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© OECD/IEA 2015
Flexible Power Systems to Integrate Large Shares of Renewables The Value of Interconnections
IEA-SGCC Dialogue on Global Energy Interconnection
“Global Energy Interconnection- Smart Grids and Beyond” 21-22 July 2015, Beijing, China
Simon Müller Senior Analyst - Renewable Energy Division
© OECD/IEA 2014
Interaction is key
Properties of variable renewable energy (VRE)
Flexibility of other power system components
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Variable
Uncertain
Non-synchronous
Location constrained
Modularity
Low short-run cost
sec
yrs
1 km
100s km
Grids Generation
Storage Demand Side
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Power systems already deal with a vast demand variability Can use existing flexibility for VRE integration
No problem at 5% - 10%, if …
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Exceptionally high variability in Brazil, 28 June 2010
No technical or economic challenges at low shares, if basic rules are followed: Avoid uncontrolled, local ‘hot spots’ of deployment
Adapt basic operation strategies, such as using forecasts/predictions of VRE generation
Ensure that VRE power plants are state-of-the art and can stabilise the grid
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Main persistent challenge: Balancing
Note: Load data and wind data from Germany 10 to 16 November 2010, wind generation scaled, actual share 7.3%. Scaling may overestimate the impact of variability; combined effect of wind and solar may be lower, illustration only.
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0
10
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1 10 20 30 40 50 60 70 80 90 100 110 120 130 140 Hours
Net
load
(G
W)
0.0% 2.5% 5.0% 10.0% 20.0%
Larger ramps at high shares
Higher uncertainty
Larger and more pronounced changes
Illustration of net load at different VRE shares
Net load = power demand
minus VRE output
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Netload implies different utilisation for non-VRE system
Main persistent challenge: Utilisation
Note: Load data and wind data from Germany 10 to 16 November 2010, wind generation scaled, actual share 7.3%. Scaling may overestimate the impact of variability; combined effect of wind and solar may be lower, illustration only.
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0
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90
1 2 000 4 000 6 000 8 000
Net
load
(G
W)
Hours
0.0% 2.5% 5.0% 10.0% 20.0% Maximum
remains high: Scarcity
Lower minimum:
Abundance
Changed utilisation pattern
Base - load
Mid - merit
Peak
Mid - merit
Peak
Mid - merit
Base - load
-
-
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2. Make better use of
what you have
Op
eratio
ns
1. Let wind and solar play their
part
3. Take a system wide-strategic
approach to investments!
System friendly
VRE
Technology spread
Geographic spread
Design of power
plants
Three pillars of system transformation
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Investm
ents
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1) System friendly VRE deployment
Wind and solar PV can contribute to grid integration
But only if they are allowed and asked to do so!
Take a system perspective when deploying VRE
Source: adapted from Agora, 2013
Example: System friendly design of wind turbines reduces variability
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2) Better system operation
VRE forecasting
Better system operations: Dynamic system scheduling
Update schedules close to real time
Dynamic system dispatch Short dispatch intervals
Dynamic use of the grid Update interconnection schedules close to real time; sub-hourly scheduling
Reward flexible operation Make payments based on what is helpful for the system, not just MWh
Make better use of what you have already!
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0
10
20
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40
50
60
0
1
2
3
4
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8
2008 2009 2010 2011 2012
Inst
alle
d V
RE
cap
acit
y (G
W)
Res
erve
req
uir
emen
t (G
W) VRE
capacity
Upward reserves
Downward reserves
+100%
+0%
-40%
Required frequency restoration reserves in Germany
Germany has four balancing areas (historic reasons)
Reserve sharing mechanism across four areas
Reduced requirements despite rapid increase of VRE
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German hard coal plants carry most of ramping duty in Germany Lignite and nuclear ramp as well, even nuclear at some times
Ramping costs can be minimised at low cost; retrofits are possible e.g. Flexible Coal: Evolution from Baseload to Peaking Plant (NREL, 2013)
Flexibility: ask for it…. and it appears
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A sunny 1st May 2013 in Germany – actual production
Source: Fraunhofer ISE
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3) Investment in additional flexibility
Grid infrastructure
Dispatchable generation Storage
Demand side integration
Four sources of flexibility …
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-20
0
20
40
60
80
321 322 323 324 325 326 327
GW
Day of the year Wind Solar Demand Net load
Investments in system flexibility – Need for a mix of solutions
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No single resource does it all! : very suitable, :suitable, o : neutral, : unsuitable Data: Germany 2011, 3x actual wind and solar PV capacity
Abundance Flexible generation
DSI
Storage
Curtailment
Multi-day scarcity Flexible generation
DSI o
Storage
Curtailment
-20
0
20
40
60
80
33 34 35 36 37 38 39
GW
Day of the year Wind Solar Demand Net load
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Flexibility options - Transmission Where do you get inexpensive flexibility?
