appendix a: probabilistic load resource balance …portfolio deficits. the data outputs of the...
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Snohomish County PUD – 2017 Integrated Resource Plan Appendix A| A-1
APPENDIX A: PROBABILISTIC LOAD
RESOURCE BALANCE MODEL
PUBLIC UTILITY DISTRICT #1 OF SNOHOMISH COUNTY
Prepared by
Generation, Power, Rates, and Transmission Management Division
Snohomish County PUD – 2017 Integrated Resource Plan Appendix A| A-2
PROBABILISTIC LOAD RESOURCE BALANCE
MODEL
Appendix A provides additional detail on the modeling assumptions PUD Staff used to measure
and evaluate future portfolio needs in the 2017 IRP analysis. The Appendix is organized into
three sections as follows:
1. Load Resource Balance (LRB) Model Methodology
2. Planning Standards
3. Resource Need by Scenario
1. LRB Methodology
The 2017 IRP used a probabilistic portfolio modeling approach to analyze the range of load
forecasts and the PUD’s existing and committed resources for five different scenarios, across the
20 year study period (2018-2037). This probabilistic approach considered the entire range of
possible combinations of load and output from the PUD’s existing and committed resources, and
simulated them together in a model that identified the scale, timing, and likelihood of potential
portfolio deficits. The data outputs of the Probabilistic Load Resource Balance model were then
used as inputs to the Portfolio Optimizer Model (described in Appendix B). The Portfolio
Optimizer Model identified the lowest reasonable cost portfolio additions that could address
portfolio needs. A flow diagram representative of the 2017 IRP modeling is shown in Figure A1.
Figure A1
Snohomish County PUD – 2017 Integrated Resource Plan Appendix A| A-3
How the Probabilistic LRB Model Works
The PUD’s Probabilistic LRB model created
simulations using a Monte Carlo framework, where
random draws of possible loads and resource output
combinations produced a potential load-resource
balance. In this way staff could identify the amount
of PUD surplus or deficit in meeting its customers’ needs over the study period. The simulation
in the 2017 IRP was repeated 5,000 times with different random draws that produced different
potential outcomes. This became the sample set from which statistical inferences were made
about the range and likelihood of particular occurrences.
For a simplified example of this process, imagine rolling two dice, one die represents customer
demand (load), and one die represents total available resource (supply). Each dice has six sides
with an equal chance of occurring, and a simulation of each individual dice rolled 5,000 times
would yield a chart as in Figure A2 below. The chart in Figure A2 shows that each value on the
“Supply-Side Dice” has an equal ~17% chance of occurring.
Figure A2
To build upon this simplified example, suppose each iteration of the Monte Carlo simulation
now includes the random roll of the Supply Dice and the Demand Dice, and records the Load
0%2%4%6%8%
10%12%14%16%18%
0 1 2 3 4 5 6 7
Freq
uen
cy o
f O
ccu
ren
ce
Dice Values
Supply-Side Dice: 5,000 Iterations
What is a Probabilistic Model?
A probabilistic model is a statistical
model that simulates the possible
outcomes based on historical data for the
purpose of forecasting the probability of
an event occurring in the future.
Snohomish County PUD – 2017 Integrated Resource Plan Appendix A| A-4
Resource Balance outcome (Supply minus Demand) of that iteration. In this case, there are
eleven possible Load Resource Balance outcomes, ranging from -5 (the result of a “1” Supply
Dice roll and a “6” Demand Dice Roll) to 5 (the result of a “6” Supply Dice Roll and a “1”
Demand Dice roll). All possible outcomes are shown in Table 1. The outcomes of the simulation
no longer have an equal chance of occurring as shown by the graph of their frequency of
occurrence (on y-axis) in Figure A3. Instead, the outcomes follow a triangle-shaped distribution
with a peak at zero, the most likely individual Load Resource Balance outcome in the 5,000
iteration simulation.
Table 1
Possible LRB Outcomes from Supply Roll – Demand Roll
Supply 1 Supply 2 Supply 3 Supply 4 Supply 5 Supply 6
Demand 1 0 1 2 3 4 5
Demand 2 -1 0 1 2 3 4
Demand 3 -2 -1 0 1 2 3
Demand 4 -3 -2 -1 0 1 2
Demand 5 -4 -3 -2 -1 0 3
Demand 6 -5 -4 -3 -2 -1 0
Figure A3
-2.00 5.0020.0% 0.0%80.0%
0%
2%
4%
6%
8%
10%
12%
14%
16%
18%
-6 -4 -2 0 2 4 6
Freq
uen
cy
Value of Supply Dice minus Resource Dice
"Dice Roll" Load Resource Balance: 5,000 Iterations
Snohomish County PUD – 2017 Integrated Resource Plan Appendix A| A-5
The data in this Figure A3 also allows for an estimation of a range of occurrences using the
statistical sample. For example, there is a roughly 20% chance that the Load Resource Balance
has a less than -2 balance, and no chance the balance will be greater than 5. This type of
information is helpful for planners who seek an estimate of the likelihood of potential deficits of
different magnitudes, and is one of the reasons this methodology is used in this IRP.
The 2017 IRP measures the entire range of possible load-resource balance outcomes for various
time horizons, such as Annual Average Energy for each year 2018-2037, and December Heavy-
Load Hours (HLH) from 2018-2037. The Planning Standards used by the IRP require the PUD to
meet its Load Resource Balance in 95% of Monthly HLH and Peak Week periods, so the Load
Resource Balance value at P5, or the lowest 5% of occurrences, provides the information needed
for subsequent portfolio optimization tests1. These values determine the scale of portfolio needs
in different time periods, by measuring the need at specific likelihoods that the Probabilistic
Load Resource Balance provides information on.
