Reducing Wind Curtailment through
Transmission Expansion in a Wind Vision Future
Jennie Jorgenson, Trieu Mai, Gregory Brinkman
Windpower 2017
May 23, 2017
Presentation Overview
•
•
•
•
•
Wind Vision Study Background
Objectives
Methodology
Results
Conclusions
2
Wind Vision Study Background
Current Project builds on the Wind Vision study
• The 2015 DOE Wind Vision study showed the potential for U.S. wind energy to
provide substantial health, environmental, and economic benefits.
In the Wind Vision
Study Scenario wind
power serves 35% of
U.S. electricity
consumption in 2050.
4
Regional Wind Penetration Drives Integration and Transmission Needs in the Wind
Vision Study Scenario
2050 regional wind penetration
Incremental Transmission needs (2013-2050)
• While all regions contribute, annual wind penetration varies by region, with some
exceeding 45% by 2050, particularly for Western & Central regions
• Transmission expansion was found to be one of the options to support increased
wind penetration
5
Objectives
Expand on the work of the Wind Vision Study
Electric systems impacts, including grid integration and transmission
challenges, are generally perceived to be manageable
• Use high fidelity modeling to assess the operational feasibility of a Wind
Vision future in the western United States
o
o
Identify potential reliability issues
Identify potential integration issues
• Assess the value of transmission expansion—in reducing renewable energy
curtailment, generation costs, and carbon dioxide emissions—under this high
wind future
7
Methodology
Modeling the Electric Power Grid – why is it so difficult?
• A very large rotating machine
spinning at 60 Hz (here in the US)
• Rules:
o Supply must equal demand
9
Modeling the Electric Power Grid – why is it so difficult?
• A very large rotating machine
spinning at 60 Hz (here in the US)
• Rules:
Supply must equal demand
Demand changes every instant
(supply might too!)
o Must maintain system reliability
(or, be prepared for bad things to
happen)
o Subject to the laws of physics
o
o
10
Modeling the Electric Power Grid – why is it so difficult?
• A very large rotating machine
spinning at 60 Hz (here in the US)
• Rules:
Supply must equal demand
Demand changes every instant
(supply might too!)
o Must maintain system reliability
(or, be prepared for bad things to
happen)
o Subject to the laws of physics
o
o
• Renewable energy can complicate
things further
o
o
Weather-dependent
Can require faster response from
the rest of the generating fleet
11
Modeling the operation of the electric power grid
• Use a commercially-available tool for grid
simulation (PLEXOS)
• Grid database from a number of recent
studies
o
o
o
Western Wind and Solar Integration Study
California Low Carbon Grid Study
Renewable Electricity Futures Sub-hourly
Study
• Starting transmission reflecting 2030
anticipated transmission system
• Align wind, solar, and load with the Wind
Vision Central Study Scenario in 2050 for
the Western U.S.: 37% wind and 12% solar
(available energy)
West-wide: 37% wind and 12% solar
(available energy)
12
Results
Reference case: 2050 wind levels with no transmission buildout
• Grid simulations find no hours of unmet load or unserved reserves in
any scenario
• While these metrics do not guarantee reliability, they do help reinforce
the Wind Vision conclusion that integration is “manageable”
14
Reference case: 2050 wind levels with no transmission buildout
• In the Reference scenario (which includes 2050 wind buildout with 2030
transmission buildout), annual RE curtailment estimated to be 15.5%
o
o
Curtailment is found in all seasons, but primarily in the non-summer
months
Most of the curtailment found in the most-eastern states of the Western
Interconnection (MT, NM, WY)
15
Bounding sensitivities suggest that curtailment is primarily caused by transmission
congestion
• 2 bounding sensitivities to Reference (no transmission buildout) Case:
o
o
“Retirements” scenario includes a more flexible generator fleet by removing
all coal units
“Copper Sheet” scenario removes all transmission constraints
Scenario
Annual
Curtailment (%)
Reference
Retirements
Copper Sheet
15.5
14.9
0.5
16
Adding transmission to the reference scenario in three additive buildouts
Transmission 1 = 10 GW
Transmission 2 = 18 GW
Transmission 3 = 21 GW
17
A relatively small amount of transmission can reduce curtailment substantially, by
about half
• 3 transmission buildout
scenarios modeled to
estimate the value of
transmission under a high
wind future
o
Transmission buildout scenarios
are increasingly speculative
• Transmission 1 = actual
proposed projects only (see
map)
o
Total 10,500 MW
• Reduces curtailment in half