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Interconnection can offer low-cost flexibility
Grid infrastructure is unique, only flexibility option with a double benefit: Reduces the need for flexibility by smoothing VRE output
Increases the portfolio of available flexible resources
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Competitive Renewable Energy Zones (CREZ), Texas
Wind plants were built before completing all transmission lines
Curtailment peaked at 17% of possible annual wind energy output in 2009
Curtailment reduced to 1.6% in 2013 after implementing upgrade of system operating and expanding the grid
Transmission – Key for integration
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345 kV double-circuit upgrades identified in
CREZ transmission plan
CREZ, Texas
Source: NREL
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Policy and regulatory framework
Border = seam
Policy and regulatory framework Policies 2
3 Operational rules / Markets
Interconnectors 1
Country/ Area A
Country/ Area B
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Interconnectors: developing new lines
Transmission Line Candidates to Project of Common Interest (PCI), May 2013
1
Source: EU commission
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Policies: regulation of reliability often fragmented
North America: reliability regulation
EU: Security of supply directive (2005/89/EC) Member states are responsible for electricity security
“ Member states shall take appropriate measures to maintain a balance between the demand for electricity and the availability of generation capacity”
PJM and MISO: States covered and NERC Regions
Federal Energy Regulatory CommissionM
isso
usri
Wis
cons
in
Iow
a
Min
esot
a
Neb
rask
a
No
rth
Dak
ota
Mic
higa
n
Illin
ois
Indi
ana
Ohi
o
Tene
ssee
Kent
ucky
Vir
gini
a
Mar
ylan
d
Del
awar
e
Pe
nn
sylv
ania
New
Jese
y
National Electric Reliability Council
MRO RFCSERC/RFCRFC
MISO PJM
Federal
ISO/RTO
State
Region
2
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Markets and operations: cross-border management of scarcity and power exchanges
Commercial agreements and operational rules
Finding pricing mechanism for electricity exchanges when flows cross borders with very different market design
Facilitating dynamic operation of interconnection across different systems
Operation under tight system conditions:
Reliability standards
Disconnection of interconnectors
Prioritization of contracts
Load curtailment protocols
3
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Even if technically feasible and possible win-win: Costs possibly very high, asset utilisation important factor
Technology progress may change the picture (CSP/PV cost)
Agreement on how to share costs can be a huge challenge
Motivation for ‘transit’ countries can be very low
(Inter)Continental interconnections Example: DESERTEC concept
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Source: IEA CSP roadmap, 2010
HVDC link included in 2010 IEA Concentrating Solar Power roadmap
Source: Desertec foundation
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All countries where VRE is going mainstream should:
Optimise system and market operations
Deploy VRE in a system-friendly way to maximise their value to the overall system
Countries beginning to deploy VRE power plants (shares of up to 5% to 10% of annual generation) should:
Avoid uncontrolled local concentrations of VRE power plants (“hot spots”)
Ensure that VRE power plants can contribute to stabilising the grid when needed
Use state of the art VRE forecast techniques
Integrating wind and solar power Conclusions 1/3
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© OECD/IEA 2014
* Compound annual average growth rate 2012-20 , slow <2%, dynamic ≥2%; region average used where country data unavailable This map is without prejudice to the status of or sovereignty over any territory, to the delimitation of international frontiers and boundaries and to the name of any territory, city or area.
Transformation depends on context Conclusions 2/3
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Stable Power Systems
• Little general investment need short term
Dynamic Power Systems
• Large general investment need short term
Slow demand growth*
Dynamic demand growth*
Maximise the contribution from existing flexible assets
Decommission or mothball inflexible polluting surplus capacity to foster system transformation
Implement holistic, long-term transformation from onset
Use proper long-term planning instruments to capture VRE’s contribution at system level
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Large scale transmission links part of the solution for today’s and tomorrow’s power systems
Unique value of grid infrastructure Reduces need for flexibility
Increases availability of distant flexible resources
(Inter)continental projects often face large challenges: Building the ‘hardware’ is not enough,
harmonisation of ‘software’ can be challenging
Technology progress may change project economics: Future cost of storage? True potential of demand side?
Cost-sharing between countries can be very difficult
Will countries rely on each other for security of electricity supply
(Inter)Continental Interconnection Conclusions 3/3
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