A CPS energy power line borders Rancho Sierra and other ranches adjacent.
A CPS energy power line runs through northwest Bexar County. Credit: Bonnie Arbittier / San Antonio Report

With Texas’ grid operator predicting record electricity demand this summer, San Antonio will do more than its share to put enough power on the grid, CPS Energy officials said.

This week, officials with the Electric Reliability Council of Texas (ERCOT) announced that the state’s reserve margin – the amount of electrical capacity available beyond predicted demand – would be 11 percent.

That’s better than ERCOT’s predictions earlier this year, but still down from last year’s margin of 16.9 percent. The smaller margin is largely the result of three coal plants in Texas closing in late 2017, ERCOT and state officials have said.

Grid operators like ERCOT strive to maintain a certain amount of reserve capacity to avoid people losing power and prevent extreme price fluctuations. This summer’s forecast put ERCOT’s reserve margin below its target of 13.75 percent.

Of that reserve margin, 18 percent will come from CPS Energy, San Antonio’s municipally owned electric and gas utility, officials said at its April meeting.

By comparison, CPS Energy customers only account for 7 percent of ERCOT’s demand, CPS Energy Chief Operating Officer Cris Eugster said.

“We are contributing to the state in terms of reliability and making a difference in terms of keeping the lights on,” Eugster told the utility’s board on Monday.

These forecasts piqued the interest of San Antonio Mayor Ron Nirenberg, a CPS Energy board member in his official capacity.

At the meeting, he drew a distinction between San Antonio and other cities that have promised to buy as much renewable power as possible but don’t actually generate that power themselves.

“I see many cities rushing to declare total resiliency, but we’re the ones that have been bearing the burden of the real energy production in Texas,” Nirenberg said.

Unlike some electric utilities that buy all their power off the grid, CPS Energy makes money both by supplying electricity to its roughly 736,000 customers and by selling power onto the grid from its portfolio of power plants, wind turbines, and solar arrays.

CPS Energy’s generating mix in 2017 was roughly 45 percent natural gas, 22 percent wind and solar, 18 percent coal, and 14 percent nuclear.

CPS Energy officials say its generating assets help insulate customers from high or variable prices, something ERCOT officials and state regulators are predicting for the summer.

“These are classic economic principles,” said DeAnn Walker, chair of the State’s Public Utility Commission, at a State Senate hearing on the issue Tuesday.

“You have less supply and more demand, and therefore, there will be higher prices this summer,” she said.

With weather forecasters predicting a hotter-than-average summer across the state, ERCOT analysts expect a record demand this summer of 72,756 megawatts, more than 1,600 megawatts higher than the record set in August 2016.

One megawatt can power roughly 500 homes, Eugster said.

Besides power plants and renewable sources, CPS Energy has programs that allow it to cut back on up to 212 megawatts of demand in its own territory when times are tight.

These include its commercial demand response program, which gives companies an incentive to cut their use at key times.

Its residential thermostat program also gives customers $85 bill credits for allowing CPS Energy staff to remotely adjust the temperature in their homes during peak energy times via WiFi thermostats.

Brendan Gibbons is a former senior reporter at the San Antonio Report. He is an environmental journalist for Oil & Gas Watch.