Achieving)50)percent)renewable) electricityinCalifornia:) … · 2019-10-10 ·...
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Achieving 50 percent renewable electricity in California: The role of nonfossil flexibility in a cleaner electricity grid Jimmy Nelson, Ph.D. Energy Modeler [email protected] Laura Wisland Senior Energy Analyst [email protected] August 2015
Transcript of Achieving)50)percent)renewable) electricityinCalifornia:) … · 2019-10-10 ·...
Achieving 50 percent renewable electricity in California:
The role of non-‐fossil flexibility in a cleaner electricity grid
Jimmy Nelson, Ph.D. Energy Modeler
Laura Wisland Senior Energy Analyst [email protected]
August 2015
Full report available at: www.ucsusa.org/California50RPSanalysis
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“Curtailment is a reducOon in the output of a generator from what it could otherwise produce
given available resources”
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• Curtailment is a default opOon for maintaining reliability when an electricity grid relies more heavily on renewable sources of power
• Curtailment can be expensive because most renewables have low or zero marginal cost
• In limited quanOOes, curtailment can make important contribuOons to grid operaOonal flexibility, reducing the need to make other investments in flexibility
Source: Bird, L., J. Cochran, and X. Wang. 2014. Wind and solar energy curtailment: Experience and pracOces in the United States. Golden, CO: NaOonal Renewable Energy Laboratory. NREL/TP-‐6A20-‐60983. Online at hcp://www.nrel.gov/docs/fy14osO/60983.pdf.
Avoid coincident gas generation and renewable
curtailment
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The UCS “Duck Chart”
5 Fact Sheet: Renewables and Reliability, Union of Concerned ScienOsts, March 2015. Available at: hcp://www.ucsusa.org/sites/default/files/acach/2015/03/california-‐renewables-‐and-‐reliability.pdf
It would be very difficult to meet long-‐term climate goals
if gas is online when renewables are being
curtailed
Williams, J.H., et al., 2012. The technology path to deep greenhouse gas emissions cuts by 2050: the pivotal role of electricity. Science 335, 2012, 53-‐59. 6
Modeling
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Acknowledgements
• Ryan Jones, Arne Olson, and Energy and Environmental Economics (E3) • Hourly renewable, reserve, outage,
and demand data • ProducOon cost model framework • Discussions
• UCS for support, fellowship, and discussions
• NREL for discussions
• Energy Exemplar / PLEXOS for sojware support
• Report reviewers 8
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• Renewables Porkolio Standard (RPS) target: • 33%, 40%, 50%
• Geographic scope: the California Independent System Operator (CAISO) footprint • ~80% of California
• Timeframe: 2024 • Economy-‐wide decarbonizaOon might necessitate very
quick renewable deployment • Results relevant to 2030 50% RPS policy discussion
• Modeling tool: PLEXOS producOon cost model
• Focuses on electricity operaOons • NOT an investment model
Scope of analysis
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What our analysis does and does not address Our analysis does: Our analysis does not:
Focus on the year 2024 Simulate years other than 2024
Use industry standard sojware to simulate the CAISO electricity system
Simulate other sectors of the economy
Include electricity demand from 2 million electric vehicles within the CAISO footprint
Determine an opOmal amount of vehicle electrificaOon
Include a diverse porkolio of renewables OpOmize a porkolio of renewables or focus on a single renewable technology
Simulate detailed grid operaOons and constraints on generators and resources inside the CAISO footprint
Simulate detailed grid operaOons and constraints on generators and resources outside the CAISO footprint
Include generaOon requirements in specific regions inside the CAISO footprint
Model transmission constraints inside the CAISO footprint
