1. Study Results February 10, 2015 W ESTERN E LECTRICITY C OORDINATING C OUNCIL

2. PC03 Decreased Load The purpose of the Decreased-Load sensitivity case is to continue to attempt to model and plan for a wide variety of futures. – 10% decrease in load WECC wide This case is intended to provide the other bookend on the 2024 Common Case. – What are the utilization/congestion impacts – What is the resulting planning reserve margins 2 W ESTERN E LECTRICITY C OORDINATING C OUNCIL

3. 10% Decrease in load 3 W ESTERN E LECTRICITY C OORDINATING C OUNCIL

4. 10% Decrease in load 4 W ESTERN E LECTRICITY C OORDINATING C OUNCIL

5. Generation Change 5 W ESTERN E LECTRICITY C OORDINATING C OUNCIL

6. Generation Change 6 W ESTERN E LECTRICITY C OORDINATING C OUNCIL

7. Production Cost and CO 2 7 Category2024 PC1 15-01-192024 PC3 Low LoadDifference Conventional Hydro238,660,400238,647,732(12,668) Energy Storage3,684,9293,486,388(198,541) Steam - Coal231,197,415212,328,340(18,869,075) Steam - Other3,014,0112,545,398(468,613) Nuclear56,167,02356,028,747(138,276) Combined Cycle274,985,932212,222,018(62,763,914) Combustion Turbine55,245,01136,909,352(18,335,659) IC803,017392,115(410,901) Other3,365,2803,365,100(180) DG/DR/EE - Incremental17,838,66117,835,507(3,154) Biomass RPS19,528,18718,626,124(902,063) Geothermal31,944,68031,902,272(42,408) Small Hydro RPS4,360,0254,358,486(1,539) Solar35,866,28335,863,813(2,470) Wind73,705,85273,639,029(66,823) == Total ==1,050,366,706948,150,421(102,216,285) (0.097315) Cost (M$)22,39918,148(4,251) CO2 Cost (M$)1,050855(195) CO2 Amount (MMetrTn)368315(53) Dump Energy (MWh)433,485506,11372,628 Pumping (PL+PS) (MWh)15,528,45715,277,586(250,871)

8. Planning Reserve Margins 8 W ESTERN E LECTRICITY C OORDINATING C OUNCIL Common Case AZ-NM-NVBasinAlberta British ColumbiaCA-NorthCA-SouthNWPPRMPA Planning Reserve %13.6%13.7%12.6% 15.0%15.2%17.5%14.5% Peak Load34,65215,55414,3409,03429,39743,06728,05313,465 Gen Requirement (Peak Load + Reserves)39,36517,68516,14710,17233,80749,61332,96215,417 Gen Capacity Available at time of Peak in Dataset44,04518,88915,71915,47933,66140,27835,87915,810 Initial Gap-4,681-1,204428-5,3071469,335-2,917-393 Gap Adjustment (Joint Ownership Plants)4,1891,194000-5,7770394 Gap Adjustment (Region-Region Transfers)49110-4284280-3,4172,917 Resulting PRM13.6%13.7%12.6%66.6%14.5%14.9%17.5%14.5% Unserved Load-None Decreased Load AZ-NM- NVBasinAlberta British ColumbiaCA-NorthCA-SouthNWPPRMPA Planning Reserve %13.6%13.7%12.6% 15.0%15.2%17.5%14.5% Peak Load31,18713,99912,9068,13126,45738,76025,24812,119 Gen Requirement (Peak Load + Reserves)35,42815,91614,5329,15530,42644,65229,66613,876 Gen Capacity Available at time of Peak in Dataset44,04518,88915,71915,47933,66140,27835,87915,810 Initial Gap-8,617-2,973-1,186-6,324-3,2354,374-6,213-1,934 Gap Adjustment (Joint Ownership Plants)4,1891,194000-5,7770394 Gap Adjustment (Region-Region Transfers)49110-4284280-3,4172,917 Resulting PRM26.2%26.3%25.1%85.1%27.2%27.6%30.6%27.2%

9. Congested Paths 9 W ESTERN E LECTRICITY C OORDINATING C OUNCIL Interface_Name Congestion Cost (K$) Congestion Hours (Hrs) P01 Alberta-British Columbia16048 P15 Midway-LosBanos49825 P18 Montana-Idaho1,027103 P32 Pavant-Gonder InterMtn- Gonder 230 kV14643 P36 TOT 317236 P45 SDG&E-CFE499188

10. Path Flows 10 W ESTERN E LECTRICITY C OORDINATING C OUNCIL

11. Path Flows 11 W ESTERN E LECTRICITY C OORDINATING C OUNCIL

12. Observations 12 W ESTERN E LECTRICITY C OORDINATING C OUNCIL Decreasing load by 10% across the Western Interconnection has the following effects: Gas- and coal-fired generation primarily are ramped back under decreased loads Roughly -19% in CO2 cost and production cost across the Western Interconnection Congestion is decreased from that of the Common Case

13. Questions 13 W ESTERN E LECTRICITY C OORDINATING C OUNCIL