Comparison of two concepts of Solar Power Tower systems - PDF

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					Comparison of two concepts of Solar
     Power Tower systems

        Benjamin Pfluger, Christoph Kost
  Fraunhofer Institute for Systems and Innovation Research

                  WORKSHOP
 FUTURE ENERGY: Research, Innovation and Technology
                   March 3rd, Lisbon, Portugal
The Fraunhofer Institute for Systems and Innovation Research ISI is organized in seven
Competence Centers with a total of 23 Business Units, around 160 employees. In our
Competence Center we focus on energy systems and energy policy.

                                                    Fraunhofer Institute Systems and Innovation
                                                    Breslauer Straße 48, 76139 Karlsruhe, Germany
                                                    E-mail: Eichhammer@isi.fhg.de
                                                    Phone: +49 721 / 6809-168
                                                    Fax: + +49 721 / 6809-272




Slide 2
Content

1.        Main objectives of this Assessment
2.        Solar Thermal Power Concept (PS10 vs. Solar Tres)
3.        Reference Technology
4.        Concept of Technology Assessment in Eminent
5.        Results of the assessment
6.        Conclusion




Slide 3
Planned solar thermal plants in Spain




          Source: Red Electricá de Red Eléctrica de España




Slide 4
New Solar Thermal Towers in Spain


• New momentum for solar thermal tower plants in
  Spanish renewable sector after implementing a
  feed-in tariff for solar thermal technologies (Real
  Decreto 436/2004)
• Construction of two plants applying the tower
  concept (PS10 and Solar Tres)


 PS10 and Solar Tres differ in the design of
 receiver technology, fluid medium, storage
 system and some size aspects.



 Assessment to evaluate the main
 characteristics of the different technologies by
 simplifying on some parameters.




 Slide 5
Main objectives of this Assessment


                                            Assessment
                  Comparison
                                                               Testing and
                of different EST
                                                              Evaluating by
                      Tower
                                                                Eminent
                 Technologies


           Solar Tres         PS10




                                    Fluid
                   Storage                    Receiver    Generation
    Size                            heat                                 Efficiency
                   System                    technology     costs
                                   medium




Slide 6
Solar Thermal Power Concept

Main idea: Convert high direct sun irradiation into electricity

How it works:
• A solar field with mirrors is installed around a central receiver element.
• Mirrors (Heliostats) are tracking the course of the sun biaxially during the day to
  concentrate the radiation (reflector surface 20 to 150 m²).
• A central receiver is placed on the top of tower in a height of approx. 100 m.
• In the receiver the sun radiation is transformed into thermal energy by heating a heat
  transfer medium.
• The heat transfer medium is conducted to a conventional power block with steam
  turbine.
• A storage system can balance the fluctuation of sun radiation and is able to provide
  energy also during the night.
• The output of the turbine can be transmitted to the electricity grid and supply energy
  demand.
• Technology is a a very early commercial phase.




Slide 7
 PS10 (Direct Steam Generation)

• Construction: Abengoa Solar S.A.
• Location: Near Seville




Data:
                                                                        C
• Volumetric air receiver provides the saturated steam of 40 bar and 250°
• Mirror field size 75,000 m²
• Mirror surface of 121 m² each
• Thermal storage capacity of 20 MWh with steam, permitting 30 min of reduced turbine
  operation load
• Steam turbine capacity 11 MW
• Annual Production 24.3 GWh                                                      Source: Abengoa Solar




  Slide 8
 Solar Tres

• Construction: Sener S.A.
• Location: Near Écija in Andalusia




Data:
                                                             C)
• Receiver provides a fluid heat medium with molten salt (565°
• Mirror field size 298,000 m²
• Thermal storage capacity of 647 MWh with molten salt, permitting 15 hours of turbine load
• Turbine capacity 17 MW
• Annual Production 110 GWh

                                                                                    Source: Sener




  Slide 9
Solar Tres


Operation of the storage:




Slide 10
Reference Technology


  The most common CSP technology, with
  a high number of plants planned or
  under construction is parabolic trough
  design.

  The collector system of a parabolic
  trough design reflects radiation on a
  linear absorber in the focal line of the
  concentrator elements.
  Over the absorber tubes the fluid heat
  medium is also transferred to a central
  conventional power block where it can
  be stored in a thermal storage system
  and transformed in electricity by a steam
  turbine.




