Energy Emergency Alert (EEA) UPDATE F EBRUARY 8, 2011

2 Summary of February 02, 2011 Event At midnight, ERCOT had planned generation availability of 61,351 MW. EEA Level 2A issued when reserves dropped below 1,750 MW at 5:20 AM. 77 generators had tripped/did not come online prior to the 10 AM morning peak load. EEA Level 3 issued at 5:43 AM for 1,000 MW firm load shed; total of 4,000 MW firm load shed by 6:23 AM. Final Firm Load restoration ordered at 1:07 PM. Load Resources recalled at 1:57 PM. New winter peak record set in the evening, 56,334 MW (integrated hourly average). EEA Level 2A ended & Emergency Interruptible Load Service (EILS) recalled on February 3 at 10 AM. ERCOT Public08 February 2011

Dallas Houston Austin Average Daily Temperatures for January and February, 1996 thru Feb 2, 2011 deg F count deg F count Feb 2011 Jan 2010 Jan 2010 and Feb 2011 Feb 2011 Jan 2010

4 Pre-Event Preparation J AN 28F EB 1 Jan 31 at 4:25: Requested MCSES 8 to be on-line by 10:00 on Feb 1; this generator has a long start-up lead time. Jan 31 at 10:30: Requested LHSES 1 on-line burning oil. Jan 28-31: Transmission outages – cancelled, withdrawn or delayed kV lines kV lines 3-69 kV lines 2-345/138 kV autotransformer 1-138/69 kV autotransformer Jan 31 at 6:30: Operating Condition Notice issued, “A cold front is approaching with temperatures anticipated to be in mid to low 18 degree range and maximum temperature expected to remain near or below freezing impacting 50% of more of major metropolitan areas. Estimated starting time Tuesday 2/1/11 09:00”. Feb 1 prior to midnight: 13 Generating Resources were committed in the Reliability Unit Commitment process. Feb 1 at 09:05: Advisory issued, expecting temperatures in teens to low 20F; maximum temperatures near or below freezing impacting 50% or more of major metro areas. 08 February 2011

5 Event Timeline – February 02, 2011 F EB 2 F EB 3, 10 AM EEA 2A ENDS & EILS RECALLED 4:30 1,804 MW Non-Spin deployed Issued Watch Reserves below 2,500 MW Issued EEA 2A Reserves below 1,750 MW Load Resources deployed Issued EEA 3 Firm Load Shed 1,000 MW 5:44 EILS deployed 7:57 Restored 500 MW (3,500 MW out) 8:22 Restored 500 MW (3,000 MW out) 9:25 Restored 500 MW (2,500 MW out) 5:43 5:20 6:04 Firm load shed 1,000 MW (2,000 MW total) 6:05 Frequency Hz 6:23 Firm Load Shed 2,000 MW (4,000 MW total) 6:59 Media Appeal issued 13:07 Restored 500 MW Restoration Complete Move to EEA 2B From EEA 3 New winter Peak Record 56,334 MW (Integrated ), 56,480 MW (Instantaneous). 14:01 5:08 11:39 Restored 500 MW (2,000 MW out) 12:04 Restored 500 MW (1,500 MW out) 12:25 Restored 500 MW (1,000 MW out) 12:49 Restored 500 MW (500 MW out) 13:57 Load Resources Recalled Move to EEA 2A From EEA 2B 15:14 19:15 08 February 2011

6 ERCOT Load Curtailment to manage Grid Security 08 February 2011

7 Forced Generation Outages ERCOT Public Note: Values represent cumulative forced outage capacity for each day. 08 February 2011

8 Outaged Generation ERCOT Public08 February 2011

9 Planned Generation Minus Outaged MW vs. Load Forecast at Midnight 08 February 2011