PacifiCorp 2007 Integrated Resource Plan (May 30, 2007)

PacifiCorp – 2007 IRPChapter 4 – Resource Needs AssessmentEnergy Balance DeterminationMethodologyThe energy balance shows the average monthly on-peak and off-peak surplus (deficit) of energy.The on-peak hours are weekdays and Saturdays from hour-ending 7:00 am to 10:00 pm; off-peakhours are all other hours. The existing resource availability is computed for each month and dailytime block without regard to economic considerations. Peaking resources such as the Gadsbyunits are counted only for the on-peak hours. This is calculated using the formulas that follow.Please refer to the section on load and resource balance components for details on how energyfor each component is counted.Existing Resources = Thermal + Hydro + DSM + Renewable + Purchase + QF + InterruptibleThe average obligation is computed using the following formula:Obligation = Load + SalesThe energy position by month and daily time block is then computed as follows:Energy Position = Existing Resources – Obligation – Reserve Requirements (12% PRM)Energy Balance ResultsFigures 4.6 through 4.8 show the energy balances for the system, west control area, and east controlarea, respectively. They show the energy balance on a monthly average basis across allhours, and also indicate the average annual energy position. The cross-over point, where the systembecomes energy deficient on an average annual basis, is 2009, absent any economic considerations.85