Time Horizons.
In the probabilistic model used in this IRP, the modelling for supply and demand is more
complex than the dice example. One of the sources of complexity is the need to model multiple
time periods within and across the 20-year planning period simultaneously as part of each Monte
Carlo iteration. In the dice example, there was only one time horizon, and the data presented only
the likelihood of different occurrences on the next set of dice rolls. In the IRP model, estimates
of the range of potential supply and demand side values are made in overlapping time periods,
with a structure that makes the values consistent across the time periods. The time horizons
measured in the IRP model are shown in Figure A4.
1 Planning Standards are discussed in detail in Section 5-8: Planning Standards in the 2017 IRP document
Snohomish County PUD – 2017 Integrated Resource Plan Appendix A| A-6
Figure A4
The time periods were simulated simultaneously, and the model for each time period corresponds
with the others, such that the model produces a detailed look at the potential range of resource
output (generation) across all time periods, bound by the relationships between the time periods.
In addition, because the time periods are simultaneously simulated in the same Monte Carlo
iteration, the results are part of the same sample set, and the statistics that describe portfolio
attributes across different time periods avoid a sample bias relative to each other.
Model Inputs.
The probability distribution for load and each resource asset was derived from actual historical
data, simulated production, and forecast models, based upon the best information available.
Figures A5 & A6 describe the components that produced the probabilistic estimates of load and
resources for each time horizon.
Snohomish County PUD – 2017 Integrated Resource Plan Appendix A| A-7
Figure A5
Snohomish County PUD – 2017 Integrated Resource Plan Appendix A| A-8
Figure A6
Model Outputs.
The effect of the model’s structure can be seen most clearly in the outputs of the Monte Carlo
simulation. Figure A7 illustrates the results from a 2,500 iteration Monte Carlo Simulation of the
2018 load on an annual average basis under Business-As-Usual Case Load Conditions. The P50
Snohomish County PUD – 2017 Integrated Resource Plan Appendix A| A-9
value in the graph is 779aMW, and represents the value where 50% of occurrences are below the
value, and 50% are above. This is the load value that would be expected, and, if the load forecast
was a point estimate, would be the value that would represent 2018 load. The range of possible
2018 load values is driven by the probabilistic variables that effect annual load as described in
Figure A5. In this case, the range and likelihood of annual load is principally driven by the range
and likelihood of weather volatility relative to historical average weather and industrial loads.
Warmer weather reduces load, while cooler weather increases load on an annual average basis
for the PUD. Industrial loads are variable over time but the variability is not significantly caused
by weather. The bell graph of likely loads does not look like the dice roll graph from Figure A2,
rather, the specific drivers of the PUD load create a complex probability distribution shape over
the 2,500 iterations of the simulation, and provides rich information on the range and likelihood
of potential loads.
Figure A7
While Figure A7 is specific to annual aMW in 2018, all time periods within the 20 year plan are
simultaneously simulated. As a result, it is possible to see the potential range of annual loads by
year for each year of the planning period. Figure A8 provides a summary of the range of possible
749.0 779.35.0% 50.0%45.0%
0.0%
0.5%
1.0%
1.5%
2.0%
2.5%
700
720
740
760
780
800
820
840
860
Freq
uen
cy in
2,5
00
iter
atio
ns
aMW
2018 Load Distribution (aMW)
Snohomish County PUD – 2017 Integrated Resource Plan Appendix A| A-10
annual average loads under the Business As Usual load conditions from 2018 to 2038. The very
top of the range of the green band represents the 95th percentile of the load occurrences, or, the
point at which 95% of annual load estimates in a 2,500 iteration simulation are below. In the case
of 2021, for example, that point is roughly 850 aMW. The very bottom of the range of the green
band represents the 5th percentile, or the point at which only 5% of occurrences in the 2,500
iteration simulation are below. In the year 2029 for example, there is only a 5% chance that load
would be below 850aMW, based on the 2,500 iteration simulation.
Figure A8
Similar to the Monte Carlo simulation of loads, the probability distribution of generating
resources is a complex shape driven by the variability of its component parts, described in Figure
A6. Contrary to the load model where the input variables produce an estimate for a single load
per time period, per iteration, the resource model estimates multiple resources (wind and hydro
for example) in each time period and adds them together to provide an estimate of portfolio
resource production for each iteration. It is possible in this model, as it is in reality, to have
strong hydro production, but weak wind production in a given time period, and vice versa. There
are also correlations between generating resources that inform how generation is likely to occur
for projects with similar characteristics, for example Washington State gorge-area wind projects,
700
750
800
850
900
950
1000
1050
2018 2020 2022 2024 2026 2028 2030 2032 2034 2036 2038
aMW
Load Distribution: 2018 to 2038 (aMW)
5% - 95%
+/- 1 Std. Dev.
Mean
Snohomish County PUD – 2017 Integrated Resource Plan Appendix A| A-11
which are likely to experience periods of high or low production together in a given time period.
The cumulative dynamics of each of the resources independently and interdependently create the
complex probability distribution shown in Figure A9, which represents the range and likelihood
of PUD existing resource production in 2018 on an annual average basis in a 2,500 iteration
Monte Carlo simulation.
Figure A9
Just as it was possible to display the range and variability of potential loads on an annual basis
across the 20-year planning period, it is also possible to chart the expected range of resource
production. The resulting chart in Figure A10 shows the volatility in resource production on an
annual basis as well as shifts in expected portfolio production as a result of expiring power
contracts, like the four wind project expiries depicted by dotted black lines on the chart.
