A presentation given by ERCOT officials on Monday warned that a combination of sustained high electricity demand and a high number of power plants going offline for unplanned maintenance could lead to a Level 1 Energy Emergency.
A day later, Texas’ main grid operator issued just such a warning as record temperatures drove up demand to a new record and some 3,000 megawatts of generation capacity was out of service for unexpected issues.
The presentation was given during a web-based meeting of ERCOT’s Generation Adequacy Task Force, one of several technical groups made up of officials from ERCOT, power plant operators, local utilities and other industry participants.
The discussion was about differences between ERCOT’s Capacity, Demand and Reserves Report from the beginning of summer and situations that occured on two days earlier this summer — June 27 and July 14 – when ERCOT asked consumers to conserve power during peak hours.
The reserve scenario predicted in the earlier report is one created for long-range planning and not meant to reflect the day-to-day reserves situation that ERCOT faces. But the presentation pointed out some key issues that seem to be of concern.
The earlier prediction expected peak demand to be just 63,898 megawatts, even less than last summer’s record-breaking peak, based on expected weather and economic demand projections. It also expected to reserve margins — the difference between the electric demand and electric generation capacity — to be 17.5 percent.
On June 27, the reserve margin was 6.6 percent while the margin on July 14 was 5.7 percent.
Some of the differences between expectations and reality? The number of megawatts provided by “Private Networks” — industrial sites like refineries or chemical plants that generate their own power and sell excess power onto the grid — was less-than expected on both days. There was about 1,000 megawatts less on June 27 and 1,500 megawatts less on July 14. (see the graphic)
Also, the number of plants either offline or running at reduced capacity because of maintenance was larger than expected. On June 27, nearly 5,000 megawatts were down for unplanned maintenance and on July 14 about 5,046 megawatts.
Production from wind turbines on both days was more than previously expected, however.
The Generation Adequacy Task Force isn’t charged with looking at power demands and capacity in ERCOT on a day-to-day basis. Rather, it looks at long-term issues and how to improve those forecasts.
But the final bullet point in the presentation on Monday was telling, given the events on Tuesday:
“If in the next month the current Resource Forced Outage/Derate of capacity continues and ERCOT experiences loads above 66,500 MW then ERCOT would possibly be in an Energy Emergency Alert (EEA) level 1 or higher.”
Tuesday and Wednesday saw new records for demand and about 3,000 megawatts and 4,000 megawatts of power plant capacity offline respectively. In an interview with reporters on Tuesday Kent Saathoff, ERCOT’s vice president of system planning and operations, said that wasn’t unusual for a typical summer day.