The document discusses the concept of power system flexibility, highlighting its importance in adapting electricity generation and consumption to maintain system stability, especially with the integration of variable renewable energy sources (VRES). It outlines the need for new flexibility options due to the increasing variability and uncertainty introduced by VRES, as well as categorizing existing and new flexibility resources. Conclusions stress the necessity for improved control systems, market changes, and incentives for demand management to address the emerging flexibility gap in high-VRES systems.

1. Dr. G. Papaefthymiou, K. Grave
22/05/2014
Can we achieve 100%
renewables? Flexibility options
in the electricity system
Webinar Leonardo Energy

2. © ECOFYS | |
Overview
1. Definition of power system flexibility
2. Need for Flexibility
3. Overview of Flexibility Options
4. Mapping of Flexibility Options
5. Conclusions and recommendations
22/05/2014 Dr. G. Papaefthymiou2

3. © ECOFYS | |
Overview
1. Definition of power system flexibility
2. Need for Flexibility
3. Overview of Flexibility Options
4. Mapping of Flexibility Options
5. Conclusions and recommendations
22/05/2014 Dr. G. Papaefthymiou3

4. © ECOFYS | |© ECOFYS | |
The key physical components of flexibility:
22/05/20144
Demand
Supply
Network
System
System
Demand:
partly
controllable
Network:
ability for
spatial
matching
System:
operational
rules
Supply:
controllable or
intermittent
(RES)
Dr. G. Papaefthymiou
> Power systems are designed to ensure a spatial and temporal
balancing of generation and consumption at all times.

5. © ECOFYS | |© ECOFYS | |
Definition of Power System Flexibility
> Power system flexibility represents the extent to which a power
system can adapt electricity generation and consumption as needed to
maintain system stability in a cost-effective manner.
> Flexibility is the ability of a power system to maintain continuous
service in the face of rapid and large swings in supply or demand.
> Measures of flexibility:
– Ramp rates, minimum up/down times, and start-up/shut-down
times are commonly used indicators of flexibility, measured as MW
available for ramping up and down over time
> Role of power networks:
– Key enablers of flexibility, since they define the spatial dimension
of balancing and thus to which extent flexibility resources can be
shared between adjacent areas.
22/05/2014 Name5

6. © ECOFYS | |© ECOFYS | |
Overview
1. Definition of power system flexibility
2. Need for Flexibility
3. Overview of Flexibility Options
4. Mapping of Flexibility Options
5. Conclusions and recommendations
22/05/2014 Dr. G. Papaefthymiou6

7. © ECOFYS | |© ECOFYS | |
Daily patterns of net electricity demand for
different VRES penetration levels
22/05/20147
-20
0
20
40
60
80
SystemNetDemand(GW)
No RES
Hours
Dr. G. Papaefthymiou

8. © ECOFYS | |© ECOFYS | |
Daily patterns of net electricity demand for
different VRES penetration levels
22/05/20148
-20
0
20
40
60
80
SystemNetDemand(GW)
No RES 20%
Hours
Dr. G. Papaefthymiou

9. © ECOFYS | |© ECOFYS | |
Daily patterns of net electricity demand for
different VRES penetration levels
22/05/20149
-20
0
20
40
60
80
SystemNetDemand(GW)
No RES 20% 40%
Hours
Dr. G. Papaefthymiou

10. © ECOFYS | |© ECOFYS | |
Daily patterns of net electricity demand for
different VRES penetration levels
22/05/201410
-20
0
20
40
60
80
SystemNetDemand(GW)
No RES 20% 40% 60%
Hours
Dr. G. Papaefthymiou

11. © ECOFYS | |© ECOFYS | |
Daily patterns of net electricity demand for
different VRES penetration levels
22/05/201411
-20
0
20
40
60
80
SystemNetDemand(GW)
No RES 20% 40% 60% 80%
Hours
Dr. G. Papaefthymiou

12. © ECOFYS | |© ECOFYS | |
Daily patterns of net electricity demand for
different VRES penetration levels
22/05/201412
-20
0
20
40
60
80
SystemNetDemand(GW)
No RES 80%
Hours
Dr. G. Papaefthymiou