(15.5% to 7.8%)
18
Further transmission buildout continues to reduces curtailment
Transmission 3: total of
21,500 MW
3 GW Capacity
Curtailment to 4.4%
Transmission 2: total of
18,500 MW
8 GW Capacity
Curtailment to 6.2%
19
Further transmission buildout continues to reduces curtailment, but with diminishing
returns
20
Estimated production cost – primarily fuel cost – savings through curtailment
reduction enabled by transmission
Total generation cost =
fuel costs
Scenario
Reference
Transmission 1
Transmission 2
Transmission 3
Copper Sheet
+ start and shutdown costs + variable operating and maintenance costs
Savings from
Reference
($B/yr)
2.3
2.6
3.4
5.3
Savings from
Reference – High
Gas Price ($B/yr)
2.8
3.2
4.2
6.7
Savings from
Reference – Low Gas
Price ($B/yr)
1.8
2.1
2.6
3.9
Reported costs from table do not include capital costs for wind, other generators, or transmission
21
The transmission buildout from the Transmission 1 scenario estimated to yield a
simple payback of between 4 and 6 years
• Annual operational savings of $1.8-2.8 billion can be compared with reported
transmission capital costs of $10.1 billion  simple payback of ~4-6 years
(4.4 years in the central case)
Transmission 1:
• This result suggests a strong economic case for transmission, but important
caveats to consider:
Estimated transmission costs are based on reported numbers; actual costs may differ
o This simple payback analysis excludes the capital cost for other infrastructure, including
new wind capacity (see Wind Vision study for this broader assessment)
o Excludes other benefits associated with transmission, e.g., reduced firm capacity needs
o Does not consider numerous other considerations around transmission expansion,
including cost and savings allocations
o
10 GW
Curtailment by half
Gen costs ($2B/yr)
• Other transmission expansion scenarios (Transmission 2&3) are estimated to
have greater potential production cost benefits, but would also have higher
capital costs
22
Conclusions
Key Findings
• Effective power systems operation can be achieved with wind penetrations greater
than 35%.
This finding helps affirm conclusions from the Wind Vision study that variability is manageable and the grid
will be operable under a high renewable energy future.
o High-resolution nodal modeling found no hours of unmet load or unserved reserves. Although this confirms
some aspects of grid reliability, this is not a full reliability study, which would include analysis of dynamic
stability and frequency response.
o Transmission expansion will play a vital role in allowing for efficient usage of renewable resources.
o
24
Key Findings
Renewable curtailment can be mitigated by transmission expansion. Reducing
curtailment also effectively reduces generation costs and carbon dioxide emissions.
If transmission is not build to support new
wind generation in the western United
States, significant renewable energy
curtailment (15.5%) could be an issue.
o Curtailment can be reduced by about half
(to 7.8%) based only on proposed
transmission projects
o Further transmission buildout continues to
reduce curtailment and generation costs but
with diminishing
o
25
Thank you.
Publication: http://www.nrel.gov/docs/fy17osti/67240.pdf
NREL Grid Integration Webinar series: http://www.nrel.gov/esi/gridintegration-webinars.html
Authors:
[email protected]
[email protected]
[email protected]
26
Additional Information
Wind Penetration By State
State
Offshore Wind
(MW)
Offshore Wind
(Annual TWh)
Land-Based
Wind (MW)
Land-Based Wind
(Annual TWh)
Arizona
-
-
5,050
13.4
California
6,510
22.0
13,500
Colorado
-
-
Idaho
-
Montana
Solar PV Generation
(Annual TWh)
Load (Annual
TWh)
36.8
15.0
66.6
118
410
9,360
30.5
9.59
63.2
-
3,000
8.05
-
-
20,900
67.6
1.22
0.669
28.3
17.9
Nevada
-
-
3,080
8.78
New Mexico
-
-
9,120
31.0
7.26
4.92
49.3
33.6
Oregon
Utah
838
-
3.45
-
8,540
1,610
25.1
4.62
Washington
2,090
9.47
8,337
21.9
4.08
5.06
5.25
91.2
46.6
115
Wyoming
-
-
24,400
91.1
0.808
57.3
Total
9,440
35.0
107,000
339
120
1,030
28
Summary results
Scenario
Reference
Transmission 1
Transmission 2
Transmission 3
Copper Sheet
Total Generation
Cost ($B/yr)
19.6
17.3
16.9
16.2
14.3
Cost Savings
compared to
Reference ($B/yr)
2.3
2.6
3.4
5.3
Annual CO2
(MMT)
308
289
281
280
293
CO2 Savings
compared to
Reference (MMT)
19
27
28
15
Annual
Curtailment (%)
16%
7.8%
6.2%
4.4%
0.5%
29
The PLEXOS results begin to confirm and expand on the original Wind Vision study
scenario
Wind Vision ReEDS results are most consistent with Transmission 3
o Curtailment: 4.4% vs. 3% (Wind Vision ReEDS)
o Western transmission (2030-2050) expansion: 21,500 MW vs. 23,000 MW (Wind Vision ReEDS)
30