High Temperature Thermal Energy Storage Development at DLR ECI - PowerPoint PPT Presentation

High Temperature Thermal Energy Storage Development at DLR ECI – Massive Energy Storage Conference, Newport Beach, June 23-26 2013 M. Eck, D. Laing, W.-D. Steinmann, S. Zunft German Aerospace Center Institute of Technical Thermodynamics

www.DLR.de/TT • slide 2 > Thermal Storage Development at DLR > Markus Eck > Massive Energy Storage > Newport Beach >June 2013 Outline Introduction / Motivation  Phase change media (PCM) storages  Compressed air energy storages (CAES)  Cell-Flux storage concept  Conclusions / Outlook  Source: Solar Millennium

www.DLR.de/TT • slide 3 > Thermal Storage Development at DLR > Markus Eck > Massive Energy Storage > Newport Beach >June 2013 Introduction / Motivation Technical options for thermal energy storages in CSP plants Heat Transfer Fluid Collector System Pressure Temperature synthetic oil trough/Fresnel 15 bar 400°C Heat Engine saturated steam tower/Fresnel 40 bar 260°C ORC superhaeted steam trough/Fresnel 50-120 bar 400-500°C storage steam turbine molten salt tower/trough 1 bar 500-600°C gas turbine system air tower 1 bar 700-1000°C Stirling engine air tower 15 bar 800-900°C others new concepts ONE single storage technology will not meet the unique requirements of different solar power plants

www.DLR.de/TT • slide 4 > Thermal Storage Development at DLR > Markus Eck > Massive Energy Storage > Newport Beach >June 2013 Introduction / Motivation Thermal energy storages under Development at DLR  Sensible heat storages  Molten Salt CellFlux Concept  Concrete  Regenerator Storages Compressed Air Energy Storages  Latent Heat Storages  Phase Change Media Nitrate Salts  Thermochemical Storages  Limestone

www.DLR.de/TT • slide 5 > Thermal Storage Development at DLR > Markus Eck > Massive Energy Storage > Newport Beach >June 2013 Phase change media (PCM) storages Fundamentals Solar Receiver Fresnel Solar tower solar field Parabolic solar field Super- heating Preheating 16% 19% 260°C – 400°C 107 bar Evaporation 65%

www.DLR.de/TT • slide 6 > Thermal Storage Development at DLR > Markus Eck > Massive Energy Storage > Newport Beach >June 2013 Phase change media (PCM) storages Fundamentals 1000 900 800 Fluoride Schmelzenthalpie [J/g] Heat of Fusion [J/g] 700 600 500 Hydroxide 400 Carbonate und Wasser Chloride 300 Salz- Salz- Nitrate Wasser hydrate 200 Paraffine 100 0 -100 0 100 200 300 400 500 600 700 800 900 1000 Temperatur [°C] Temperature [ ° C]

www.DLR.de/TT • slide 7 > Thermal Storage Development at DLR > Markus Eck > Massive Energy Storage > Newport Beach >June 2013 Phase change media (PCM) storages Current Materials Nitrate salt represent possible PCMs for applications beyond 100 ° C Important PCM criteria: thermal conductivity, melting enthalpy, thermal stability, material cost, corrosion, hygroscopy 400 400 LiNO 3 LiNO 3 350 350 300 300 LiNO 3 -NaNO 3 LiNO 3 -NaNO 3 Enthalpy [J/g] Enthalpy [J/g] 250 250 NaNO 2 NaNO 2 200 200 NaNO 3 NaNO 3 KNO 3 -LiNO 3 KNO 3 -LiNO 3 150 150 KNO 3 -NaNO 2 -NaNO 3 KNO 3 -NaNO 2 -NaNO 3 KNO 3 -NaNO 3 KNO 3 -NaNO 3 KNO 3 KNO 3 100 100 50 50 0 0 100 100 150 150 200 200 250 250 300 300 350 350 Temperature [°C] Temperature [°C]

www.DLR.de/TT • slide 8 > Thermal Storage Development at DLR > Markus Eck > Massive Energy Storage > Newport Beach >June 2013 Phase change media (PCM) storages Challenges liquid liquid solid solid Fluid Fluid Source: DLR schematic PCM-storage concept Phase Change Material (PCM) Heat transfer coefficient is Tube dominated by the thermal conductivity of the solid PCM Heat carrier: water/steam → Low thermal conductivity is Finned Tube Design Fins bottleneck for PCM effective λ > 10 W/mK

www.DLR.de/TT • slide 9 > Thermal Storage Development at DLR > Markus Eck > Massive Energy Storage > Newport Beach >June 2013 Phase change media (PCM) storages Development of Prototypes Phase change media Demonstrated at DLR: NaNO 3 - KNO 3 - NaNO 2 142°C LiNO 3 - NaNO 3 194°C NaNO 3 - KNO 3 222°C NaNO 3 306°C Experimental validation 5 test modules with 140 – 2000 kg PCM Worlds largest high temperature latent heat storage with 14 tons of NaNO 3 (700 kWh) operating 2010-11