13. © ECOFYS | |© ECOFYS | |
Hourly ramping range of net electricity demand
for different VRES penetration levels
22/05/201413 Dr. G. Papaefthymiou
-25
-20
-15
-10
-5
0
5
10
15
20
25
SystemNetDemandHourlyRamps(GW/h)
No RES 20% 40% 60% 80%
Hours

14. © ECOFYS | |© ECOFYS | |22/05/201414
-40
-20
0
20
40
60
80
100
120
140
160
180
200
-20
0
20
40
60
80
100
Spotprice[€/MWh]
Generation/Demand[GW]
Kernenergie Braunkohle Kohle Erdgas
Öl Andere Pumpspeicher Laufwasser
Saisonspeicher Wind Solar Unbekannt
Monday Tuesday Wednesday Thursday Friday Saturday Sunday
Nuclear Lignite
Oil
Hydro storage
Other
Natural Gas
Pump storage
unknown
Run of River
Export
Wholesale
price
Coal
Demand
Oversupply events already happen
Oversupply event:
High RES
Low Demand
CGs at their limit
Source: EEX, ENTSO-E,
the example shows
German ex-post data
for one week in
February 2011
Dr. G. Papaefthymiou

15. © ECOFYS | |© ECOFYS | |
Dynamic range of net electricity demand for
different VRES penetration levels
22/05/201415
-60
-40
-20
0
20
40
60
80
SystemNetDemand(GW)
No RES 20% 40% 60% 80%
Hours
BASELOAD
MIDLOAD
PEAK LOAD
Dr. G. Papaefthymiou

16. © ECOFYS | |© ECOFYS | |
Need for flexibility
> Traditional power systems:
Need for flexibility because of demand variations and sudden loss
of generation units
– variability of demand
– uncertainty of supply
• Flexibility provided by supply side (power plant fleet)
> Introduction of variable RES:
– Increasing the need for flexibility: Increase in variability
and uncertainty in the supply side
– Reduction of the flexibility potential: VRES displace part
of the conventional generation capacity (impact on portfolios
and operational)
• New flexibility options are needed
22/05/201416 Dr. G. Papaefthymiou

17. © ECOFYS | |© ECOFYS | |
Impacts of VRES on the flexibility timeline
22/05/201417
Long term planning
flexibility
Does my system have sufficient
resources to manage
operational variability?
Operational planning
flexibility:
How many flexibility resources
should be committed to ensure
secure operation?
Operational
Flexibility:
Which are the
most
economic
resources?
Dr. G. Papaefthymiou
Source: H. Holttinen, A. Tuohy, M. Milligan, E. Lannoye, V. Silva, S. Muller, L. Soder, The flexibility workout: Managing variable resources and assessing the need for
power system modification, IEEE Power & Energy Magazine, November/December 2013

18. © ECOFYS | |© ECOFYS | |
Overview
1. Definition of power system flexibility
2. Need for Flexibility
3. Overview of Flexibility Options
4. Mapping of Flexibility Options
5. Conclusions and recommendations
22/05/2014 Dr. G. Papaefthymiou18

19. © ECOFYS | |© ECOFYS | |
Categorisation of flexibility options
System
Energy
Storage
Supply
Net-
work
Demand
22/05/201419 Dr. G. Papaefthymiou

20. © ECOFYS | |© ECOFYS | |
Overview of flexibility options
22/05/201420
Supply
Demand
Energy
Storage
System
Net-
work
1. Flex Coal, 2. Gas
3. Oil, 4. Biogas,
5. CHP, 6. Nuclear
7. VRES
8. Pump storage,
9. (AA-)CAES
10. Flywheels
11. Batteries
12 Hydrogen (Power to Gas)
13. Demand Response
- Energy intensive industries
- Services
- Smart applications
14. Electric vehicles
15. Heat pumps
16. Resistance heating
17. Network expansion (Installation of lines)
- Add transmission capacity (HVAC /HVDC)
- Increase meshing, alleviate congestions
18. Power flow control (“smart“ devices)
- Flow control devices PST, FACTS, HVDC
19. Market Rules
20. Market integration:
- Expansion of markets
- Expansion of control zones
Dr. G. Papaefthymiou

21. © ECOFYS | |© ECOFYS | |
Overview
1. Definition of power system flexibility
2. Need for Flexibility
3. Overview of Flexibility Options
4. Mapping of Flexibility Options
5. Conclusions and recommendations
22/05/2014 Dr. G. Papaefthymiou21

