Status and Perspectives of CSP Technology. Robert Pitz-Paal

Status and Perspectives of CSP Technology Robert Pitz-Paal

DLR.de Chart 2 Outline 1. Characteristics of CSP 2. Market und Cost Development 3. Benefits for a mix of PV und CSP 4. Innovation to drive cost reduction 5. Conclusions

DLR.de Chart 3 Outline 1. Characteristics of CSP 2. Market und Cost Development 3. Benefits for a mix of PV und CSP 4. Innovation to drive cost reduction 5. Conclusions

www.dlr.de Folie 4 What is CSP? Conventional power plant 4

www.dlr.de Folie 5 What is CSP? Concentrating solarpower plant 5

DLR.de Chart 6 Trough vs. Tower Point Focus Line Focus DLR

DLR.de Chart 7 Trough vs. Tower Solar energy collected by reflection Solar energy collected by piping

DLR.de Chart 8 Characteristics Solar Resource PV direct und diffuse radiation CSP direct Radiation Block size mwatt to some 100 10 MW to some 100 MW Installation: Capacity : Back-up Capacity Inst. Power (2016) LCOE everywhere (roof top) etc.) 700 2000 full load hours external (e.g. gas turbine) 305 GW 0,03 0,13 /kwh flat unused land 2000 7000 full load hours therm. Storage / fossil backup 5 GW 0,06 0,12 /kwh

DLR.de Chart 9 Thermal Storage vs. Electric Storage η >95 % +2000 h 2000 h Firm capacity 200 h CSP with thermal storage and fossil back provides reliable dispatchble power at no additional cost η = 75%

DLR.de Chart 10 CSP only suitable in areas with high direct normal radiation

DLR.de Chart 11 High shares of cheap Wind and PV capacity lead to a strongly fluctuating residual load that need to covered by other technologies

DLR.de Chart 12 PV and CSP Two technologies that complement each other perfectly in many regions of the world, in particular if large shares fossil fuel can not be used Scenario for Electricity Supply for North Africa for 2015 based on high shares of renewable energies * *Results from the EU Better Study (www.better-project.net)

DLR.de Chart 13 Outline 1. Characteristics of CSP 2. Market und Cost Development 3. Benefits for a mix of PV und CSP 4. Innovation to drive cost reduction 5. Conclusions

DLR.de Chart 14 Global expansion of CSP in three phases Lilliestam, J., Labordena, M., Patt, A. & Pfenninger, S. Nat. Energy 2, 17094 (2017).

www.dlr.de Chart 15 Market Development CSP Installed power (cumulated, GWe) 70 60 50 40 30 20 10 8.5 GWe will be installed until 2020 Currently 2 GWe under construction 5 GWe installed in 2015 18.5 GWe planned until 2025 depend on cost development Confirmed 0 Planned 2010 2015 Year 2020 2025 historisch Heliokon Tower Trough Significant change in market share between Power Tower and Trough 2020 Tower 40% 40% 2025 Tower 2020 Trough 60% 60% 2025 Trough

DLR.de Chart 16 Cost reduction over last 5 years at a learning rate of > 25% Lilliestam, J., Labordena, M., Patt, A. & Pfenninger, S. Nat. Energy 2, 17094 (2017).

www.dlr.de Chart 17 Cost for CSP and PV have dropped dramatically Installed CSP capacity is more than an order of magnitude smaller than PV capacty Energy sales price PV Module price PV 2007 Energy sales prices CSP 2014 Dubai 2017 Chile 2016 Australia 2017 2014 2016

DLR.de Chart 18 Solar electricity competive with natural gas? 700 MW @ 5500 h CSP á 7,3 $cents/kwh + 800 MW @ 2300 h PV a 3 $Cents/kWh = 5,95 $cents/kwh = 5,07 cents/kwh for 24/7 electricity More than 5000 full load hours

www.dlr.de Chart 19 What is behind these numbers? Example Dubai: DEWA Project: What do we know? PPA Price 7,3 $cents/kwh PPA duration 35 years Total investment 3 900 Mio.$ = 5570 $/kw Solar Resource: ~2200kWh/m²a average of 12 hours of storage What we don t know Capacity factor of plant? O&M cost? Let try to estimate 60% 2% of invest Result in financing conditions (WACC) 4,8%

www.dlr.de Chart 20 What does a WACC of 4,8% mean? All these constellations leads to a WACC of 4,8% Loan Period 35y 35 y 35y Equity share 20% 30% 20% Loan interest 2,5% 2,5% 3,5% IRR 6,1% 5,0 % 2,8% (during loan period) Very low financing conditions, compared to other markets Places with better solar resources may allow for higher financing cost at the same electricity price

DLR.de Chart 21 Outline 1. Characteristics of CSP 2. Market und Cost Development 3. Benefits for a mix of PV und CSP 4. Innovation to drive cost reduction 5. Conclusions

