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California scrambles for interruptible load to avoid blackouts


By ANN DE ROUFFIGNAC
OGJ Online

HOUSTON, Feb. 14, 2001—With areas of California on the verge of rolling blackouts Wednesday, the California Independent System Operator (ISO) asked Southern California Edison Co. to cut 1,100 MW in “interruptible” load.

Getting customers to curtail load or getting more generation scheduled is the only way to avoid blackouts, says Patrick Dorinson, ISO spokesman. He said 10,700 MW remains off line, up from 8,100 MW Monday. But the number of customers in the interruptible program with unfilled contractual obligations to curtail power is dwindling. This is the thirtieth straight day that a Stage 3 electricity emergency alert has been called and the ISO has frequently depended on 1,700 MW of interruptible load from SCE to keep the grid in balance.

The California Public Utilities Commission (PUC) suspended penalties for customers who don’t comply, pending the outcome of public hearings. The PUC is considering amendments to the program for summer. Meanwhile, load reduction is dependent on customers previously in the program volunteering to shut off electricity.

“It’s obvious that we need these customers for curtailment,” says Michael Dozier, manager of contracts at the ISO.

With a 3,000-6,000 MW shortfall of electricity forecast for the summer, interruptible customers will be essential to reduce the number of involuntary blackouts, he says.

On its own initiative, the ISO designed a separate demand response program and received responses to its request for bids last week.

“We were pleased with the responses that include several hundred megawatts of load,” Dozier says. “We will submit the selected bids to our board on Feb. 21 for approval.”

The program is directed at “load aggregators” such as utilities or entrepreneurs who collect several big industrial or commercial users. The respondents bid the number of hours a month that an aggregator group would promise to curtail, if the ISO called for interruptible load during or after a Stage 2.

The ISO would pay the participants a monthly reservation payment and also for each megawatt hour curtailed.

“The source of funds would be a charge to all load across the control area,” says Dozier.

The ISO is also proposing a “discretionary load curtailment program,” which would allow aggregators to post in a transparent internet type setting how much they will pay to curtail load in the real time market.

The cost of the curtailments would be spread among the remaining load.

Dozier says the ISO is working with the PUC to come up with a mechanism to continue the existing interruptible programs, too. He says there is a need for all the programs because of the supply shortages expected this summer.