 Slide 11
Concept of Technology Assessment in Eminent

           Object       Comparison of two tower technologies

                        •   Using data of PS10 and Solar Tres
                        •   For each Concept different storage system
                        •   2009 is chosen as base year
            Data        •   Spanish irradiance as general resource
                        •   17 electricity demand for various sectors (Spain)
                        •   Storage systems and turbine are specified as peripheral technologies

                        • Modeling of storage technology is simplified
    Assumptions         • Storage systems are necessary to meet typical Spanish demand
                        • Several size assumptions have to be made


                       Solar field
                                                  Storage
           Sun      Solar Tres Tower                                      Gas Turbine
                                                 Molten Salt
                        Receiver


                      Solar field                  Storage
           Sun       PS10 Tower                    Steam                  Gas Turbine
                      Receiver                   Accumulator




Slide 12
Results of the assessment
    Ranking
   of chains          Parameters                             PS10                                          Solar Tres
   (by costs)
   1.           Chain description:        Solar energy -> [Solar Tower Plant steam] ->     Solar energy -> [Solar tower salt] -> Heating ->
                                          Heating -> [Steam accumulator (Storage)] ->      [Molten Salt Storage] -> [Steam Turbine] ->
                                          [Steam Turbine] -> Electricity                   Electricity

                Costs:                    202.91 EUR/MWh                                   281.38 EUR/MWh
                Total chain efficiency:   15.45 %                                          14.0 %

                Demand sector:            Mining of metal ores                             Mining of metal ores
   2.           Chain description:        Solar energy -> [Solar Tower Plant steam] ->     Solar energy -> [Solar tower salt] -> Heating ->
                                          Heating -> [Steam accumulator (Storage)] ->      [Molten Salt Storage] -> [Steam Turbine] ->
                                          [Steam Turbine] -> Electricity                   Electricity

                Costs:                    204.49 EUR/MWh                                   282.96 EUR/MWh
                Total chain efficiency:   15.45 %                                          14.0 %

                Demand sector:            Manufacture of basic precious and non-ferrous    Manufacture of basic precious and non-ferrous
                                          metals                                           metals
   3.           Chain description:        Solar energy -> [Solar Tower Plant steam] ->     Solar energy -> [Solar tower salt] -> Heating ->
                                          Heating -> [Steam accumulator (Storage)] ->      [Molten Salt Storage] -> [Steam Turbine] ->
                                          [Steam Turbine] -> Electricity                   Electricity

                Costs:                    220.86 EUR/MWh                                   299.33 EUR/MWh
                Total chain efficiency:   15.45 %                                          14.0 %

                Demand sector:            Electricity, Steam, steam and hot water supply   Electricity, Steam, steam and hot water supply




Slide 13
  Energy analysis




                     PS10                      Solar Tres



Total efficiency:            15,45 %                          14,0 %
Conclusion:
1) The results given by Eminent match the figures given by Sener and Abengoa very
   well and prove the functioning of Eminent.
2) According to information of both companies these values will increase with further
   developments in the solar collector field and receiver technology.
3) This increase could easily be respected in by changing parameters in Eminent.



   Slide 14
 Environmental analysis




                   PS10                     Solar Tres


Output of CO2:                  0                              0

Zero CO2 emission was implied for used solar thermal power generation.

Further environmental impacts like water supply, land use or destruction of
characteristic landscape have not been analysed, but some of these issues could
be interesting points for future developments of Eminent.



  Slide 15
     Economic analysis




                          PS10                         Solar Tres

Generation costs
of cheapest                     202,92 Euro/MWh                         281,39 Euro/MWh
technology chain:

1)     Eminent is able to provide a comparison of two different solar tower technology with linked
       storage technology.
2)     With the applied parameters the PS10 tower can generate electricity for Spanish demand
       cheaper than the Solar Tres tower.
3)     Prices for demand sector "Mining of metal ores" are the lowest because of highest demand
       value of this sector.
4)     Problems: Some key figures and data can hardly be quantified, e.g. value of storage.



     Slide 16
Conclusion

           The differences of the concepts, mainly the type and dimensioning
           of the storage facilities, lead to differences in efficiencies and
           generation costs.
           Generation costs of Solar Tres are 78.5 EUR/MWh higher than
           PS10 due to the storage facilities.
           Higher security of supply and more leeway to react to market prices
           have to be weighted against each other to find the most suitable
           option under given circumstances.
           Eminent can provide assistance on technical and economic
           questions.
           Possible further developments:
                   Detailed modelling of storage technologies
                   Detailed modelling of energy efficiency technologies




Slide 17
           Thank you for your attention!

               B.Pfluger@isi.fhg.de




Slide 18