Chile Scenario Results Expansion Model Scenario 1 Social acceptance Energy demand Technological change in BESS Externality costs RE investment costs Fossil fuel costs CSP LCOE Scenario B High High Low High Low High USD 50 /MWh by 2025 [MW] x 10000 6 5 4 3 2 1 0 2029 Installed Capacity Pump Battery CSP_Solar PV_Solar Wind Other Hydro_NCRE Hydro_ROR Hydro_Dam Diesel LNG Geothermal Biomass Coal

Chile Scenario Results Expansion Model Scenario 1 Social acceptance Energy demand Technological change in BESS Externality costs RE investment costs Fossil fuel costs CSP LCOE Scenario B High High Low High Low High USD 50 /MWh by 2025 [GWh] x 10000 25 20 15 10 5 0 2029 Generation Battery Pump Diesel PV_Solar CSP_Solar Wind Hydro_ROR Hydro_NCRE Geothermal Other Biomass LNG Hydro_Dam Coal

Chile Szenario results: Short Term Simulation 2035 summer week dispatch by technology 20000 CSP Power (MW) 15000 10000 5000 0 PV_SOL CSP_SOL LNG_CCGT LNG_GT WIND HYDRO_ROR HYDRO_DAM GEO DIE COG BIO COAL

DLR.de Chart 25 Outline 1. Characteristics of CSP 2. Market und Cost Development 3. Benefits for a mix of PV und CSP 4. Innovation to drive cost reduction 5. Conclusions

DLR.de Chart 26 Advanced Silicon Oil in Parabolic Troughs Environmental Safety Capacity / Performance low pour point (-55 C) reduces auxiliary consumption for freeze protection slower degradation at 425 C in comparison to DPO/BP at only 400 C 425 C field outlet temperature increases conversion efficiency of Rankine cycle and allows for smaller heat storage systems

DLR.de Chart 27 Advanced Silicon Oil in Parabolic Troughs Enhanced thermal stability A A A Comparison of DPO/BP at only 400 C with HELISOL 5A at 425 C Considerably slower formation of low boiling degradation products Less hydrogen formation (enhanced receiver lifetimes expected)

DLR.de Chart 28 Advanced Silicon Oil in Parabolic Troughs Heat transfer fluid DPO/BP HELISOL 5A Unit Nominal solar field temperature C 393 430 A Gross power block efficiency (wet cooling) % 39.0 40.5 Gross power block efficiency (ACC) % 37.7 39.2 Nominal specific solar field parasitics W/m² 8 6.4 Specific investment solar field /m² 235 235 Specific investment storage /kwh 40 33 Specific HTF cost (identical) /kg 4 4 Annual HTF replacement rate (identical) % 2 2 Mean volumetric heat capacity kj/(m³k) 1871 1397 Benefits over DPO/BP state-of-the-art thermal oil Increased performance due to higher live steam temperatures Lower storage costs due to increased temperature spread LCOE by cost reduction potential of about 5% for different sites and plant sizes

DLR.de Chart 29 SITEF Project 2016-2017 German-Spanish cooperation PROMETEO test facility at Plataforma Solar de Almería (Spain) Durability and loop scale applicability of HELISOL 5A at 425 C Comprehensive laboratory analysis degradation Functionality parabolic trough collector components at up to 450 C Receiver Tubes Rotation and expansion performing assemblies Economic benefit of HELISOL 5A technical investments / greater energy output Safety concept and (permitting process for relevant target markets)

DLR.de Chart 30 Outline 1. Characteristics of CSP 2. Market und Cost Development 3. Benefits for a Mix of PV und CSP 4. Innovation to drive Cost reduction Near term: Advanced silicon Oil in parabolic troughs Mid term: Parabolic Trough with Molten Salt Long term: Particle Receiver Technology 5. Conclusions

DLR.de Folie 31 Molten Salt in Parabolic Trough Power Plants Thermal oil (TO) based plant Molten salt (MS) based plant Advantages of the Molten Salt System Higher overall system efficiencies due to higher working parameters (up to 565 C/150 bar instead of 400 C/100 bar) Solar Field and power block fully decoupled Lower price for heat transfer fluid (HTF), no need of heat exchangers and additional pumps Environmentally friendly heat transfer fluid vs. thermal oil

DLR.de Folie 32 Parabolic Trough Night operation /w molten salt Minimum temperature in solar field must not drop to solidification temperature of the salt Choice of salt defines hours of so called anti-freeze operation of a cooled down solar field, e.g. during night and overcast times Salt Mixtures Decomp. Temperature Freezing Temperature MS-A NaK-NO 3 (Solar Salt) >550 C 238 C @ 60/40 Mixture MS-B NaKCa-NO 3 <500 C ~150 C MS-C NaKLi-NO 3 ~530 C ~140 C Energy for anti-freeze operation during night and overcast situations is provided by the sun! Part of the thermal energy storage is reserved for anti-freeze and loaded during the day. Only in seldom cases of exception a fossil burner supports.

