Rare blackouts hit TX

Last week's rolling blackouts in Texas were the first in 17 years.

BY HEATHER MOYER | DALLAS, Texas | April 25, 2006

Last week's rolling blackouts in Texas were the first in 17 years for the Electric Reliability Council of Texas, and it was all caused by a spike in the weather during a time when extreme heat is not expected.

ERCOT is a non-profit organization regulated by the Public Utility Commission of Texas. According to the ERCOT website, "the organization is entrusted to keep electric power flowing to approximately 20 million Texas customers."

ERCOT Spokesperson Dottie Roark said her agency encourages its many power generating members to perform maintenance during April. "Summer is the peak time for us, so we encourage the maintenance work in April because of the cooler temperatures," said Roark.

Yet last Monday, many of ERCOT's customers coped with rolling blackouts due to unexpected hot temperatures.

Roark said the high on April 18 in Dallas was five degrees over the forecast, which caused a huge impact on the grid. "We don't expect temperatures in the 100s at this time, that's why we were short of capacity," she explained. In fact, she said it was a series of events that prompted the involuntary rolling blackouts - something the agency hasn't had to enact for 17 years.

"We do have an electric energy curtailment program and that's what we focused on last Monday," she said, noting the agency's plan for when events like last Monday's happen. Roark said the demand reached a high point last Monday at 12pm, so the agency went to the first step of their emergency plan. "We call in all available capacity. We did that in 2003 during an ice storm and that solved the problem. Yet this time it was still getting hot so we went to step 2 - bringing in the interruptible loads."

"Interruptible loads" is the term for those power generators who have signed a contract with ERCOT to move their loads to ERCOT's if their power is needed.

"Yet then around 4pm we had several units (fail) within a few minutes of each other," said Roark. "That's when our frequency went below a certain cycle. That triggers step 4 - rolling outages."

The failing units caused the process to immediately skip step three of notifying the public to conserve energy before outages were needed. Roark said that move may have inconvenienced some people, but in reality the power operators did the right thing.

"They saved the state from what could have been a really extended sustained blackout which would have cost money and lives. Thank goodness we had our emergency procedure in place to avoid a blackout."

Now ERCOT staff are reviewing lessons learned from last Monday's emergency to see how to avoid it in the future.

This week's temperatures in Texas are forecast to be slightly cooler.

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Related Links:

Electric Reliability Council of Texas


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