According to the North American Electric Reliability Corp.’s 2024 Summer Reliability Assessment, released in May, while some areas now have reduced risk of supply shortfalls, thanks to the addition of resources, a considerable portion of the continent remains at risk.

Causes of risk include heat events that affect generation, wind output or transmission systems, and increased demand. The assessment found a significant increase in demand, particularly in the Southwest, Texas and British Columbia, and “elevated risk” of energy emergencies during extreme conditions for seven areas (Midcontinent Independent System Operator, MRO-SaskPower, NPCC-New England, Texas RE-ERCOT, WECC-British Columbia, WECC-California/Mexico and WECC-Southwest).

“Demand is growing in many areas at a rapid pace with the adoption of electric vehicles and construction of new data centers, straining some parts of the system,” said Mark Olson, NERC’s manager of reliability assessments.

The combination of demand growth, extreme weather events, recent generator retirements, wind turbine performance, drought and unplanned outages may be the cause of insufficient reserves.

While all areas have enough supply for normal peak load, thanks to 25 gigawatts of additional solar capacity added since last year, some areas are facing increased risk due to low output of solar, wind and hydropower. Olson explained that the issue is being addressed in part by new firm transfer agreements, growth in demand response and postponed generator retirements.

“One of the key challenges operators face as the resource mix evolves is how to get through the summer evening periods with fewer available resources at their disposal,” said John Moura, NERC’s director of reliability assessments and system analysis. Risk of electricity supply shortages tend to occur in the late afternoon and evenings in areas such as Texas and California, where solar photovoltaic resources make up a large portion of the resource mix, because solar output is reduced, but demand remains high.

Although NERC does not predict bulk power system reliability issues this summer, the group continues to emphasize the value of coordinating gas and electric, particularly focusing on how natural gas infrastructure maintenance plans could affect generators.

Other reliability issues the assessment recommends addressing include the response by inverter-based resources to system disturbances, which affect solar facilities, battery storage and traditional generation.

With more reliance on variable energy resources, recommendations for those in elevated risk areas include ensuring that state regulators and the industry have protocols in place at the beginning of summer for managing requests from generators and be prepared to deal with potential supply shortfalls, as well as potential generation and transmission outages.

Michelle Bloodworth, president and CEO of America’s Power, issued a statement in response to the release of the assessment: “NERC’s latest reliability assessment shows that our electricity grid is becoming increasingly reliant on weather-dependent sources of electricity, leaving one-third of the country at elevated risk of blackouts this summer.”

She considers delayed coal plant retirements a temporary fix because “EPA regulations will cause more coal retirements that cannot be delayed. These regulations, especially the recently announced Carbon Rule, increase the chance of blackouts.”