DLR.de Folie 33 Energy flow diagram of MS-A molten salt parabolic trough system Wirkungsgrad Solar field Tanks and AH und Kostenpotenzial Power block Optical loss PTCs 1207.8 GWh Dumping 140.9 GWh Heat loss PTRs 293.9 GWh Pump solar field 12.6 GWhe 2,1% of electricity Loss pump 7.2 GWh Heat loss tanks 8.3 GWh Pump power block 12.2 GWhe 2% of electricity Power block heat up 48.2 GWh Power block 768.1 GWh Sun 3057.2 GWh 100% Electricity 596 GWhe numerical error 0.7 GWh gross 19,2% Net 18,1% Heat loss pipings 25.6 GWh Heat loss switch steady-->transient 16.2 GWh Auxiliary heater 45.2 GWh Heat loss auxiliary heater 4.5 GWh Heat loss SG 9.8 GWh 3% of solar thermal power by fossil fuel

DLR.de Folie 34 Road map of Cost reductions for molten salt parabolic trough plants at (IRR of 8% over 25 years) 2013 Rügamer, T., H. Kamp, et al. (2013). Molten Salt for Parabolic Trough Applications: System Simulation and Scale Effects. 19th SolarPACES Conference, Las Vegas.

DLR.de Folie 35 Proof of concept needs to show: 1. Filling and draining of the plant 2. Anti-freeze parasitic load 3. Danger of freezing 4. Blackout scenarios 5. Corrosion at high temperature 6. System performance 7. Flexible connection technology: Proof of functionality and tightness 8. Steam Generating System leakage 9. Maintenance procedures 10. Stability of salt mixtures

DLR.de Folie 36 DLR s objective in Évora, Portugal: to confute all concerns Control Room Once-Through Steam Generating System W/S-Cycle Wind Fence Solar Field Site Thermal Energy Storage Drainage Tank with permanent Melting Unit HelioTrough loop will be installed Project: HPS2 High Performance Solar 2 Commissioning of the plant: January 2018 See also: http://www.dlr.de/sf/en/desktopdefault.aspx/tabid-10436/20

DLR.de Chart 37 Outline 1. Characteristics of CSP 2. Market und Cost Development 3. Benefits for a Mix of PV und CSP 4. Innovation to drive Cost reduction Near term: Advanced silicon Oil in parabolic troughs Mid term: Parabolic Trough with Molten Salt Long term: Particle Receiver Technology 5. Conclusions

DLR.de Chart 38 Long Term Perspective: Path to High Temperatures Target: higher system efficiency Increased power cycle efficiency by increased process temperatures Steam cycles with up to 620 C: η cycle up to 48% Supercritical CO 2 cycles with up to 700 C: η cycle > 50%? Higher cycle efficiency less heliostats required lower cost Higher receiver temperature: T rec > 600 C Suitable heat transfer media for higher receiver temperatures: New molten salt mixtures: cost, corrosion, degradation? Liquid metals: cost, corrosion, safety? Solid particles? Reference system: molten salt, steam cycle @540 C Bauxite particles Very high operation temperature possible (up to 1000 C) Direct absorption of solar radiation: high efficiency no solar flux density limit, less high temperature materials Direct storage of the heat transfer medium High temperature spread in storage low storage cost Low parasitic power: no freezing no trace-heating

DLR.de Chart 39 Principle of a Solar Particle System

DLR.de Chart 40 Particle Direct Absorption Receiver: Falling Film Receiver Solar tests at temperatures > 700 C Particles: sintered bauxite ( proppants ) High particle velocities might be problematic (abrasion, attrition) Particle receiver tests at Sandia Natl. Labs, USA

DLR.de Chart 41 DLR Approach: Direct Absorption Receiver: Centrifugal Receiver Rotating receiver Centrifugal force keeps particles at the wall Residence time controlled by rotational speed Good temperature control in all load situations

DLR.de Chart 42 Centrifugal Particle Receiver: 10kW Test Receiver Successful lab testing up to 900 C receiver Electric Xe arc lamps High receiver efficiency due to high flux capability

DLR.de Chart 43 Centrifugal Particle Receiver: 500kW Prototype DLR solar tower test facility in Jülich, Germany 500 kw th currently under testing >800 C particle outlet temperature already achieved

DLR.de Chart 44 Economics of Solar Particle Systems vs. State of the Art Molten Salt Tower LCoE reduction potential: about 16%

DLR.de Chart 45 Outline 1. Characteristics of CSP 2. Market und Cost Development 3. Benefits for a mix of PV und CSP 4. Innovation to drive cost reduction 5. Conclusions

DLR.de Chart 46 Conclusion PV and CSP with storage and hybridization are complementary technologies: PV provides energy CSP Energy + secured power PV market is booming since today often the most cost-effective option, CSP is at the edge of being competitive to gas in combination with PV: further cost reduction is expected Cost reduction requires higher process temperature to reach to higher solar-electric efficiency New heat transfer fluids needs to be integrated to reach higher process temperature Advanced oil, molten salt or solid particles are currently under large-scale testing to proof their feasibility