Explore a variety of ways to reduce renewable curtailment
Find an opOmal amount of renewable curtailment or grid flexibility
QuanOfy renewable curtailment, producOon costs, and GHG emissions from electricity producOon
QuanOfy capital and fixed costs of renewable generators or addiOonal grid flexibility
QuanOfy shorkalls in generaOon capacity and reserves
Perform an analysis of system capacity need or loss of load expectaOon
A diverse porkolio of renewables is simulated
• Heavily weighted towards in-‐state renewables • Behind-‐the-‐meter photovoltaics (PV) don’t directly count
towards RPS 11
0
20
40
60
80
100
120
33% RPS 40% RPS 50% RPS
Electricity
Produ
c>on
(TWh/Yr) PV Behind-‐the-‐Meter
PV Large Out-‐of-‐State PV Large In-‐State Solar Thermal Wind Out-‐of-‐State Wind In-‐State Small Hydroelectric Biogas Biomass Geothermal
As the RPS is increased…
[without addiOonal operaOonal flexibility]
GHG Emissions
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0
10
20
30
40
50
60
33 40 50 RPS Target (%)
CO2 E
mission
s (MMTC
O2/Yr)
Note: producOon costs do not include capital and maintenance costs, and are therefore only one important part of the total electricity cost
ProducOon Costs
0 1 2 3 4 5 6 7
33 40 50 RPS Target (%)
Prod
uc>o
n Co
sts ($B
/Yr)
Renewable Curtailment
4.8
0
1
2
3
4
5
6
33 40 50
RPS Target (%)
% Curtailm
ent
OperaOonal constraints keep gas online during hours that experience renewable curtailment
0 2 4 6 8 10 12 14 16 18 20 22 -‐20 -‐15 -‐10 -‐5 0 5 10 15 20 25 30 35
Gen
era>
on (G
Wh)
Hour of Day
Example day depicted here is a near worst-‐case weekend day in May
Renewable Storage Supply Exports Gas Peaker Gas Combined Cycle Hydroelectric Combined Heat and Power Nuclear
Adjusted Input
Supply
Demand
Renewable Curtailment Storage Demand Exports
Downward Balancing
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Coincident gas generaOon and renewable curtailment
Renewables can provide some electricity during Omes of greatest need for system capacity
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0
0.5
1
1.5
2
2.5
3
3.5 14
15
16
17
18
19
15
16
17
18
19
15
16
17
18
19
16
17
18
19
16
17
17
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17
17
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Reserve ShorPall (GW) 33% RPS 40% RPS 50%
RPS Base
Hour of Day
• However, even at a 50 percent RPS, renewables cannot produce enough power to ensure a reliable electricity system during some peak periods, resulOng in reserve shorkalls
• Our study suggests that the projected 2024 CAISO fleet of natural gas power plants will be important in ensuring that the grid has enough capacity to meet demand during peak periods
Non-‐Spinning Load Following Up
July July Sept Sept Sept
Reliability requirements cause renewable curtailment
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4.8
1.5 1.0
0
1
2
3
4
5
6
50% RPS Remove Downward Reserves
Remove Downward Reserves and Regional
GeneraOon Requirements
Curtailm
ent (%)
50% RPS Base
EssenOal reliability services needed in grid operaOons
[But some reliability requirements cause curtailment at a 50% RPS]
Load Following and Regula>on
DOWN
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Load following bridges between hourly and five minute schedules
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Load following up
Five-minute schedule
Load following down
Hourly schedule
Five minutes
Net
dem
and
(MW
)
One hour
Figure based on: Makarov, Y. V., et al., 2009. OperaOonal Impacts of Wind GeneraOon on California Power Systems.
IEEE Transac/ons on Power Systems 24 (2), 2009, 1039-‐1050.
RegulaOon bridges between five minute schedules and actual generaOon
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One hour
Five minutes
Regulation up
Five-minute schedule
Actual generation Regulation down
Net
dem
and
(MW
)
Figure based on: Makarov, Y. V., et al., 2009. OperaOonal Impacts of Wind GeneraOon on California Power Systems.
IEEE Transac/ons on Power Systems 24 (2), 2009, 1039-‐1050.
