1. CSP Grid Value of Energy Storage and LCOE Implications 26 August 2013

2. Overview
Background
Presentation based on a study done for Eskom’s Solar 1 CSP plant to be constructed near Upington
Study focused on the economic value of CSP Storage to the system
Considers capacity and energy value to supply demand and reserves
Detailed enough to analyse hourly profiles
Content
Methodology
Assumptions
Study
Results
2018/11/07

3. Methodology

4. Conversion of Solar Data
By System Advisor Model (SAM) of NREL
SAM
Receiver Thermal Energy Output (to Plexos)
2018/11/07

5. Modelling of CSP Generator
In Plexos, include CSP Generator as part of Supply System
Receiver Thermal Energy Output (from SAM)
Spill(a) representing “de-focusing” of Heliostat Field when Solar Energy > (Generation Capability and Storage is full)
Storage
Spill(b) representing storage heat losses = f(storage)
Energy to Generating Plant (normal Plexos modelling)
2018/11/07

6. System Modelling (Transmission not included)
“Demand side”
“Boundary conditions”
Emission Constraints
Adequacy Criteria
Ensure match of supply and demand in-stantaneously
Policy Objectives
Jobs
Localisation
Local industry …
Demand Forecast
TWh
400
Mt CO2
600
Scenarios
Scenarios
Demand-side interventions (DSM)
200
400
200
2010
2020
2030
Iterative
2010
2015
2020
2025
2030
Energy & Capacity Shortfalls
Least-cost optimisation model
One result per scenario
Plans as decision basis for DoE
TWh GW
600 80 f 60
400 40
200 20
2010
2020
2030
2010
2020
2030
“Supply side”
Committed New Builds & Decommissioning
Capacity Options
CAPEX
OPEX
Fuel costs
Load factor
Oper. regime …
Coal
Nuclear
Wind PV
CSP x 80 GW 60
Scenarios 40 20

7. Analysis Economic Analysis
CSP amount of Storage Incrementally increase hours of storage (StoreHoursi, i = 1 to n)
Determine total system cost for each increment (Plexos) [With CSP costs = 0] (SystemCostsi, i = 1 to n)
Determine total CSP cost for each increment (SAM) [CSP Cost = Capital Cost + O&M Cost + Running Cost (water)] (CSPCostsi, i = 1 to n)
Determine: Valuei+1 = SystemCostsi - SystemCostsi +1 Costsi+1 = CSPCostsi+1 - CSPCostsi
If Valuei+1 > Costsi Increase in storage is economic
System Costs include capital, fixed and variable operating and maintenance and fuel costs incurred in meeting demand and reserves. Environmental costs are not internalised. A cap is placed on the annual amount of CO2.
2018/11/07

8. Assumptions

9. Input Data As per IRP2010 (updated where required) Demand Forecast
Eskom and CSIR
Reserves Requirements
Eskom System Operator
New build options
EPRI
CSP plant (Solar 1)
Owner’s Engineer, SAM and EPRI
Station commercial from 2022
Existing Plant
Eskom
DSM
Eskom IDM
2018/11/07

10. Integrated Resource Plan 2010 (IRP 2010) centrally defines the generation mix until 2030
Installed capacity
Energy mix
Total installed
Capacity in GW
Electricity supplied
in TWh per year
Re- newable
TWh's in 2030
(14%) 90 86
436 PV PV
Carbon free TWh's in 2030
(34%) 80
CSP
CSP
Wind 70
Wind
Hydro
Hydro 60
Nuclear
Nuclear
255
OCGT (Diesel) 50
OCGT (Diesel) 42
CCGT (Gas) 40
CCGT (Gas) 30
Coal 20
Coal 10
2010
2015
2020
2025
2030
Share re-newables
2010
2015
2020
2025
2030 5%
14%
~ 95%
??%
CO2 intensity
912 g/kWh
600 g/kWh
-34%
Notes: Pumped storage capacity of 1,4 GW in 2010 and 2,7 GW in 2030 is not included since it is a net energy user
Source: Integrated Resource Plan 2010, as promulgated in 2011; Eskom EPMD

11. Study

12. Models Models: SAM and Plexos
SAM Convert solar irradiation to thermal energy available from Receiver (on an hourly basis)
Plexos System optimisation by minimising total cost subject to constraints. Hourly chronological modeling. Monte Carlo approach for uncertainties.
2018/11/07

13. Options CSP parameters Solar Multiple (SM) – 1,0 to 3,5
CSP Storage – 1 to 12 hours
System Parameters
IRP2010 Policy Adjusted Plan
Most significant impact for this analysis will be system adequacy
Excess supply will decrease optimal CSP storage
Supply shortage will increase optimal CSP storage
Only IRP2010 Plan studied = adequate system
2018/11/07

14. Results

15. Load Factor (Capacity Factor)
CSP : Load Factor vs. Storage
Load Factor = Energy Sent-out in period (year) / (Sent-out Capacity x Hours in period (year))
Sent-out means as measured on the HV-side of the generator transformer (entry into the HV substation)
2018/11/07

16. Incremental Value and Cost
Incremental Value or Incremental Cost vs. Incremental Storage
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17. Total System Cost
Total System Cost vs. Storage
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18. Levelised Cost of Energy (LCOE)
LCOE calculated from:
Plant CAPEX, O&M and Running costs used in the study
Optimal storage, with associated annual generation, as determined in the study
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19. Hourly Profiles
Summer (four days)
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20. Hourly Profiles
Winter (four days)
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21. Optimal Storage (hours)
Conclusions
A CSP Load Factor of > 60% can only be reached at Solar Multiples > 3,0 and storage in excess of 8 hours.
CSP’s optimum storage capability, when using as value the benefit gained from forming part of the South African system, has been determined as:
Based on the system analysis of SM up to 3,5 and number of Storage hours up to 12 the system optimal is reached at SM between 2,5 and 3,0 and Storage of between 9 and 12 hours.
The CSP LCOE can be reduced to 65% of the LCOE at a base of SM = 1, when developed and operated at the system optimal point.
The increased daily summer solar energy (compared to winter) dovetails well with the higher load factor requirement in summer due to the flatter system demand profile in summer. SM
1,0
1,5
2,0
2,5
3,0
3,5
Optimal Storage (hours) 3 5
7,5 11
>12
2018/11/07

22. Thank you