2009 Pacific Northwest Resource Adequacy Assessment Resource Adequacy Technical Committee October 16, 2009

2 Current Assessment Method 1.Simulate futures using random variables Runoff volumes Temperatures (loads) Thermal outages Wind generation 2.Define “bad” events Energy: total winter curtailment > 1,200 MW-days Capacity: any hour curtailment > 3,000 MW

October 16, Current Method (cont’d) 3.LOLP = number of futures with bad events divided by the total number of futures Winter energy and capacity Summer capacity 4.5% LOLP = adequate supply 5.Translate 5% LOLP into deterministic metrics Annual load/resource balance (energy) Sustained-peak surplus capability (capacity)

October 16, Metrics Annual Needs – Annual average generating capability minus annual average load, referred to as the annual load/resource balance (in MWa) Hourly Needs – Surplus hourly generating capability over expected sustained peak hourly load, referred to as the reserve margin (in percent)

October 16, Thresholds Energy – Load/resource balance Physical = 0 MWa Economic = approx. 3,000 MWa Capacity – Reserve margin Physical Winter = 23% Physical Summer = 24% Economic = ?

October 16, Energy Load/Resource Balance Expected Build-Out Schedule

October 16, January Capacity Reserve Margin Expected Build-Out Schedule

October 16, July Capacity Reserve Margin Expected Build-Out Schedule

October 16, Adequacy Violation Dates (3 and 5 years out are 2012 and 2014) Energy 2025 January Peaking 2030 July Peaking 2013

October 16, Adequacy Status - Yellow Regional status = Yellow Light Warning July capacity inadequacy 4 years out

October 16, Implementation Actions Green Green Proceed with normal planning activities Compare results with other regional reports Yellow Yellow Regional report Forum review of data and assumptions Red Red Regional conference Regional review of data and assumptions Identify inadequate utilities

October 16, Current Activities RPS legislation is pushing wind development Utilities are actively pursuing new resource acquisition Power plan resources maintain July capacity adequacy through 2028 Forum will review data and methodology