Comparing the resource graph in Figure A10 to the load graph Figure A8 it is clear that the range
of potential resource production outcomes is much wider than the range of potential load
outcomes on an annual basis, under Base Case conditions.
892.6 1,000.95.0% 50.0%45.0%
0.000
0.001
0.002
0.003
0.004
0.005
0.006
0.007
0.008
0.009
0.010
850
900
950
1000
1050
1100
1150
Fre
qu
en
cy in
2,5
00
ite
rati
on
s
aMW
2018 Total Resource Distribution (aMW)
Snohomish County PUD – 2017 Integrated Resource Plan Appendix A| A-12
Figure A10
Along with the estimates for the range of loads and resources, the load resource balance of the
energy portfolio is also calculated, providing the range and likelihood of potential resource
adequacy across the planning period. Figure A11 displays the Load Resource Balance on an
annual basis from a Monte Carlo simulation run 2,500 times under Business As Usual Case
conditions. Any values below zero on the chart represent outcomes where the PUD’s existing
resources were not adequate to meet customer needs on an annual basis before new conservation
or additional resources. In the chart, the first such occurrence takes place in 2027, but the
likelihood and magnitude of the potential occurrence is low, with a 5% chance of a deficit at a
~25aMW magnitude or greater. As time progresses on the chart however, the magnitude and
likelihood of a deficit increases, such that by the year 2036, there is an expected deficit (the
Mean) of about 5aMW, and there is a 5% chance the deficit could be greater than 100aMW.
800
850
900
950
1000
1050
1100
11502018
2019
2020
2021
2022
2023
2024
2025
2026
2027
2028
2029
2030
2031
2032
2033
2034
2035
2036
2037
aMW
Total Resources 2018 to 2037
5% - 95%
+/- 1 Std. Dev.
Mean
Snohomish County PUD – 2017 Integrated Resource Plan Appendix A| A-13
Figure A11
The probabilistic model provides detailed information on the magnitude and likelihood of load
resource balance events across all of the time periods studied within the 20 year planning period
(listed in Table 1). The resulting information provides a rich data environment to help inform the
PUD about the size, timing, and likelihood of portfolio needs. For example, Figure A12 presents
the range and likelihood of all Load Resource Balance outcomes by 10% increment of likely
occurrence for each month in the year 2027. The shape of the potential deficits provide
information on when in the year the PUD is likely to be most deficit, by how much, and with
what certainty. The information is useful in considering what resources or programs could be
most beneficial to help the PUD ensure adequate resources. For example, the graph shows a near
certainty additional resources are needed in December, and a near certainty that resources are not
needed in May and June.
-150
-100
-50
0
50
100
150
200
250
300
350
aMW
Annual Avg LRB with no New Conservation (in aMW)
5% - 95%
+/- 1 Std. Dev.
Mean
Snohomish County PUD – 2017 Integrated Resource Plan Appendix A| A-14
Figure A12
2. Planning Standards
The probabilistic modeling approach of the PUD’s range of future load growth and output of
existing and committed resources provided the platform upon which to establish new planning
standards for the 2017 IRP analysis. These planning standards were established to ensure
adequate resources would be available on an annual, monthly and weekly basis to meet customer
demand across the IRP study period. An additional planning standard to test compliance with the
annual renewables compliance targets prescribed under the EIA (I-937) was also included in this
framework.
The Planning Standards used the outputs of the Probabilistic Load Resource Balance Model at
specific likelihoods to measure the risk of being inadequate in different time horizons, and the
amount of new resources that would be required to address the risk. The four planning standards
established in the 2017 IRP analysis to provide for an objective comparison of the impacts of
various scenario assumptions on future resource need are:
-300
-200
-100
0
100
200
300
400
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
2027 HLH Load Resource Balance by Monthly and Likelihood
P10 P20 P30 P40 P50 P60 P70 P80 P90
Snohomish County PUD – 2017 Integrated Resource Plan Appendix A| A-15
1. The Annual Energy Planning Standard measures the ability of the PUD to meet average
annual energy demand across the entire year. The PUD is deemed to have an energy need if
expected average annual load exceeds expected average annual resource production.
2. The Monthly On Peak Planning Standard measures the ability of the PUD to meet
monthly on peak demand, 19 out of 20 times, with its existing and committed resources. The
Monthly On Peak standard limits the quantity of on peak energy or capacity purchased from
the short-term wholesale market to satisfy any portfolio deficits, to no more than 100 aMW
in a given month.
3. The Peak Week Planning Standard measures the ability of the PUD to meet reliably meet
its highest on-peak demand during the most deficit week of the month, 19 out of 20 times,
with its existing and committed resources. The highest on peak demand has historically
occurred most often during December. The Peak Week standard limits the quantity of on
peak energy or capacity purchased from the short-term wholesale market to satisfy any
portfolio deficits to no more than 200 aMW.
4. The Regulatory Compliance Standard measures the portfolio’s compliance with the
provisions for determining cost effective conservation and annual renewables target set forth
under the Washington state Energy Independence Act (I-937). Several other regulatory
requirements including overgeneration events and consideration of renewable and
nonrenewable resources are addressed through this standard:2
Table 2 below shows how each Planning Standard was incorporated into the Portfolio Optimizer
as a parameter or constraint:
2 RCW 19.285 details conservation and renewables’ compliance requirements and RCW 19.280.030 addresses
developing a resource plan and considering overgeneration events.
