The California Independent System Operator issued a Stage Two statewide electrical emergency alert today, ordering utilities Pacific Gas & Electric Co., Southern California Edison Co., and San Diego Gas & Electric Co. to activate voluntary load management programs in phases, requiring curtailment of enough megawatts to maintain a 5% operating reserve.
A pervasive heat wave covering much of the west is causing demand for power to chase the mercury today, the California ISO said. A Stage Two emergency is called when operating reserves dip below 5% or are expected to within the next 2 hours.
Operating reserves for much of the western US are slim due to the widespread heat, it said. Electricity imported by California from the Northwest is particularly scarce because power is needed within that region, which is also experiencing lingering hot weather.
Portland, Ore., is expected to break records with a high today that could top 100� F. Meanwhile, temperatures in Phoenix, Ariz., are also hot, so power imported from the Southwest is limited as well. The California ISO anticipates reaching a peak load of 44,205 Mw later today. The Stage Two alert is in effect until 7 p.m. Pacific Standard Time. An earlier Stage One alert is in effect until 8 p.m.
The ISO urged interruptible customers to wait to shed their electrical load until specified to do so by their local utility. Interruptible customers, mainly commercial users, receive a reduced rate in exchange for curtailing power when asked to do so for reliability purposes.
While not anticipated today, the ISO said that if an operating reserve shortfall of less than 1.5% is unavoidable, Stage Three is initiated. Involuntary curtailments of service to customers, including "rolling blackouts," are probable during this emergency declaration.
California ISO is chartered by the state to manage the flow of electricity along the long-distance, high-voltage power lines that make up the bulk of California's transmission system. It assumed responsibility for the transmission system in March1998, when California opened its energy markets to competition and the state's investor-owned utilities turned their private transmission power lines over to the California ISO to manage.
