achieving 50 percent renewable electricity in california: the role of non-fossil flexibility in...
TRANSCRIPT
Achieving 50 percent renewable electricity in California:
The role of non-fossil flexibility in cleaning the electricity grid
Jimmy Nelson, Ph.D.Energy Modeler
Avoid coincident gas generation and renewable
curtailment
2
The UCS “Duck Curve”
3Fact Sheet: Renewables and Reliability, Union of Concerned Scientists, March 2015.Available at: http://www.ucsusa.org/sites/default/files/attach/2015/03/california-renewables-and-reliability.pdf
Very difficult to meet long-term climate goals if gas is
online when renewables are available
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. 4
Modeling
5
Acknowledgements
• Ryan Jones, Arne Olson, and Energy and Environmental Economics (E3)• Hourly renewable, reserve, outage,
and demand data• Production cost model framework• Discussions
• UCS for support, fellowship, and discussions
• NREL for discussions
• Energy Exemplar / PLEXOS for software support
• Report reviewers6
7
• RPS target: 33%, 40%, 50%
• Geographic scope: the CAISO footprint• ~80% of California
• Timeframe: 2024• Economy-wide decarbonization might necessitate very quick
renewable deployment• Results relevant to 2030 50% RPS policy discussion
• Modeling tool: PLEXOS production cost model• Focuses on electricity operations• NOT an investment model
Scope of analysis
A diverse portfolio of renewables is simulated
• Heavily weighted towards in-state renewables• Behind-the-meter photovoltaics (PV) don’t directly count
towards RPS 8
33% RPS 40% RPS 50% RPS0
20000
40000
60000
80000
100000
120000PV Behind-the-MeterPV Large Out-of-StatePV Large In-StateSolar ThermalWind Out-of-StateWind In-StateSmall HydroelectricBiogasBiomassGeothermalEl
ectr
icity
Pro
ducti
on (T
Wh/
Yr)
As the RPS is increased…[without additional operational flexibility]
GHG Emissions
9
33 40 500
10
20
30
40
50
60
RPS Target (%)
CO2 E
mis
sion
s (M
MTC
O2/
Yr)
Note: production costs do not include capital and maintenance costs,and are therefore only one important part of the total electricity cost
Production Costs
33 40 5001234567
RPS Target (%)
Prod
uctio
n Co
sts
($Bn
/Yr)
Renewable Curtailment
33 40 500
1
2
3
4
5
64.8
RPS Target (%)
% C
urta
ilmen
t
Reliability requirements cause renewable curtailment
10
0
1
2
3
4
5
64.8
1.51.0C
urt
ailm
en
t (%
)
50% RPS Base
Essential reliability services needed in grid operations[But some reliability requirements cause curtailment at a 50% RPS]
Load Followingand Regulation
DOWN
Increasing operational flexibilityat a 50% RPS:
What works and what doesn’t
12
13
Add non-generation flexibility:
StorageAdvanced Demand Response
Exports
Increase natural gas power plant fleet flexibility
Operate renewables more flexibly
14
Operating renewables flexibly is particularly effective
0123456
Hourly Curtailment
Sub-Hourly Curtailment
Curt
ailm
ent
(%)
Curtailment: nimble is much better than blocky
4.8
2.7
50% RPS Base
• More analysis needed on cost tradeoffs• Downward reserves from non-generation flexibility are valuable
Non-generation flexibility reducescurtailment and GHG emissions
Additional Non-Generation Flexibility (GW)= storage + advanced demand response + exports
15
0 3 6 90
1
2
3
4
5
6
0
10
20
30
40
5041.1 38.8 37.6 37.0
% C
urta
ilmen
t
CO2 E
mis
sion
s (M
MTC
O2/
Yr)
Gas power plant flexibility has important limits
16
Gas fleet changes in the Flexible Gas run:• Double ramp rate• Half minimum
power level• 1 hour start and
stop times• 2 hour minimum
uptime and downtime
• Providing some reliability services with gas requires electricity production, which “crowds out” renewables
Default Gas Flex-
ibility
Double Ramp Rate
Combined Cycle Half Minimum
Power Level
Flexible Gas
0
1
2
3
4
5
64.8 4.7
3.2 3.0
% C
urta
ilmen
t
• Duck Curve: “belly” is much more important than the “neck”
Non-Fossil Solutions:• Renewables can provide
reserves• 1 GW additional electricity
storage• 1 GW advanced demand
response• 1 GW net exports allowed
Operational flexibility:Non-fossil can go further than gas
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Flexible Gas
50% RPS Non-Fossil Solutions
01020304050
39.0 41.1 37.4
CO2
Emis
sion
s (M
MTC
O2
/Yr)
Flexible Gas
50% RPS Non-Fossil Solutions
0123456
3.0
4.8
1.1
% C
urta
ilmen
t
50% RPS Base
50% RPS Base
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33% RPS 50% RPS
Renewablecurtailment
Renewabledispatchability
• Increasing 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