Snohomish County PUD – 2017 Integrated Resource Plan Appendix A| A-16
Table 2
Planning Standard Probabilistic Model Data
Inputs
How the Planning Standard is
Used
Annual Energy Annual LRB
@P50 ≥ 0aMW after any needed
portfolio additions. No forecast
market purchases allowed to
meet standard
Annual LRB@P50 of the
existing portfolio before new
additions for all years 2018-
2037
Rule will mark as “invalid” any
portfolios with Annual LRB’s
less than 0 aMW in any year,
after portfolio additions.
Monthly On-Peak Monthly HLH LRB@P5 ≥
0aMW after any needed
portfolio additions,
Forecast Market Purchases to
Address Monthly HLH LRB
Deficit ≤100aMW
Monthly HLH LRB@P5 of the
existing portfolio before new
additions for 4 indicator months
per year (Dec, March, April,
August) for all years (2018-
2037)
Rule will mark as “invalid” any
portfolios with Monthly HLH
LRB’s less than -100 aMW in
any month and any year, after
portfolio additions (forecast
market purchases allowed to
cover LRB deficits between
0aMW to -100aMW).
Monthly Peak Week HLH
Monthly Peak Week LRB@P5≥
0aMW after any needed
portfolio additions,
Forecast Market Purchases to
Address Monthly Peak Week
HLH LRB Deficit ≤200aMW
Monthly Peak Week LRB@P5
of the existing portfolio before
new additions for the peak week
period of 4 indicator months per
year (Dec, March, April,
August) for all years (2018-
2037)
Rule will mark as “invalid” any
portfolios with Monthly Peak
Week HLH LRB’s less than -200
aMW in any month and any year,
after portfolio additions, (forecast
market purchases allowed to
cover LRB deficits between
0aMW to -200aMW).
Regulatory Compliance
“Valid” portfolio’s will meet
RPS compliance obligations
under the Target methodology
by some combination of
procuring renewable resources
with REC generating attributes
or purchasing unbundled RECs,
to augment RECs produced by
the existing portfolio.
Existing annual portfolio
production @P50 is imported
from the Probabilistic LRB
model for eligible resources.
Annual Load @P50 is also
imported from the LRB model
to set the annual RPS target in
MWh for each year 2018-2037.
Rule will not mark as “invalid”
any portfolios with insufficient
RECs (either through portfolio
resources or unbundled REC
purchases) to meet the RPS target
in any given year 2018-2037.
Table 3 shows the Load Resource Balance Positions at P5 for each of the four major Load
Growth Trajectories in the 2017 IRP for December On-Peak Hours (HLH) as an example of the
outputs of the Probabilistic Load Resource Balance Model used in further analysis. Because the
Monthly HLH Planning Standard requires that the Portfolio be in balance with no more than 100
aMW of forecast short-term market purchases, any values in the table below -100 aMW
represent time periods and magnitudes (below -100 aMW) that the Portfolio Optimizer
(described in Appendix B) must address with demand-side or supply-side resources to build a
portfolio that meets PUD planning standards. For example, in Table 3, the 2018 Load Resource
Snohomish County PUD – 2017 Integrated Resource Plan Appendix A| A-17
Balance has a deficit of 158aMW in the December On-Peak period at P5. This means to comply
with the PUD’s planning standards, at least 58aMW of resources that would be available during
the December on-peak period in 2018 must be added in order to make the portfolio comply with
the planning standards.
Table 3
December On-Peak Load Resource Balance with Existing/Committed Resources at P5
before New Resource/Conservation Additions (in On Peak aMW)
2018 2020 2022 2024 2026 2028 2030 2032 2034 2036
Climate Change -158 -166 -168 -183 -200 -222 -245 -272 -286 -303
Low Growth -118 -135 -132 -154 -174 -188 -220 -223 -225 -226
Business-As-Usual -111 -131 -153 -196 -228 -259 -300 -328 -355 -384
High Growth -111 -160 -192 -257 -298 -362 -426 -511 -588 -706
In prior IRP documents, the PUD used Planning Standards for two time horizons (Annual and
Winter) using two metrics (Critical and Blend). The resulting information gave the PUD an
indication of the scale of a potential load resource balance deficit in two circumstances (Critical
and Blend) and two time horizons (Annual and Winter), but did not provide any information on
the likelihood of occurrence or the appropriateness of the assumed load resource balance
conditions.
The previous annual portfolio metric, assumed hydro resource production at critical water
conditions, non-hydro resources at normal production, and load at normal weather, on an annual
basis. A sample depiction of this metric is presented in Figure A13. In the chart shown, the area
between the one load outcome (black dotted line) and the one resource outcome (blue bars)
represents the potential need of the PUD. What is not known is whether this combination of load
and resources is likely to occur, and whether the resulting proposed portfolio additions increase
or decrease risk.
Snohomish County PUD – 2017 Integrated Resource Plan Appendix A| A-18
Figure A13
Under the new methodology the PUD has access to information on thousands of possible load
resource balance outcomes across many more time horizons (Annual, Monthly aMW, Monthly
HLH, Monthly LLH, Monthly HLH Peak Week) allowing the PUD to develop a better
understanding of potential portfolio needs and the most beneficial shapes and deliveries of
resources to meet those needs. For example, Figure A14 shows the Load Resource Balance
under the Climate Change Load and Resource trajectory before New Conservation at P5 during
the December HLH period, the August HLH period– both drawn from the same 2,500 iteration
simulation. From the chart, it is clear that while the December HLH period is the larger portfolio
deficit in the short term at below -150aMW in 2018, at the end of the study period the August
HLH period is the more deficit period, with a portfolio deficit of less than -300 aMW in 2037.