22. © ECOFYS | |© ECOFYS | |
Mapping of flexibility options
22/05/201422
Short term flexibility Long term flexibility
Lower ST/MT flex potential, unit commitment constraints
Mid term flexibility
SUPPLY
Coal
Lower ST/MT flex potential, unit commitment constraints
Lignite
Lower ST flex potential, unit commitment constraints
CCGT Flex mode can be enhanced
Flexible – high variable costsOCGT
High variable costs, limited local supplyBiogas
Stochastic behaviour – Perceptual and political concerns(waste of ´free´ energy)VRES APC
Flexible –high variable costs, emissionsICE
Nuclear
Constrained due to primary operationLarge CHP
Constrained due to primary operationMicro CHP
DEMAND
Industrial DR High potential – flexibility constrained by primary industrial process
Small scale DR High potential – flexibility depends on user behaviour
Electric Vehicles
Heat pumps
Electric heating
STORAGE
Pumped Hydro Low potential for extra expansion
AA-CAES Low efficiency, restricted potential for expansion
Very high investment costsFlywheels
Technology development needed for efficiency improvementBatteries
Low efficiency – option for seasonal storagePower to gas
Constrained by transport sector/primary operation
Constrained by heat sector/primary operation
Constrained by heat sector, low efficiency
Red options are small-scale distributed technologies – communication & control infrasturcture key enabler
Bold/Underscore options are mature technologies – maturity of most demand and storage options is low
Dr. G. Papaefthymiou

23. © ECOFYS | |© ECOFYS | |
Market barriers
22/05/201423 Dr. G. Papaefthymiou
-20000
0
20000
40000
60000
80000
100000
120000
1 5001
Ohne EE
20% EE
40% EE
0
00000
00000
00000
00000
00000
00000
00000
00000
0%
2%
4%
6%
7%
9%
11%
13%
15%
17%
19%
20%
22%
24%
26%
28%
30%
32%
34%
35%
37%
39%
41%
43%
45%
47%
48%
50%
52%
54%
56%
58%
60%
61%
63%
65%
67%
69%
71%
73%
74%
76%
78%
80%
82%
84%
86%
87%
89%
91%
93%
95%
97%
99%
Grundlasttechnologie
Mittellasttechnologie
Spitzenlasttechnologie
Costs[€/kWa]
time [h] 87600
87600
Demand[GW]
0% VRES 40% VRES
Peak load technology
Middle load technology
Base load technology
20% VRES
Residual load curve shifts
because of additional VRES
time [h]
Base load technology
Middle load technology
Peak load technology
0% VRES
20% VRES
40% VRES
> VRES have low marginal costs
– Downward pressure to electricity prices,
– Reduced full-load hours for conventional units
> Still, conventional peak power plants are needed to
meet load in times of low VRES generation.
> How to incentivize flexibility?
– Supply options are driven by market prices
– Flexibility options are driven by market price
variability (spreads)

24. © ECOFYS | |© ECOFYS | |
Overview
1. Definition of power system flexibility
2. Need for Flexibility
3. Overview of Flexibility Options
4. Mapping of Flexibility Options
5. Conclusions and recommendations
22/05/2014 Dr. G. Papaefthymiou24

25. © ECOFYS | |© ECOFYS | |
The Flexibility Gap
22/05/201425 Dr. G. Papaefthymiou
Low High
Existing Supply Flex New Supply Flex
Flexibility
VRES
FlexibilityGap
Storage Flex
Demand Flex

26. © ECOFYS | |© ECOFYS | |
Conclusions and recommendations
22/05/201426 Dr. G. Papaefthymiou
> A flexibility gap is created by the shift towards high-VRES
systems
> New flexibility options in demand and storage require control and
communication infrastructure
> VRES control is unavoidable for higher RES shares
> Changing the market is needed for reducing the flexibility gap
> Incentives and systems for demand management are needed
> Extending the market size is a no regret solution

27. © ECOFYS | |22/05/201427
Questions?
> Dr. Georgios Papaefthymiou
Ecofys Germany GmbH
Am Karlsbad 11
10785 Berlin
Germany
E: g.papaefthymiou@ecofys.com
I: www.ecofys.com
Dr. G. Papaefthymiou