Above-average temperatures this summer will increase the risk of electricity emergencies in the West, especially Texas and California, and challenge reliability in the Upper Midwest and New England, according to the nation’s grid watchdog.

The North American Electric Reliability Corp. in its “2021 Summer Reliability Assessment” predicts extreme heat will drive demand nationwide and elevate the potential for power disruptions as air conditioning use chomps electricity.

Texas in particular will be ripe for shortages despite increasing its on-peak reserve margins from 12.9% to 15.3% last year with 7,858 megawatts of wind, solar and battery storage, NERC said. The assessment notes that “[with] a significant portion of electricity supply coming from wind generation, operators must have sufficient flexible resources to cover periods of low-wind output.”

NERC also finds California, a huge energy importer, at risk for disruptions this summer even during normal peak demand periods as additions to its energy supply have largely been solar, which may not be available to serve heightened demand. Periods of above-normal demand in the West will place the state at a high risk for energy emergencies, the report states.

“As the grid transforms and weather-dependent resources become increasingly important to maintaining the real-time supply for electricity, the bulk power system becomes more vulnerable,” said John Moura, NERC director of reliability assessment and performance analysis.

“Above-average seasonal temperatures, such as those predicted for this summer, can contribute to high peak demand and impact the availability of generation resources and imports from neighboring areas,” he said. “This means that it is especially important for the electric industry to ensure the committed resource mix can support a variety of abnormal conditions.”

NERC said the Midcontinent Independent System Operator in the Midwest and ISO-New England have sufficient resources to meet projected peak needs, but above-normal demand will likely outstrip capacity. That means supplies will need to be tapped from outside areas.

“All other areas have sufficient resources to manage normal summer peak demand and are at low risk of energy shortfalls from more extreme demand or generation outage conditions,” the assessment said.