The Monthly HLH Planning Standard and the Probabilistic Load Resource Balance model allows
the PUD to measure and address both of these needs and compare them against each other,
whereas the previous metric only measured one specific outcome across two possible time
horizons (Annual and Winter periods).
-
200
400
600
800
1,000
aMW
Previous Annual Load Resource Balance Metric
New Cumulative Conservation Winter Capacity ProductLandfill Gas WindGeothermal Loads-No New Conservation
Snohomish County PUD – 2017 Integrated Resource Plan Appendix A| A-19
Figure A14
3. Resource Need by Scenario
The PUD measured its potential resource need during the study period using the Probabilistic
Load Resource Balance Model at 760 different points in time. These 760 points in time include
monthly average, on-peak period, and peak week period estimates for every month and every
year from 2018-2037, and an annual average measurement for each year. The model produces
estimates of load, resource generation, and the load resource balance that different possible
combinations would produce at different likelihoods at each of those 760 points in time.
Figure A15 displays all of the point-in-time measurements for the Climate Change Scenario
Load Resource Balance at a P5 (the value likely to be exceeded 19 out of 20 times). The Annual
LRB which is shown at a P50. The data is shown in a heat map format, whereby the most
resource deficit periods are red, and most resource surplus periods are green. In general, more
(350)
(300)
(250)
(200)
(150)
(100)
(50)
0
50
100
aMW
Impact of Climate Change on Net Position PUD Load Resource Balance @P5 by Season
December HLH LRB August HLH LRB
Snohomish County PUD – 2017 Integrated Resource Plan Appendix A| A-20
deficit periods are found later in the time series, during Peak Week and HLH periods, and in the
summer and winter. In general, more surplus periods are found in the beginning of the time
series, during the spring, and during the annual average time period.
In analysis of the PUD’s Load Resource Balance deficits and the subsequent optimal portfolios
that resolved these deficits, it was found that a portfolio that adequately addressed all Load
Resource Balance deficits in the following time periods also resulted in the satisfactory
fulfillment of all 760 time periods: Annual Average LRB @P50, the December HLH and
December Peak LRB @ P5, and the August HLH LRB @ P5. For this reason, the Load Resource
Balance needs of different scenarios are shown in these time periods.
Snohomish County PUD – 2017 Integrated Resource Plan Appendix A| A-21
Figure A15: Load Resource Balances at P5 (and P50 for Annual Average) for all time periods in Climate Change Scenario
Snohomish County PUD – 2017 Integrated Resource Plan Appendix A| A-22
2018 2019 2020 2021 2022 2023 2024 2025 2026 2027 2028 2029 2030 2031 2032 2033 2034 2035 2036 2037
Annual Average @ P50 177 177 176 176 174 175 153 147 138 118 102 79 68 60 49 46 38 29 19 14
January (100) (101) (84) (80) (75) (73) (88) (88) (96) (91) (108) (120) (147) (147) (146) (145) (150) (158) (162) (169)
January HLH (163) (168) (151) (150) (147) (147) (155) (160) (165) (166) (185) (193) (222) (221) (223) (227) (231) (235) (241) (248)
January Peak Week (246) (248) (237) (234) (230) (227) (240) (246) (250) (253) (268) (274) (298) (300) (307) (306) (312) (311) (324) (328)
February (53) (56) (91) (44) (47) (43) (99) (58) (62) (71) (153) (98) (123) (130) (185) (137) (142) (145) (209) (158)
February HLH (103) (107) (145) (97) (100) (97) (157) (115) (118) (127) (215) (156) (185) (194) (257) (203) (207) (212) (280) (226)
February Peak Week (186) (188) (228) (179) (182) (178) (243) (197) (199) (215) (296) (229) (256) (261) (337) (272) (278) (284) (358) (297)
March (32) (28) (20) (32) (24) (26) (34) (39) (44) (78) (84) (88) (109) (117) (128) (129) (138) (139) (145) (140)
March HLH (79) (79) (76) (81) (75) (77) (89) (95) (102) (135) (140) (145) (172) (181) (189) (189) (201) (201) (212) (208)
March Peak Week (137) (144) (136) (144) (139) (140) (156) (165) (169) (188) (209) (206) (240) (251) (261) (258) (270) (272) (279) (287)
April 39 37 43 40 42 46 24 24 19 (25) (16) (53) (54) (66) (59) (71) (80) (78) (78) (89)
April HLH (6) (8) (1) (7) (6) (4) (23) (26) (31) (80) (74) (112) (111) (123) (118) (131) (142) (139) (136) (151)
April Peak Week (69) (70) (64) (74) (75) (72) (86) (90) (94) (121) (133) (160) (165) (175) (177) (183) (199) (194) (189) (204)
May 157 158 166 164 153 155 135 129 123 93 86 49 43 35 34 26 16 5 1 (2)
May HLH 139 90 144 92 129 86 114 58 97 14 61 (28) 18 (43) 3 (56) (13) (73) (29) (87)
May Peak Week 95 45 97 37 83 40 64 8 49 (21) 9 (71) (34) (88) (47) (105) (63) (121) (75) (135)
June 126 128 120 111 108 102 80 61 42 18 2 (41) (45) (60) (79) (85) (101) (111) (114) (137)
June HLH 136 70 123 55 113 45 79 (2) 43 (45) (1) (106) (54) (131) (89) (154) (111) (181) (132) (210)
June LLH 248 188 246 179 233 169 207 125 173 88 140 36 90 20 70 (2) 49 (23) 29 (45)
June Peak Week 70 16 60 1 49 (14) 26 (52) (14) (98) (63) (149) (121) (186) (155) (207) (172) (228) (188) (263)
