July 18 (Reuters) - Texas homes and businesses set a power consumption record for July for a second day in a row on Tuesday and are expected to break the all-time peak over the next week as consumers crank up air conditioners to escape a brutal heat wave, according to the operator of most of the state's power grid.
To keep air conditioners humming, Texas utilities bought electricity from all sources, boosting power prices to their highest in almost seven years.
The Electric Reliability Council of Texas (ERCOT) said demand reached 70,963 megawatts on Tuesday, topping the prior monthly record of 70,587 MW on Monday. One megawatt can power about 1,000 U.S. homes.
Tuesday's peak was shy of the grid's all-time high of 71,110 MW in August 2016 and ERCOT's forecast high of 72,756 MW for this summer, but that is not expected to last long.
ERCOT predicted peak demand would break Tuesday's high every day over the next week, including Saturday and Sunday, when usage usually falls as businesses close for the weekend.
High temperatures in Houston were expected to reach 98-100 degrees Fahrenheit (37-38 Celsius) every day from July 16-24, according to AccuWeather.
The normal high in Houston, the fourth-largest U.S. city, at this time of year is 94-95 degrees F.
ERCOT forecast usage would reach an all-time high of 72,492 MW on Wednesday, followed by 74,620 MW on Thursday, 75,225 MW on Friday, 72,200 MW on Saturday, 72,145 MW on Sunday, 75,896 MW on July 23 and 75,016 MW on July 24 before easing to 73,059 MW on July 25.
Power prices in the ERCOT North hub EL-PK-ERTN-SNL jumped to $351.00 per megawatt-hour on Tuesday, their highest since August 2011. That compares with an average of $37.15 so far this year and $26.67 for all of 2017.
Despite the retirement of three big coal plants in early 2018, ERCOT has said it expects to have sufficient operational tools to manage tight reserves and maintain system reliability this summer.
Those tools include using a previously mothballed power plant, imports from other regions, consumer conservation and demand response efforts, which compensate consumers for cutting electric usage.
ERCOT manages the flow of electric power to 24 million Texas customers, representing about 90 percent of the state's electric load.
The biggest power utilities in Texas include units of Sempra Energy, CenterPoint Energy Inc, American Electric Power Co Inc, Entergy Corp and Xcel Energy Inc.
Reporting by Scott DiSavino; Editing by Bernadette Baum