ERCOT Not Anticipating Rolling Blackouts for Tuesday

Voluntary Conservations Efforts Encouraged as Heat Wave Continues

Austin, April 18, 2006 – The Electric Reliability Council of Texas (ERCOT) anticipates adequate generation for today's electricity demand -- barring unforeseen circumstances -- but is still asking Texas electric consumers to conserve electricity during peak hours due to the continuing high temperatures.

ERCOT Operations is forecasting a peak load of approximately 53,000 megawatts today, and generation scheduled to be available is about 58,000 MW.

Additional generation was brought on line today by delaying some scheduled maintenance outages.  Additionally, some units that were out for maintenance were able to come back online.

Due to the continuing high temperatures, Texas electric consumers are still encouraged to continue to conserve electricity when possible particularly during the critical peak hours of 3 p.m. to 7 p.m.

Summary of Events - April 17, 2006

Peak load forecast – 49,018 MW
Peak capacity scheduled – 53,920 MW
Capacity out for scheduled maintenance – 14,000 MW
Hour ending 3:00 pm demand was 50,265 MW

At 3:25 pm Step 1 of the emergency electric curtailment plan (EECP) was declared:

• All balancing bids and regulation being used
• Spinning reserved deployed
• Difficulty maintaining 60 Hz
• Asked for all capacity available to be brought on line and generating
• Scheduled emergency assistance over the DC ties

At 3:34 pm EECP Step 2 declared

• Continued low frequency with all balancing and regulation deployed
• Deployed all LaaRs (interruptible loads providing Responsive Reserve – 1,150 MW)
• Frequency recovered to 60 Hz

Hour ending 4:00 pm load was 51,714 MW

• Shortly after 4:00 pm several units tripped within a few minutes of each other ~1,200 MW total
• Frequency went below 59.8 HZ

At 4:13 pm EECP Step 4 declared

• Ordered 1,000 MW firm load shedding
• Allocated to Transmission Operators on a load ratio share basis
• Rotated among customers

At 4:25 pm Step 3 of the EECP (Public Appeal for Conservation) was issued

Frequency recovered but balancing and regulation continued to be fully used until about 5:30 pm

At 5:31 pm ERCOT started reducing firm load curtailments

At 6:10 pm all firm load restored

At 6:21 pm started restoring LaaRs (interruptible) load)

EECP fully cancelled at 7:20 pm

*all numbers are preliminary

The ERCOT grid broke its all-time April peak demand record on Monday, with a preliminary estimate of 51,714 megawatts.  The all-time system peak is 60,290 megawatts, set last Aug. 23, during the traditional summer peak season when more resources are available.

ERCOT’s last use of the EECP was during the February 2003 ice storm.  The last time interruptible loads were curtailed was August, 1999.  The last time involuntary firm load shed occurred in the ERCOT region was December 22, 1989.