www.DLR.de/TT • slide 10 > Thermal Storage Development at DLR > Markus Eck > Massive Energy Storage > Newport Beach >June 2013 Phase change media (PCM) storages Latest Demonstrator PCM-Evaporator module:  Capacity ~ 700 kWh  PCM: NaNO 3  Melting point: 306°C  Salt volume: 8.4 m³  Total height 7.5 m  Inventory ~ 14 t

www.DLR.de/TT • slide 11 > Thermal Storage Development at DLR > Markus Eck > Massive Energy Storage > Newport Beach >June 2013 Phase change media (PCM) storages Current Developments at DLR Enhanced heat transfer by extruded longitudinal fins Cost-effective production and assembly  Free flow path in vertical direction  => no risk with volume change during phase change Source: DLR Controlled distribution of heat in the  storage Concept optimized by FEM analysis  Successful demonstration in lab-scale  Major cost reduction expected 

www.DLR.de/TT • slide 12 > Thermal Storage Development at DLR > Markus Eck > Massive Energy Storage > Newport Beach >June 2013 Compressed Air Energy Storages (CAES) Fundamentals Objectives: • Peak load/Reserve power 300 MWel, 4-8 turbine full load hrs. -> supports grid integration of RE • Highly efficient due to storage-based heat management -> ~70% storage round-trip efficiency • TES technology: Direct contact solid media storage („regenerator storage“) • Specifications: ~600 ˚ C @60 bar • Design aspects: best heat transfer, fast start-up, efficient solutions for HT-insulation, solutions for pressurised containment, durability of materials in hot & humid atmosphere

www.DLR.de/TT • slide 13 > Thermal Storage Development at DLR > Markus Eck > Massive Energy Storage > Newport Beach >June 2013 Compressed Air Energy Storages (CAES) Chosen Concept • Direct contact between HTF and storage medium • High temperature applications, simple setup • Broad choice of applicable inventory materials • Typical setup: stacked bricks, packed beds allow cost reduction • Challenges: Thermo-mechanical aspects (packed beds), fluid- dynamic aspects, durability/erosion, containment

www.DLR.de/TT • slide 14 > Thermal Storage Development at DLR > Markus Eck > Massive Energy Storage > Newport Beach >June 2013 Compressed Air Energy Storages (CAES) Current Development at DLR • Develop tools and design solutions for optimized thermal design • Tools and design solutions considering the thermally induced mechanical loads in large-scale packed storage (particle- discrete simulation) • Develop design solutions for the fluid dynamic aspects (flow distribution, pressure loss) • Reduce lifetime uncertainty of materials through extensive material testing • Validate TES design solutions through pilot-scale testing

www.DLR.de/TT • slide 15 > Thermal Storage Development at DLR > Markus Eck > Massive Energy Storage > Newport Beach >June 2013 CellFlux Storage Concept Motivation Solid Storage Media (Concrete) Liquid Storage Media (Molten Salt) Structure of capital costs Molten Salt 49% Heat Exchanger 57% Limited potential for further cost reductions due to physical constraints  New Basis Concept required

www.DLR.de/TT • slide 16 > Thermal Storage Development at DLR > Markus Eck > Massive Energy Storage > Newport Beach >June 2013 CellFlux Storage Concept Innovative approach solid state storage media cost effective no freezing Requirements - Large heat transfer surfaces (short path length for heat conduction within solid storage material) - Direct contact between storage medium and working fluid (no expensive piping / coating) - Storage volume at atmospheric pressure (no expensive pressure vessels)

www.DLR.de/TT • slide 17 > Thermal Storage Development at DLR > Markus Eck > Massive Energy Storage > Newport Beach >June 2013 CellFlux Storage Concept Innovative approach from solar field Problem: closed air cycle Low volume specific energy density of air Storage volume • large pressure losses Heat • part load operation difficult exchanger Fan to solar field

www.DLR.de/TT • slide 18 > Thermal Storage Development at DLR > Markus Eck > Massive Energy Storage > Newport Beach >June 2013 CellFlux Storage Concept Innovative approach

www.DLR.de/TT • slide 19 > Thermal Storage Development at DLR > Markus Eck > Massive Energy Storage > Newport Beach >June 2013 CellFlux Storage Concept Current Development at DLR • Theoretical and experimental investigation of sub-system behavior • Design and construction of demonstration plant • Development of design and sizing tools Start and End Temperature Profile with 2°C Maximum Rise of ExitTemperature 400 2°C Exit Temperature Rise 380 Storage Material Temperature [°C] 360 Usage of Storage 340 Initial Temperature Profile 320 End Temperature Profile 300 280 0 5 10 15 Flow Length of Storage [m]