An estimated two-thirds of the people living across wide swaths of the United States and parts of Canada are facing elevated risks from “insufficient operating reserves” for power generation this summer, as extreme heat and maintenance disruptions breach an abundance of natural gas supply, according to the North American Electric Reliability Corp. (NERC).

In its 2023 Summer Reliability Assessment, NERC found “no high-risk areas” but “the number of areas identified as being at elevated risk has increased.”

Natural gas-fired generation remains key to ensuring grid reliability, said NERC’s Mark Olsen, who manages Reliability Assessments. Even as more renewable energy resources come online, gas-fired generation balances the grid because of the intermittency of wind and...