July 61 49 47 39 36 31 (3) (17) (31) (59) (69) (116) (135) (148) (156) (165) (179) (193) (215) (228)
July HLH (10) (21) (23) (33) (39) (44) (80) (91) (110) (137) (151) (201) (216) (231) (239) (252) (268) (283) (302) (317)
July Peak Week (47) (58) (65) (73) (80) (82) (119) (133) (148) (173) (192) (235) (256) (270) (279) (291) (307) (321) (341) (359)
August 24 20 23 13 (2) (7) (30) (37) (51) (79) (103) (148) (157) (161) (177) (198) (210) (225) (226) (241)
August HLH (26) (31) (34) (46) (58) (65) (88) (100) (116) (146) (167) (213) (224) (233) (252) (269) (283) (299) (305) (322)
August Peak Week (81) (89) (91) (104) (114) (125) (142) (153) (169) (196) (218) (256) (269) (280) (296) (317) (328) (343) (350) (371)
September 46 38 30 22 16 17 (1) (21) (32) (42) (66) (90) (104) (124) (135) (148) (154) (158) (182) (194)
September HLH (14) (26) (30) (40) (46) (46) (69) (86) (99) (109) (133) (165) (179) (197) (209) (222) (229) (239) (259) (273)
September Peak Week (83) (91) (97) (109) (115) (117) (136) (153) (167) (189) (197) (224) (238) (258) (271) (286) (291) (300) (321) (339)
October 31 29 38 42 37 36 15 5 1 (15) (24) (57) (64) (71) (66) (75) (85) (100) (108) (114)
October HLH (9) (11) (3) (4) (8) (13) (31) (41) (45) (66) (76) (108) (115) (123) (123) (131) (144) (156) (163) (171)
October Peak Week (100) (101) (95) (98) (102) (106) (123) (135) (138) (160) (166) (198) (206) (214) (214) (226) (241) (250) (258) (266)
November (25) (17) (5) (20) (17) (15) (27) (28) (34) (67) (74) (95) (96) (97) (113) (122) (125) (133) (125) (139)
November HLH (94) (87) (79) (91) (91) (88) (102) (107) (115) (144) (153) (171) (175) (180) (192) (204) (205) (215) (213) (227)
November Peak Week (204) (199) (200) (204) (207) (210) (215) (227) (236) (267) (268) (296) (301) (301) (315) (328) (333) (341) (341) (357)
December (82) (89) (89) (90) (90) (75) (98) (111) (118) (143) (135) (159) (160) (183) (187) (192) (193) (196) (216) (220)
December HLH (158) (167) (166) (164) (168) (160) (183) (192) (200) (225) (222) (246) (245) (265) (272) (275) (286) (289) (303) (309)
December Peak Week (246) (250) (247) (253) (249) (257) (272) (278) (292) (317) (323) (348) (357) (373) (376) (388) (388) (399) (411) (422)
Snohomish County PUD – 2017 Integrated Resource Plan Appendix A| A-23
Resource Need - Climate Change Scenario
The Climate Change Scenario shows capacity resource needs before conservation on an Annual
Average basis, the December On-Peak period, the December Peak Week period, and the August
On-Peak period. There is no measured annual energy need in the Climate Change scenario.
Climate Change
- Annual
Average (P50)
2018 2020 2022 2024 2026 2028 2030 2032 2034 2036
Resources
940
968
977
976
974
954
930
931
932
933
Load (Adjusted)
763
792
802
823
836
852
863
882
894
914
Load Resource
Balance Deficit
Before New
Resources
177
176
174
153
138
102
68
49
38
19
0
200
400
600
800
1,000
1,200
aMW
Climate Change Load and Resources: Annual Energy before New Conservation
Existing Resources Load
Snohomish County PUD – 2017 Integrated Resource Plan Appendix A| A-24
Climate Change
- August HLH
@ P5
2018 2020 2022 2024 2026 2028 2030 2032 2034 2036
Resources
722
738
737
727
717
690
655
650
643
638
Load (Adjusted)
747
772
795
815
833
857
879
901
926
943
Load Resource
Balance Deficit
Before New
Resources
(26)
(34)
(58)
(88)
(116)
(167)
(224)
(252)
(283)
(305)
0
200
400
600
800
1000
1200
aMW
Climate Change Load and Resources in August HLH Before New Conservation
Existing resources Load
Snohomish County PUD – 2017 Integrated Resource Plan Appendix A| A-25
Climate
Change -
December
HLH @P5
2018 2020 2022 2024 2026 2028 2030 2032 2034 2036
Resources
1,107
1,157
1,174
1,199
1,219
1,232
1,246
1,280
1,298
1,322
Load
(Adjusted)
949
991
1,006
1,016
1,019
1,011
1,001
1,008
1,012
1,019
Load Resource
Balance Deficit
Before New
Resources
(158)
(166)
(168)
(183)
(200)
(222)
(245)
(272)
(286)
(303)
0
200
400
600
800
1,000
1,200
1,400
aMW
Climate Change Load and Resources: December HLH before New Conservation
Existing Resources Load
Snohomish County PUD – 2017 Integrated Resource Plan Appendix A| A-26
Climate
Change -
December
Peak Week @
P5
2018 2020 2022 2024 2026 2028 2030 2032 2034 2036
Resources
960
1,001
1,012
1,028
1,032
1,021
1,003
1,011
1,016
1,020
Load
(Adjusted)
1,206
1,248
1,261
1,299
1,324
1,344
1,360
1,386
1,403
1,431
Load Resource
Balance Deficit
Before New
Resources
(246)
(247)
(249)
(272)
(292)
(323)
(357)
(376)
(388)
(411)
Business As Usual w/No Carbon, w/California Carbon - Resource Need
The Business As Usual Scenario for both carbon policy levels (with No Carbon, with California
Carbon in 2022) shows capacity resource needs before conservation in the December and August
-
200
400
600
800
1,000
1,200
1,400
1,600
aMW
Climate Change Load and Resources December Peak Week before New Conservation
Existing Resources Load
Snohomish County PUD – 2017 Integrated Resource Plan Appendix A| A-27
On-Peak period, and the December Peak Week period. There is a limited annual energy need in
the Business as Usual scenario before conservation.
