By Tom Kleckner
ERCOT said an “exceptional” response by generators and a lack of extreme temperatures helped it meet record demand this summer without issuing alerts or calling for conservation measures.
ERCOT’s summer performance review said the wholesale market “performed as expected,” with generators responding to higher price signals and making their units available during peak demand periods. It noted the market “is designed to provide financial incentives to encourage market participants to respond appropriately” under tight operating conditions.
The ISO, which manages 90% of the state’s grid, set a new system demand peak of 73.3 GW on July 19, more than 2 GW higher than the previous record set in August 2016. The record high was one of 14 set during the lone period of extreme heat this summer (July 18-23).
ERCOT also set a new weekend peak demand of 71.4 GW on July 22.
The summer — which ends Sept. 30 for ERCOT — was the fifth hottest on record across Texas. However, high temperatures were “not as significant or as sustained” as they were during the 2011 record-setter, the ISO said. Temperatures averaged 86.7 degrees F during the summer, with Austin recording 90 days over 100 and Dallas 71 (including 40 consecutive).
Real-time system-wide wholesale prices ranged from $33/MWh to $47/MWh between June and August, with a high of $3,125/MWh on June 5. The highest system-wide price for a single settlement interval during July’s extreme weather came on July 18, when prices hit $2,169/MWh.
The highest system-wide day-ahead price was $2,062/MWh on July 23.
The ISO had fewer reliability unit commitments in 2018 compared to last year because market participants made their units available during tight system conditions, according to the review.
Generation outages were also half of what was projected in ERCOT’s final seasonal assessment in April, the grid operator said. (See ERCOT Gains Additional Capacity to Meet Summer Demand.) Outages and de-rates totaled a little over 2 GW during the July 19 peak.
ERCOT entered the summer with a planning reserve margin of 11%, almost half of that in previous years. The tightest operating conditions came on Aug. 18, when two large generators tripped, one just before the day’s peak. The ISO relied on operating reserves to meet demand “with no reliability concerns.”
ERCOT filed the report and accompanying data on Monday afternoon with the Texas Public Utility Commission, which has opened a docket on the summer’s market performance (Project 48511).
The ISO’s staff will also share their findings with stakeholders during the Technical Advisory Committee on Wednesday and the Board of Directors on Oct. 9.