Regional generaOon requirements are a proxy for many essenOal reliability services
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² voltage support and reacOve power ² inerOa and primary frequency response/governor response ² local and system-‐wide requirements for operaOng reserves ² transmission congesOon ² transmission conOngencies
Grid planners and operators should encourage non-‐fossil resources (including renewable generators) to provide essenOal reliability services
These reliability consideraOons could cause coincident renewable curtailment and gas generaOon:
Increasing operaOonal flexibility at a 50% RPS:
What works and what doesn’t
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[3] Add non-‐generaOon flexibility: Storage
Advanced Demand Response Exports
[2] Increase natural gas power plant
fleet flexibility
[1] Operate renewables more flexibly
We modeled three different flexibility strategies
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Strategy [1]: Operating renewables flexibly is particularly effective
0 1 2 3 4 5 6
50% RPS Renewables Provide Reserves
Curtailm
ent (%)
Hourly Curtailment
Sub-‐Hourly Curtailment
4.8
2.7
50% RPS Base
• Curtailment: nimble is much becer than blocky • Renewables should be incenOvized to parOcipate in CAISO markets
and to install or uOlize control equipment
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Renewables frequently provide downward reserves
Online reserves: Load following, regulaOon, and spinning
-‐4 -‐3 -‐2 -‐1 0 1 2 3 4 5
50% RPS Base
Renewables Provide Reserves
Average Online Re
serve
Provision (GW)
Renewable Upward Storage Upward Hydro Upward
Gas Upward
• Renewables don’t have to be pre-‐curtailed to provide downward reserves
Upw
ard
Downw
ard
• More analysis needed on cost tradeoffs
Strategy [2]: Non-‐generaOon flexibility reduces curtailment and GHG emissions
AddiOonal Non-‐GeneraOon Flexibility (GW) = storage + advanced demand response + exports
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41.1 38.8 37.6 37.0
0
10
20
30
40
50
0
1
2
3
4
5
6
0 3 6 9
% Curtailm
ent
CO2 E
mission
s (M
MTC
O2/Yr)
Reserves from non-fossil resources are valuable
-‐4 -‐3 -‐2 -‐1 0 1 2 3 4 5
0 3 6 9
Average Online Re
serve
Provision (GW)
Addi>onal Non-‐Genera>on Flexibility (GW)
Demand Response Upward
Storage Upward
Hydro Upward
Gas Upward
% Non-‐Fossil
• Downward reserves are parOcularly valuable 25
Upw
ard
Downw
ard
37% 56% 67% 75%
Strategy [3]: Gas power plant flexibility has important limits
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Gas fleet changes in the Flexible Gas run: • Double ramp rate • Half minimum
power level • 1 hour start and
stop Omes • 2 hour minimum
upOme and downOme
• Providing some reliability services with gas requires electricity producOon, which “crowds out” renewables
4.8 4.7
3.2 3.0
0
1
2
3
4
5
6
Default Gas Flexibility
Double Ramp Rate
Combined Cycle Half Minimum Power Level
Flexible Gas
% Curtailm
ent
• Duck Chart: “belly” is much more important than the “neck”
Renewable flexibility competes with gas flexibility
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• When renewables can provide reserves, the amount of operaOonal flexibility on the grid increases. Consequently, the amount of curtailment that can be avoided by increasing the flexibility of natural gas power plants decreases
4.8 4.7
3.2 3.0 2.7 2.6 2.1 2.0
0
1
2
3
4
5
6
Default Gas Flexibility
Double Ramp Rate
CCGT Half Minimum Power Level
Flexible Gas
% Curtailm
ent
Without Renewable Reserves With Renewable Reserves
Non-‐Fossil SoluOons: • Renewables can provide
reserves • 1 GW addiOonal electricity
storage • 1 GW advanced demand
response • 1 GW net exports allowed
OperaOonal flexibility: Non-‐fossil can go further than gas
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39.0 41.1 37.4
0 10 20 30 40 50
Flexible Gas
50% RPS Non-‐Fossil SoluOons
CO2 E
mission
s (M
MTC
O2 /Yr)
3.0
4.8
1.1
0 1 2 3 4 5 6
Flexible Gas
50% RPS Non-‐Fossil SoluOons
% Curtailm
ent
50% RPS Base
50% RPS Base
Non-‐fossil soluOons can turn gas down or off when ample renewable energy is available
Example day depicted here is a near worst-‐case weekend day in May
Renewable Storage Supply Demand Response Supply Gas Peaker Gas Combined Cycle Hydroelectric Combined Heat and Power Nuclear
Adjusted Input
Supply
Demand
Renewable Curtailment Storage Demand Demand Response Demand Exports
Downward Balancing
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0 2 4 6 8 10 12 14 16 18 20 22 -‐20 -‐15 -‐10 -‐5 0 5 10 15 20 25 30 35
Gen
era>
on (G
Wh)
Hour of Day
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33% RPS 50% RPS
Renewable curtailment
Renewable dispatchability
At a 50% RPS, renewables should help to integrate themselves by being dispatchable during criOcal Omes
• Increasing the RPS from 33% to 50% reduces electricity GHG emissions by 22 - 27%
• Coincident gas generation and renewable curtailment should be avoided
• Reliability requirements cause renewable curtailment
• Operating renewables flexibly is particularly effective
• Non-generation flexibility can reduce GHG emissions
• Natural gas power plant flexibility has important limits
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Key findings
