ERCOT expects Texas electric grid to hold up strong in fall, winter


A map of Texas showing the state s transmission lines is a focal point in the control room of the Electric Reliability Council of Texas, which operates most of the state's power grid. (Ryan Holeywell/Houston Chronicle)
A map of Texas showing the state s transmission lines is a focal point in the control room of the Electric Reliability Council of Texas, which operates most of the state’s power grid. (Ryan Holeywell/Houston Chronicle)

Following a summer of record heatwaves, Texas’ electric grid should hold up well during the upcoming fall and winter months, according to the agency that manages more than 85 percent of the state’s grid.

The Electric Reliability Council of Texas’ seasonal assessments and early outlooks for October through February project Texas’ grid will maintain at least 3,500 megawatts of reserve power even in the most extreme peak demand and power station outage scenarios. A megawatt powers about 200 typical Texas residences during peak demand.

ERCOT issued conservation alerts in August when reserves dipped below 2,500 megawatts during a time of 100-degree heat, power station outages and negligible wind production. The most recent peak demand record was set on Aug. 10 at 69,621 megawatts, ERCOT said, revising the figure downward from the original estimate of 69,783 megawatts.

“Based on our most extreme scenario, we expect to have sufficient capacity,” said Pete Warnken, ERCOT manager of resource adequacy, about the fall and winter months.

Fall officially begins on Sept. 23, but the council’s assessment starts with the beginning of October. Its projections are based on average weather patterns from 2002 through 2013 with extreme conditions scenarios built in.

“We have seen some unusual weather patterns associated with warm ocean temperatures, but I currently expect somewhat average weather this fall, with the possibility of below-normal temperatures and above-normal precipitation in most of the state,” ERCOT Senior Meteorologist Chris Coleman said in a statement.

In a conference call, Coleman said the El Niño weather event could be the strongest since 1997. For much of Texas, that could mean colder, rainier and cloudier winter days, but evenings without as much “bitter cold,” he said.

The El Niño system also could contribute to more wind power generated within the grid during the winter months, Coleman said.

With a new natural gas-fired power plant and three wind projects — a few other wind projects were delayed — added to the generation mix, ERCOT is expecting to have 77,289 megawatts of resources in the fall and 78,253 megawatts in the winter. Peak demand is projected at 49,709 megawatts in the fall. In a circumstance of demand coming in much higher, along with power plant maintenance outages and extreme forced outages, ERCOT still expects to have 3,606 megawatts in reserve.

Likewise, the early outlook on the winter projects peak demand of 57,400 megawatts, which would still leave about 3,600 megawatts in reserve during extreme scenarios. The all-time winter peak demand record of 57,265 megawatts was set in February 2011 and nearly matched in January 2014.

One megawatt of demand is typically enough to power about 500 homes during mild weather conditions and about 200 homes during summer peak demand, according to ERCOT.

Power generators typically schedule maintenance outages during the fall and spring to prepare for more extreme weather and demand in the winter and summer. It is typical for more than 9,000 megawatts to be voluntarily taken offline for maintenance during the fall.