Council needs assessment reserve margins, 2031 (draft Ninth Power Plan)
The Northwest Power and Conservation Council's needs assessment for 2031, the region as a whole, read cell by cell from its needs assessment workbook: for each of five need studies, the planning reserve margin per season that its capital expansion model (OptGen) must build to, with the GENESYS and OptGen seasonal peak loads, the existing system's resource contributions, the need and the load-resource balance it is made from; and the annual firm-energy adequacy reserve margin with its monthly duration value-at-risk, threshold, firm-energy adjustment and average monthly load. Res & Tx is the one study every New Resource & Transmission Risk sensitivity shares (Appendix M, PDF page 25); the other four test hydro operations (Appendix M Table M-10: 2020 BiOp Flex Spill Operation, 2023 RCBA Operations, Recommended Spill and MOP Targets, Limited Flex Operation). The studies share the existing system and the High Growth pathway's load, and the existing system falls short of the Council's adequacy criteria in every one; the margins are the Council's signal to its model, not an observation, not a utility's requirement and not a forecast. Loads, resources and need are MW; the firm-energy adjustment is average megawatts (the Council writes aMW; the dictionary unit here is MWa), as is the average monthly load it is divided by; margins are fractions of the load each row names (0.286 is 28.6% above that load); duration value-at-risk is hours. They are never combined, studies are never averaged and seasons or months never summed. The Council's own totals (Total Resources, the load-resource balance, each study's seasonal need and annual margin) are reconciled against the figures they are made from. The study is final; the plan it supports is a draft open for public comment.
At a glance
Period
2031–2031
One row is
Need study x season (planning reserve margin) or month and year (energy adequacy reserve margin) x quantity, 2031, the region
Built from source rows of
need study x season (planning reserve margins) or month (energy adequacy reserve margin) x quantity, for 2031 and the region
Evidence and method
modeled · directThe Council's needs assessment for 2031, the region as a whole: the signals its adequacy model GENESYS hands its capital expansion model OptGen, as a planning reserve margin per season (a fraction above OptGen's seasonal peak load) and an annual firm-energy adequacy reserve margin (a fraction of load), per need study. The existing system without new resources falls short in every study (Reminder About Adequacy Metrics!J20); the margins are what OptGen must build to, not an observation, not a utility's requirement and not a forecast. Loads, resource contributions and the need are MW as the column headers print them; the firm-energy adjustment is aMW (the Council's unit, MWa here) and the average monthly load it is divided by is recorded in MWa; margins are fractions; the monthly duration VaR and its threshold are hours. The five studies share the existing system and load; the load is the High Growth pathway's (Appendix M, PDF page 21). Studies are never averaged, seasons and months never summed, and a fraction, MW and MWa are never combined. The study is final (the file name says so); the plan it supports is draft 2026-3, open for comment through October 16, 2026.
Seasonal peak loads (GENESYS's average and OptGen's), the existing system's contributions (two-hour sustained peaking hydro, thermal, battery, wind and solar, market), their total, the need net of balancing reserves and the load-resource balance, each in MW as its column header prints it. The load-resource balance is Total Resources less the GENESYS load and is negative where the season is short.
value
MWa
The monthly firm-energy adjustment the Council heads 'aMW Adjustment' (Appendix M Table M-9, 'Firm Energy Adjustment (aMW)') and the GENESYS average monthly load it is divided by. The load's header prints no unit; the Council divides the aMW adjustment by it to state a percent above load (Appendix M PDF pages 20-21), so it is an average load in MWa.
value
h
The monthly duration value-at-risk (97.5th percentile of the longest shortfall events) and the 8-hour threshold it is held to, in hours ('VaR Duration (hr)', Reminder About Adequacy Metrics!F21:F23; Appendix M Figure M-6).
value
fraction
Reserve margins as the workbook stores them, a fraction above the load named in the row's denominator: the adequacy margin above the GENESYS load, the seasonal peaking margin with a 6% contingency and the planning reserve margin above OptGen's load (Appendix M Eqs 1-3), the monthly energy margin above the average monthly load, and the annual energy margin, the largest monthly one.