BAU - Annual
Average 2018 2020 2022 2024 2026 2028 2030 2032 2034 2036
Resources 972 991 989 974 971 950 926 926 926 926
Load (Adjusted) 778 806 821 841 857 874 890 908 925 944
Load Resource
Balance Deficit
Before New
Resources
194 185 168 133 114 76 36 18 1 -18
-
200
400
600
800
1,000
1,200
20
18
20
19
20
20
20
21
20
22
20
23
20
24
20
25
20
26
20
27
20
28
20
29
20
30
20
31
20
32
20
33
20
34
20
35
20
36
20
37
aMW
BAU Load and Resources: Annual Energy before New Conservation
Existing Resources Load
Snohomish County PUD – 2017 Integrated Resource Plan Appendix A| A-28
BAU - August
HLH @P5 2018 2020 2022 2024 2026 2028 2030 2032 2034 2036
Resources 749 765 760 746 743 721 691 692 691 692
Load (Adjusted) 741 762 780 797 811 832 845 862 881 892
Load Resource
Balance Deficit
Before New
Resources
8 3 -20 -51 -68 -111 -154 -170 -190 -200
-
200
400
600
800
1,000
20
18
20
19
20
20
20
21
20
22
20
23
20
24
20
25
20
26
20
27
20
28
20
29
20
30
20
31
20
32
20
33
20
34
20
35
20
36
20
37
aMW
BAU Load and Resources: August HLH before New Conservation
Existing Resources Load
Snohomish County PUD – 2017 Integrated Resource Plan Appendix A| A-29
BAU - December
HLH @P5 2018 2020 2022 2024 2026 2028 2030 2032 2034 2036
Resources 989 1016 1012 999 995 982 967 969 967 968
Load (Adjusted) 1101 1147 1164 1195 1223 1241 1267 1297 1322 1352
Load Resource
Balance Deficit
Before New
Resources
-111 -131 -153 -196 -228 -259 -300 -328 -355 -384
-
200
400
600
800
1,000
1,200
1,400
1,600
20
18
20
19
20
20
20
21
20
22
20
23
20
24
20
25
20
26
20
27
20
28
20
29
20
30
20
31
20
32
20
33
20
34
20
35
20
36
20
37
aMW
BAU Load and Resources: December HLH before New Conservation
Existing Resources Load
Snohomish County PUD – 2017 Integrated Resource Plan Appendix A| A-30
BAU - December
Peak Week @P5 2018 2020 2022 2024 2026 2028 2030 2032 2034 2036
Resources 995 1026 1023 1010 1010 988 972 969 972 970
Load (Adjusted) 1204 1258 1280 1308 1348 1359 1399 1422 1457 1491
Load Resource
Balance Deficit
Before New
Resources
-208 -232 -258 -298 -337 -370 -427 -453 -485 -520
Low Growth Scenario - Resource Need The Low Growth Scenario shows limited capacity resource needs before conservation in the
December and August On-Peak period, and the December Peak Week period. There is no energy
need in the Low Growth scenario before conservation.
