Impact of degradation on system performance

Transcription

1 Impact of degradation on system performance May , Madrid Peter Schöttl, Theda Zoschke, Thomas Fluri, Anna Heimsath Slide 1

2 Motivation Degradation of primary mirrors Degradation of secondary mirrors Degradation of receiver Corrosion Impact of degradation on performance and efficiency Impact on system performance Feedback to engineering and investors Economic impact Most important parameters Feedback to material development Slide 2

3 Agenda Simulation methods Optical simulation System simulation Degradation modeling Cost calculation Slide 3

4 Agenda Simulation methods Optical simulation System simulation Degradation modeling Cost calculation Slide 4

5 Optical Simulation Raytrace3D Monte-Carlo ray tracing Simulation of large heliostat fields (>50k heliostats) Fast annual simulations with sky discretization approach Input for detailed thermo-hydraulic receiver models Slide 5 Left: Ivanpah re-modeling, ~55k heliostats Right: Solar Two model

6 System Simulation ColSim CSP Model for each component with inputs, outputs and parameters Parameter Parameter Parameter Input Input Input Component A Component B Component C Output Output Output Quasi dynamic system simulation Capacity of HTF and piping considered Modeling of transient behavior Integration of component models into system model Slide 6

7 System Simulation ColSim CSP Adjustable level of detail Fast annual simulations Variable time step length Parallel simulations for optimization purposes Based on CSPBank standards / Solar Paces Guideline Validated against data from large-scale PTC plant in Spain Annual energy yield mean deviation: 1.37 % Slide 7

8 System Simulation CRS Receiver Model Slide 8

9 System Simulation PTC/LFC Collector Model η 0 IAM curve (IA) Heat loss correlation (θ node ) Q solar,1 Q solar,2 Q solar,n Outputs: Gained energy Defocussing losses Fluid properties at outlet HTF θ node 1 θ node 2 θ node n Q loss,1 Q loss,2 Q loss,n Slide 9

10 System Simulation PTC/LFC Collector Model η 0 (t) IAM curve (IA) Heat loss correlation (θ node,t) Q solar,1 Q solar,2 Q solar,n Outputs: Fluid properties at outlet Gained energy Defocussing losses HTF θ node 1 θ node 2 θ node n Q loss,1 Q loss,2 Q loss,n Thermal resistance model (TRM) applied to consider change in emissivity in absorber tubes (PTC and LFC) and estimate temperatures at secondary of LFC Look up table for time dependent heat loss? Slide 10

11 Agenda Simulation methods Optical simulation System simulation Degradation modeling Cost calculation Slide 11

12 Degradation Modeling Impact on Yield Category 1: Direct influence on yield simulation and cost calculation Change of physical parameter over time t, e.g.: Clean Refl.=f(t, A, B, ) where A, B, are specific for site and operation (e.g. site corrosivity) Free parameters allow for sensitivity analysis EXEMPLARY: change of primary mirror clean reflectance over time, with replacements Slide 12

13 Degradation Modeling Impact on Costs Category 2: No direct influence on yield simulation Modeling of replacement frequency Integration in cost calculation EXEMPLARY: increasing molten salt costs over time due to replacements Slide 13

14 Degradation models and parameter Document for prioritization of degrading parameters Template for material degradation models Slide 14

15 Degradation models and parameter Modelling of change of functionality with time, optional consideration of temperature (eg. CRS receiver) and corosivity of site Replacement rates in plant lifetime for reflector, absorber Representative values to be defined Parameter Mirrors Primary mirror solarweighted hemispheric reflectance Secondary mirror solarweighted hemispheric reflectance Value (appr ox.) To be discussed in Workshop Expected max. +/- variation from abs. value Require d replace ment frequen cy 93% X% X / a 93% X% X / a Parameter Absorber Value (approx.) Expected max. +/- variation from abs. value Mechanical stability (corrosion) X / a Envelope tube coating - Solar x% X% X / a transmittance Absorber tube coating - Solar x absorptance Absorber tube coating - IR x% X% X / a emittance Vacuum quality x X% X / a Required replaceme nt frequency Slide 15

16 Agenda Simulation methods Optical simulation System simulation Degradation modeling Cost calculation Slide 16

17 Cost Calculation Definitions Plant lifetime: T [a] Investment costs: C capex Operation and maintenance costs: C opex /a Replacement/recoating costs: C repl,t /a Annual yield: AY t [MWh/a] Annually averaged selling price: St [ /MWh] Slide 17

18 Cost Calculation Option 1: LCoE Annuity factor with interest rate i: Plant lifetime: T [a] ANF = 1 + i n i 1 + i n 1 Investment costs: C capex Operation and maintenance costs: C opex /a Replacement/recoating costs: C repl,t /a Levelized Cost of Electricity: LCoE = C T capex ANF T + t=1 C opex + C repl,t Δt T AY t Δt t=1 Annual yield: AY t [MWh/a] Annually averaged selling price: S [ /MWh] Metric is profoundly established in the CSP community Metric allows the comparison of different technologies/materials Slide 18

19 Cost Calculation Option 2: IRR Annual Cash Flow: CF t = AY t St C opex Δt C repl,t Δt Plant lifetime: T [a] Investment costs: C capex Operation and maintenance costs: C opex /a Internal Rate of Return IRR: Replacement/recoating costs: C repl,t /a C capex + T t=1 CF t 1 + IRR t = 0 Annual yield: AY t [MWh/a] Annually averaged selling price: S [ /MWh] Metric allows the assessment of the profitability of a plant as revenues and expenditures are considered Slide 19

20 Summary Transient system simulation for annual yield assessment Degradation modeling Category 1: Impact on system performance Category 2: Impact on costs Techno-economic assessment by means of LCoE and/or IRR Slide 20

21 Questions What kind of degradation do you experience in your plants? What is the importance of the individual degradation mechanisms? How big is the impact on the overall plant performance? How do you consider degradation in your performance models? How do you consider degradation in your financial models? What are your replacement strategies (eg. For absorbers)? How do you detect component failure? Do you consider degradation of Balance of Plant? What is the mirror breakage rate in your plant? What are your testing strategies/schedules/intervals? Efficiency vs. downtime; How do you deal with this? Slide 21

22 Questions Impact of a higher temperature range of the molten salt in electricity production What are the major causes of degradation on CSP? What are the major actions to inhibit the degradation on CSP? Efficiency of the plants? Where it can be improved? Impact of coating degradation on performance and yield Slide 22

23 Thank you for your attention! Fraunhofer Institute for Solar Energy Systems ISE Thomas Fluri, Peter Schöttl, Theda Zoschke, Anna Heimsath Slide 23