydro
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CHP fossil
Gas / CC
Coal / Steam
Nuclear
Published by: The Federal Ministry for the Environment, Nature Conservation and Nuclear Safety (BMU)Public Relations DivisionD-11055 Berlin, GermanyE-Mail: [email protected]: http://www.bmu.de
This publication forms part of the information activities of Germany’s Federal Government.It is available free of charge and is not to be sold.
IT’S OUR FUTURE.
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German Basic Law, Article 20 A