Blackouts in California will be more prolonged and more severe than previously anticipated by the California Independent System Operator, according to a report released Tuesday by the North American Electric Reliability Council.
NERC anticipated firm demand may be curtailed for 260 hr over the summer with the average curtailment being 2,150 Mw, affecting nearly 2 million households. Blackouts will occur during peak and even during off peak hours because of California’s dependence on limited hydroelectric resources, NERC said.
The council forecast supply deficiencies in the range of about 4,500à¯¿½5,500 Mw at peak for each summer month. The ISO summer assessment reflected resource deficiencies of 3,347 Mw in June, falling to 1,444 Mw in July, and down to 686 Mw by September.
NERC called the ISO assessment “overly optimistic.”
NERC conducted its own analysis using its estimates of available resources, historical demand data, and data from each generating unit with assigned forced outage rate. This determined the number of hours during the summer that capacity shortages may occur.
“We’re still assessing the NERC report,” said Stephanie McCorkle, spokeswoman for ISO. “We are redoing our summer assessment and it should be available Monday.”
Without any interruptible demand, emergency conservation, or other demand reductions, NERC’s model estimated 700 hr of blackouts of 3,150 Mw. Response to the proposed retail rate increase could cut demand reducing the number of outages to 480 hr or 2,575 Mw, NERC said. If all measures to reduce demand are effective, NERC estimated outages would be 260 hr with 2,160 Mw out on average.
NERC forecast peak demand to be less than the ISO estimate because of recent rate increases and new conservation programs that were not included in ISO’s assessment. But the decreased demand is more than offset by fewer available resources.
The actual magnitude and duration of the blackouts will vary and be determined by further conservation and the ability of ISO operators to take appropriate action during emergencies, NERC said. Indeed, the ISO has already developed plans to cut off 6,000 Mw of firm demand in rotating outages, if necessary.
The resource deficiencies in NERC’s report compared to the ISO’s March 26 assessment can be accounted for by deratings from qualifying facilities, reduced output expected from internal hydroelectric facilities, increased exports, decreased imports, and more outages.
California can only count on about 5,800 Mw out of 10,300 Mw of capacity from the qualifying facilities or QFs. NERC reduced the output expected from wind units and also some output because of lingering credit concerns.
Imports from surrounding regions have fallen below the 8,000 Mw anticipated earlier that is generally needed to get through peak summer demand. Imports this summer are estimated by NERC to be about 2,500 Mw–1,000 Mw less than previously estimated by ISO. The main reason for this decrease is the drought in the Pacific Northwest has severely limited that region’s customary exports to California. Complicating the decrease in imports is an increase in exports of power. Some generators inside the ISO control area don’t have to sell to the ISO and can export power.
“Exports have nearly tripled from the summer of 1999 to the summer 2000 and the potential exists for a further increase,” NERC said.
Forced outages also will be greater than the 2,500 Mw estimated by the ISO, NERC said. Some maintenance planned for the winter had to be delayed or prematurely ended because of system emergencies.
This means unplanned outages could be much higher this summer. NERC said a more appropriate average level of forced outages would be 4,525 Mw, twice what is expected by ISO.
The ISO estimated deficiencies in California hydroelectric power would total just 1,000 Mw. NERC said the number will probably be closer to 2,800 Mw because of the drier conditions in California.
With respect to the prospect of new generation being available for summer, NERC identified 1,500 Mw of new capacity that could be expected to be operational by the end of the summer. But most of that won’t be available to serve high demand during June and July. ISO had estimated up to 3,371 Mw for August. NERC said it could not “find” data to support those estimates.