Coverage 2031–2031
695 values · 5 council need studies
Rows per year as the source dates them; a row without a date is its own line. For each measure: rows with a value, rows listed without one, rows where it does not apply. Counts are values, not quantities.
Year
council need studies
values
capacityMW
firm energyMWa
durationh
marginfraction
2031
5
695
3000 without · 0 n/a
1200 without · 0 n/a
1200 without · 0 n/a
1550 without · 0 n/a
By unitper year
Year
MW
MWa
fraction
h
2031
300
120
155
120
By quantityper year
Year
adequacy margin
annual energy arm
battery
duration var threshold
firm energy adjustment
genesys average monthly load
genesys average seasonal peak load
hydro sustained peaking
load resource balance
market
monthly duration var
monthly energy arm
need net of balancing reserves
optgen seasonal peak load
planning reserve margin
seasonal peaking margin and contingency
thermal
total resources
wind and solar
2031
30
5
30
60
60
60
30
30
30
30
60
60
30
30
30
30
30
30
30
What is missing, and why
Listed without a reported value · capacityRows with no value for this measure; published as null, never zero
0 values
Listed without a reported value · firm energyRows with no value for this measure; published as null, never zero
0 values
Listed without a reported value · durationRows with no value for this measure; published as null, never zero
0 values
Listed without a reported value · marginRows with no value for this measure; published as null, never zero
0 values
In the source, not yet includedNot read: the adequacy metrics each study fails (Reminder About Adequacy Metrics: LOLEV events, duration, peak and energy value-at-risk against their thresholds); each study's hour-by-month need grids and the selection logic behind its monthly need; and the worked example beside the Res & Tx block. Each study's final seasonal need is read only to reconcile the need column.
Not computedonly the reserve margin sheets are adapted
The workbook is pinned by its SHA-256 in the source registry: a changed byte fails acquisition rather than becoming a new edition silently, so the table changes only when the pin is reviewed and moved. No timed refresh.www.nwcouncil.org/energy/ninthpowerplan/technical-elements/ ↗
council_needs_assessment.rows_valid{"negative_where_not_allowed":0,"rows":695,"unit_locators":{"MW":"PlanningReserveMargins row 3 of each study block, each header ending '(MW)'; <study> Need!R5 'MW'","MWa":"MonthlyEnergyARMs 'aMW Adjustment' (Appendix M Table M-9 'Firm Energy Adjustment (aMW)', PDF page 21). 'GENESYS Avg Monthly Load' prints no unit: the Council divides the aMW adjustment by it to state a percent above load (H15 =F15/G15; Appendix M PDF page 20, 'what percent above load does this aMW represent', and page 21, 'Annual Energy ARM = Max(FirmEnergy / AverageLoad)'), so it is an average load, recorded in MWa","fraction":"stored as decimals the workbook formats as percents; Appendix M prints them as percents (Tables M-14 and M-15, PDF pages 28-29): 'Both the PRM and ARM serve as a percentage above load' (PDF page 1)","h":"MonthlyEnergyARMs 'Monthly Duration VaR' and 'Threshold': Reminder About Adequacy Metrics!F21:F23 'VaR Duration' '(hr)' threshold 8; Appendix M Figure M-6 axis 'Hour' (PDF page 27) and the 8-hour threshold (PDF page 17)"},"unit_or_denominator_not_the_quantitys":0,"unknown_missing_reason":0,"unknown_study_period_or_year":0,"value_and_reason_inconsistent":0}
Passed
council_needs_assessment.totals_reconcile{"by_relation":{"annual_energy_arm = the largest monthly energy ARM":5,"load_resource_balance = total_resources - GENESYS load":30,"monthly_energy_arm = adjustment / average monthly load":60,"need_net_of_balancing_reserves = the study's final seasonal need":30,"total_resources = sum of the five resource columns":30},"compared":155,"disagreement_count":0,"disagreements":[],"tolerance":{"MW":0.001,"MWa":0.001,"fraction":1e-9,"h":1e-9}}
Passed
No corrections apply to this dataset in this release. Earlier editions: not available (earlier releases did not retain per-dataset edition comparisons).