PacifiCorp 2007 Integrated Resource Plan (May 30, 2007)

PacifiCorp – 2007 IRPChapter 4 – Resource Needs AssessmentTable 4.4 – Historical Coincidental Peak Load - SummerAverage AnnualGrowth Rate Total OR WA WY CA UT ID1995-2005 2.2% 0.8% 1.7% 0.0% 2.2% 5.2% 1.5%The system peak load is expected to grow at a slightly faster rate than the overall load due to thechanging mix of appliances over time. Table 4.5 below shows that for the same time period thetotal peak is expected to grow by 2.6 percent. Until recently, the system peak occurred in thewinter months. Due to a changing appliance mix from an increasing demand for summer spaceconditioning in the residential and commercial classes, and a reduction in electric related spaceconditioning in winter months, the system peak has started occurring in summer months. Pacifi-Corp expects this condition to continue. Therefore, the increasing summer load and decreasingwinter loads are expected to result in a faster growing system peak than total load until changesin space conditioning equipment mix ends.Table 4.5 – Forecasted Coincidental Peak Load in MegawattsYear Total OR WA WY CA UT ID SE-ID2006 9,577 2,684 816 1,094 156 4,011 561 2562007 9,243 2,076 699 1,044 147 4,298 632 3472008 9,440 2,075 702 1,145 147 4,409 631 3312009 9,752 2,235 702 1,282 159 4,420 678 2762010 10,261 2,254 729 1,416 141 4,720 696 3052011 10,488 2,314 757 1,473 128 4,932 573 3112012 10,836 2,320 766 1,569 155 4,973 686 3672013 10,989 2,328 767 1,613 156 5,061 693 3712014 11,157 2,331 773 1,648 158 5,184 708 3552015 11,296 2,326 774 1,669 171 5,337 719 3002016 11,619 2,314 775 1,733 163 5,547 745 342AAG2007-2016 2.6% 1.2% 1.2% 5.8% 1.2% 2.9% 1.8% -0.2%AAG2016-2026 2.2% 1.5% 1.6% 1.9% 0.4% 2.9% 1.4% 1.0%One noticeable aspect of the states contribution to the system coincidental peak forecast is thatthey do not continuously increase from year to year, even though the total system peak and eachstate’s individual peak loads generally increase from year to year. This behavior occurs becausestate level coincident peaks do not occur at the same time as the system level coincident peak,and because of differences among the states with regard to load growth and customer mix. Whileeach state’s peak load is forecast to grow each year when taken on its own, its contribution to thesystem coincident peak will vary since the hour of system peak does not coincide with the hourof peak load in each state. As the growth patterns of the class and states change over time, thepeak will move within the season, month or day, and each state’s contribution will move accordingly,sometimes resulting in a reduced contribution to the system coincident peak from year toyear in a particular state. This is seen in a few areas in the forecast as well as experienced in history.For example, the Idaho state load is driven in the summer months by the activity in the irrigationclass. The planting and irrigating practices usually cause this state to experience the65