ERCOT bracing for another tight summer

The Electric Reliability Council of Texas (ERCOT) warned that the summer of 2013 could be another summer of tight demand on the state’s electricity-generating resources, and advised consumers to be prepared for energy emergency alerts (EEA) and appeals to reduce energy use during the summer’s warmest weather.

In its seasonal assessment of resource adequacy for the summer, issued March 1, the grid operator said it expected generation reserves to be a little tighter this summer than last, and that the grid operator could see scenarios where the system would have insufficient resources available to serve customer demand.

“By the start of the summer, generation owners will have added about 1,000 MW of new generation resources since last summer,” Warren Lasher, ERCOT’s director of system planning, said during a media briefing. “But our expectation is that, because of population growth in the state and increased economic activity, that our peak loads are likely to grow around 1,200 MW to 1,400 MW.”

Those figures mean the system’s anticipated reserve margin will be 13.2%. ERCOT’s target is 13.75% reserve margin.

If the state experiences a typical summer, the grid operator expects there will be at least a few days where it has to call for customers conservation during the peak hours of the day, from approximately 3:00 p.m. to 6:00 p.m. However, if the region experiences a hot spell in August, such as it saw in the summer of 2011, or experiences an outage of one or more large generation units, the grid operator would initiate its energy emergency alert procedures, which could include rotating customer outages.

As with all such predictions, weather is a key factor.

“For the next two seasons, we’ll still forecasting above-normal temperatures and below-normal precipitation,” Chris Coleman, ERCOT meteorologist, said. “However, there are some exceptions and I don’t see it approaching the extremes of 2011,” when the region experienced prolonged heat waves.

The preliminary summer assessment anticipates a peak demand of 67,998 MW, based on a weather outlook similar to that of 2010 and a slower-growth economic outlook. ERCOT anticipates 73,708 MW of generation capacity before accounting for power plant outages, which typically total about 2,600 MW during an operating day. That generation includes Luminant’s Monticello units 1 and 2, which have a combined generating capacity of 1,070 MW, and which the operator said will be available for the summer season.

One megawatt can serve about 200 Texas homes during peak demand periods, ERCOT said, noting that power demands in its region are highest in summer, primarily due to air conditioning use in homes and businesses.

The report also referred to “more than 1,900 MW of additional capacity” that is currently mothballed, but which could be brought back on-line if necessary, given sufficient lead time. That additional capacity, ERCOT said, could be returned to service in less than four months.

Conditions would be exacerbated if the grid operator experiences a higher than normal number of forced generation outages occur during a period of high demand or if record breaking weather conditions similar to the summer of 2011 lead to even higher than expected peak demands. In such cases, EEA declarations could be followed by a need to institute rotating outages to maintain the integrity of the system as a whole, the grid operator said in its report.

Estimates of available capacity could be revised upward in the near future. Current estimates include wind power at 8.7% of its installed capacity, and ERCOT stakeholders are evaluating whether to recommend increasing that capacity value based on recent performance.

At the same time, ERCOT issued its seasonal assessment of resource adequacy for the spring, in which it said it expected to have sufficient installed generating capacity to serve forecasted peak demands with expected generation outages in the upcoming March through May season. As long as extreme weather well beyond expected conditions does not occur during the early part of the season when power plants are undergoing maintenance to prepare for summer, ERCOT does not anticipate having to issue EEAs during the spring of 2013, it said.

The ERCOT region’s all-time record peak occurred on Aug. 3, 2011, when consumer demand hit 68,305 MW. Although the summer of 2012 was much milder than the record-breaking conditions that marked the previous year, ERCOT still experienced new monthly peaks in June, July and September.

ERCOT will continue to assess conditions to determine if additional actions should be taken to help protect system reliability this summer, and will issue a final assessment for summer 2013 in May.