Texas power grid still standing after onslaught of heat
The Texas electric grid held firm last week as power plants strained under summer workloads, a windless heat wave kept wind turbines idle and record demand underscored the challenges the state’s growing population presents to power managers.
Electricity demand at peak periods during a string of 100-degree afternoons pushed the grid near its generation capacity and led to officials’ requests for conservation. But the lights and air conditioners stayed on, according to the Electric Reliability Council of Texas that manages more than 85 percent of the state’s grid.
With the grid already stressed starting in late July, Texas peak demand, which typically occurs in later afternoon on hot summer days, set records three times
in early August.
The most recent peak demand was 69,783 megawatts on Aug. 10. One megawatt can power about 200 Texas residences during peak demand, ERCOT says.
Although demand didn’t hit records again, continuing hot weather during the week prompted a rare conservation statement on Aug. 12, as Gov. Greg Abbott urged Texans to curb their power use.
ERCOT issued a conservation alert on Aug. 13 with the peak electricity demand surging yet again and reserve capacity falling below the grid manager’s preferred 2,500-megawatt margin.
The strain on the grid was the most since the blistering summer of 2011, said Bill Blevins, ERCOT manager of operations planning.
“It did get pretty tight,” Blevins said. “But, overall, I think it was a pretty good performance.”
Operations last week also provided ammunition for critics who contend that wind energy isn’t reliable as a central component of power generation.
Texas leads the nation in wind capacity, at 13,000 megawatts, and wind turbines last year contributed more than 10 percent of ERCOT’s total power supply.
Throughout the Aug. 10 business week, however, wind power never contributed more than 3 percent of the power during the peak load. When demand peaked around 4 p.m. on Aug. 13, wind power accounted for less than 1 percent of the total power supply.
“It’s the Polyanna solution of wind power,” said Ed Hirs, a University of Houston energy economist who also is in the oil and gas business. “It gets really hot when it doesn’t blow as much.”
ERCOT acknowledges that wind power is often
weakest at the hottest times of Texas summer days. But Blevins said ERCOT has gotten better in recent years at predicting how much wind generation to expect each day and allocating resources accordingly.
If wind power is weaker than expected, more quickstart, gas-fired generation can start up on short notice, Blevins said.
As wind turbines stood becalmed last week, however, some fossil fuel plants went offline too. Those outages were more extensive than forecast, but still manageable, Blevins said.
Brett Kerr, spokesman for Houston-based Calpine, which owns and operates gas-fired power plants in
Texas, said 6 percent of the gas and coal plants had outages the week of Aug. 10, but that none of Calpine’s plants shut down.
The record demand during the hot spell, however, was a reminder of the longer-term dilemma for the Texas grid — growing population at a time when generating companies are retiring older power plants and building fewer new ones.
“This is not a surprise. The infrastructure is getting older and it’s not getting replaced,” Hirs said.
Hirs said proposed federal regulations on carbon emissions will lead companies to shut down more power plants rather than bear the costs of upgrades
necessary to meet the standards. And the economics of replacing them may not justify the investment.
ERCOT spokeswoman Robbie Searcy said 21,000 megawatts of power generation growth is in the works for the state, including more wind and solar power.
Chicago-based Exelon Corp. is adding 2,000 megawatts in natural gasfired power in the Houston and Dallas regions, while Dallas-based Panda Power Funds just announced it is expanding the capacity of its Sherman gas-fired power plant by 450 megawatts.