-
200
400
600
800
1,000
1,200
1,400
1,600
20
18
20
19
20
20
20
21
20
22
20
23
20
24
20
25
20
26
20
27
20
28
20
29
20
30
20
31
20
32
20
33
20
34
20
35
20
36
20
37
aMW
BAU Load and Resources: December Peak Week before New Conservation
Existing Resources Load
Snohomish County PUD – 2017 Integrated Resource Plan Appendix A| A-31
Low - Annual
Average 2018 2020 2022 2024 2026 2028 2030 2032 2034 2036
Resources 957 971 981 974 971 951 926 926 926 926
Load (Adjusted) 768 788 798 813 821 828 833 837 836 838
Load Resource
Balance Deficit
Before New
Resources
190 183 183 161 150 122 93 88 90 88
-
200
400
600
800
1,000
1,200
20
18
20
19
20
20
20
21
20
22
20
23
20
24
20
25
20
26
20
27
20
28
20
29
20
30
20
31
20
32
20
33
20
34
20
35
20
36
20
37
aMW
Low Load and Resources: Annual Energy before New Conservation
Existing Resources Load
Snohomish County PUD – 2017 Integrated Resource Plan Appendix A| A-32
Low - August
HLH @P5 2018 2020 2022 2024 2026 2028 2030 2032 2034 2036
Resources 736 749 756 746 743 721 691 692 691 692
Load (Adjusted) 731 746 759 770 776 787 790 792 796 791
Load Resource
Balance Deficit
Before New
Resources
5 2 -3 -24 -33 -66 -99 -100 -105 -99
-
200
400
600
800
1,000
20
18
20
19
20
20
20
21
20
22
20
23
20
24
20
25
20
26
20
27
20
28
20
29
20
30
20
31
20
32
20
33
20
34
20
35
20
36
20
37
aMW
Low Load and Resources: August HLH before New Conservation
Existing Resources Load
Snohomish County PUD – 2017 Integrated Resource Plan Appendix A| A-33
Low - December
HLH @P5 2018 2020 2022 2024 2026 2028 2030 2032 2034 2036
Resources 971 991 1003 999 996 982 967 968 967 969
Load (Adjusted) 1089 1126 1134 1153 1170 1170 1187 1192 1191 1195
Load Resource
Balance Deficit
Before New
Resources
-118 -135 -132 -154 -174 -188 -220 -223 -225 -226
-
200
400
600
800
1,000
1,200
1,400
20
18
20
19
20
20
20
21
20
22
20
23
20
24
20
25
20
26
20
27
20
28
20
29
20
30
20
31
20
32
20
33
20
34
20
35
20
36
20
37
aMW
Low Load and Resources: December HLH before New Conservation
Existing Resources Load
Snohomish County PUD – 2017 Integrated Resource Plan Appendix A| A-34
Low - December
Peak Week @P5 2018 2020 2022 2024 2026 2028 2030 2032 2034 2036
Resources 982 1026 1023 1010 1010 988 972 969 972 970
Load (Adjusted) 1196 1229 1240 1262 1278 1287 1308 1307 1307 1313
Load Resource
Balance Deficit
Before New
Resources
-214 -230 -227 -253 -275 -296 -336 -336 -338 -342
High Growth Scenario - Resource Need The High Growth Scenario shows significant capacity resource needs before conservation in the
December and August On-Peak period, and the December Peak Week period. There is a
significant annual energy need in the High Growth scenario before conservation.
-
200
400
600
800
1,000
1,200
1,400
20
18
20
19
20
20
20
21
20
22
20
23
20
24
20
25
20
26
20
27
20
28
20
29
20
30
20
31
20
32
20
33
20
34
20
35
20
36
20
37
aMW
Low Load and Resources: December Peak Week before New Conservation
Existing Resources Load
Snohomish County PUD – 2017 Integrated Resource Plan Appendix A| A-35
High - Annual
Average 2018 2020 2022 2024 2026 2028 2030 2032 2034 2036
Resources 987 992 988 974 971 950 926 926 926 926
Load (Adjusted) 788 826 846 880 907 943 977 1031 1086 1165
Load Resource
Balance Deficit
Before New
Resources
199 165 142 94 64 7 -51 -105 -159 -240
-
200
400
600
800
1,000
1,200
1,400
20
18
20
19
20
20
20
21
20
22
20
23
20
24
20
25
20
26
20
27
20
28
20
29
20
30
20
31
20
32
20
33
20
34
20
35
20
36
20
37
aMW
High Load and Resources: Annual Energy before New Conservation
Existing Resources Load
Snohomish County PUD – 2017 Integrated Resource Plan Appendix A| A-36
High - August
HLH @P5 2018 2020 2022 2024 2026 2028 2030 2032 2034 2036
Resources 761 765 762 746 743 722 691 692 691 692
Load (Adjusted) 750 781 808 835 860 899 927 980 1035 1104
Load Resource
Balance Deficit
Before New
Resources
11 -15 -46 -88 -117 -177 -236 -288 -344 -412
-
200
400
600
800
1,000
1,200
1,400
20
18
20
19
20
20
20
21
20
22
20
23
20
24
20
25
20
26
20
27
20
28
20
29
20
30
20
31
20
32
20
33
20
34
20
35
20
36
20
37
aMW
High Load and Resources: August HLH before New Conservation
Existing Resources Load
Snohomish County PUD – 2017 Integrated Resource Plan Appendix A| A-37
High - December
HLH @P5 2018 2020 2022 2024 2026 2028 2030 2032 2034 2036
Resources 1009 1017 1011 1000 996 982 967 968 967 968
Load (Adjusted) 1121 1177 1203 1256 1293 1344 1393 1479 1555 1675
Load Resource
Balance Deficit
Before New
Resources
-111 -160 -192 -257 -298 -362 -426 -511 -588 -706
-
500
1,000
1,500
2,000
20
18
20
19
20
20
20
21
20
22
20
23
20
24
20
25
20
26
20
27
20
28
20
29
20
30
20
31
20
32
20
33
20
34
20
35
20
36
20
37
aMW
High Load and Resources: December HLH before New Conservation
Existing Resources Load
Snohomish County PUD – 2017 Integrated Resource Plan Appendix A| A-38
High - December
Peak Week @P5 2018 2020 2022 2024 2026 2028 2030 2032 2034 2036
Resources 1018 1029 1016 1011 1005 994 969 971 970 974
Load (Adjusted) 1225 1291 1313 1373 1419 1480 1542 1635 1716 1863
Load Resource
Balance Deficit
Before New
Resources
-207 -263 -296 -363 -414 -487 -574 -664 -746 -890
-
500
1,000
1,500
2,000
2,500
20
18
20
19
20
20
20
21
20
22
20
23
20
24
20
25
20
26
20
27
20
28
20
29
20
30
20
31
20
32
20
33
20
34
20
35
20
36
20
37
aMW
High Load and Resources: December Peak Week before New Conservation
Existing Resources Load
Snohomish County PUD – 2017 Integrated Resource Plan Appendix A| A-39