Solar Boiler Concept for Concentrating Solar Power Plants. Ulrich Hueck, Dr.-Ing. Co-Founder

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1 Solar Boiler Concept for Concentrating Solar Power Plants Ulrich Hueck, Dr.-Ing. Co-Founder Frankfurt am Main June 5, 2013

2 Different designs exist for CSP units Layout for concentrating solar power Linear concentration Absorber Receiver Tube tube Absorber Receiver tube and reconcentrator re-concentrator Mirrors Concentration: Temperature: ~400 C Unit size: MW Efficiency: 15 16% Curved mirror Pipe with thermal fluid Parabolic trough Linear Fresnel Concentration: Temperature: ~400 C Unit size: MW Efficiency: 8 10% Point concentration Concentration: >1000 Temperature: ~1200 C Unit size: MW Efficiency: 20 25% Receiver // Engine engine Reflector Dish Stirling Solar Receiver receiver Heliostats Central receiver Concentration: Temperature: ~1200 C Unit size: MW Efficiency: 15 17% Data subject to change due to further development of technologies CSP = Concentrated Solar Power 2

3 Which way is the best? Use of solar radiation for power generation favourable unfavourable 3

4 Hilly or horizontal surfaces? Area for solar thermal power plants Possibility to build on hilly areas** Restriction to horizontal surfaces* * Solar thermal plants with parabolic trough mirrors or Fresnel shape mirror assemblies are restricted to horizontal surfaces. ** Solar thermal tower plants with a central receiver can be built on hilly areas, but horizontal surfaces are still favourable. 4

5 Flat* or curved mirrors? Mirrors for solar thermal power plants Simple manufacturing More complex manufacturing * Flat mirrors for solar tower power plants have a slight curvature to focus the solar radiation. 5

6 Parasitic power consumption should not increase with the size of the solar field Size of solar thermal power plants Allow for low focussing accuracy of remote mirrors* Power consumption of HTF pump increases with size of solar field * Distance of remote mirrors restricted by radiation losses through the lowlying atmosphere. HTF = Heat Transfer Fluid 6

7 The type of solar radiation concentration impacts the technical effort involved Heating with solar radiation Point concentration Bundled concentration Effort due to very large amount of heat on small surface area Optimization of radiation per unit of surface area Short medium path Simpler insulation Cold medium Hot medium 7 Linear concentration Pipe Effort for medium transport and vacuum insulation with glass

8 Solar receivers must minimize heat losses to the environment Use of waste heat from solar radiation Heat losses to the environment Capture of heat losses Utilization of waste heat Receiver Solar radiation Emitted heat 8

9 The quantity of thermal cycles impacts the technical effort involved Heat transfer cycles for power generation Additional cycle with thermal oil or molten salt or hot air Heat exchangers between first and second cycle Only one cycle with water/steam Steam turbine 9

10 High inlet temperatures in thermal power machines are advantageous for the efficiency of the power plant Carnot s theorem for maximum efficiency T H limited through heat transfer fluid* Design should allow for operating at increasingly high temperatures η =η max Carnot = 1 - T T C H T H Steam turbine T H is the absolute temperature of the hot reservoir T C is the absolute temperature of the cold reservoir * The common heat transfer fluid Therminol VP-1 for parabolic trough solar fields restricts the maximum temperature to 400 C T C 10

11 Conventional boilers can serve as the basis for solar steam generation Multi-segment solar boiler Focussing accuracy matching temperature Steam superheating* Utilization of waste heat Uneven ground is permissible Water Solar economizer Solar evaporator Solar superheater Steam Steam Solar reheater Utilization of insulating and cooling air for preheating of condensate and feedwater *Sophisticated control of disturbances through clouds required. June 2013: Testing at CISRO in Australia Graphic left: Javier Muñoz, Alberto Abánades and José M. Martínez-Val Universidad Politécnica de Madrid A conceptual design of solar boiler Solar Energy 83 (2009) pp Graphic right: Ulrich Hueck 11

12 The solar boiler could be tested at a conventional steam power plant* Small prototype of a solar boiler Steam turbine Solar boiler prototype Low costs Fast implementation Fuel savings Fossil-fired boiler Condenser Superheated steam Feedwater Daytime operation 24 h operation * Testing at fossil desalination plants might also be possible. Source: Ulrich Hueck DESERTEC Foundation An Innovative Concept for Large-Scale Concentrating Solar Thermal Power Plants in Stolten / Scherer: Transition to Renewable Energy Systems pp Wiley-VCH Weinheim

13 It is possible to reduce the time required for the installation of several prototypes Development of prototypes 1 st prototype 2 nd prototype 3 rd prototype Preparation Design Implementation Testing Consecutive development 1 st prototype Consideration of feedback 2 nd prototype Parallel development Faster implementation 3 rd prototype 13

14 The concept for the solar boiler is derived systematically and explained Publication about solar boiler Ulrich Hueck DESERTEC Foundation An Innovative Concept for Large-Scale Concentrating Solar Thermal Power Plants in Stolten / Scherer: Transition to Renewable Energy Systems pp Wiley-VCH Germany