Aggressive government climate-related infrastructure policies, more extreme weather and growing consumer demand for lower-emission energy are quickly changing the resource mix of the bulk power system and elevating reliability risks, according to the North American Electric Reliability Corp.

“Managing this pace of change presents the greatest challenge to reliability,” NERC said in its long-term reliability assessment released Dec. 17.

NERC identified significant reliability risks associated with more intermittent and distributed energy resources and inverter-based resources such as wind, solar and battery storage systems.

The report finds most regions are projected to have sufficient capacity to meet annual peak demand under normal weather conditions, but potential near-term capacity shortfalls may be caused by the retirement of coal-based generation facilities with no ready replacement. The Midcontinent Independent System Operator region, it said, could lose 13 gigawatts of resource capacity from plant retirements between 2021 and 2024.

“Capacity-based estimates, however, can give a false indication of resource adequacy. Energy risks emerge when variable energy resources (VER) like wind and solar are not supported by flexible resources that include sufficient dispatchable, fuel-assured, and weatherized generation,” the electric reliability organization said.

NERC also projected that increased variable resources this year will raise the risk of energy shortfalls, specifically 23 hours of load loss in the Northwest, and up to 10 hours of load loss in the California-Mexico region.

“Sufficient flexible resources are needed to support increasing levels of variable generation uncertainty.”

NERC notes that while natural gas generation could help sustain reliability, it will require better coordination between suppliers and grid operators.

“The natural gas system was not built or operated with electric reliability as the first concern,” the report states. “Electric grid planners must understand natural gas system vulnerabilities to assess contingencies and plan for grid reliability.”

Other key findings and recommendations include:

• An increase in stronger storms is “a core condition” for resource planning for reliability, which requires that capacity and its fuel must be “assured even in extreme weather.”

• To integrate IBRs, owners and operators must coordinate to accurately account for these new resources.

• DER aggregators will be increasingly important to the bulk power system in the coming years, and their participation in wholesale markets should be considered for potential impacts to reliability and mitigating risks.

NERC is charged with the security of the bulk power system and sets and enforces reliability standards. The organization also assesses trends, needs and remedies for grid reliability. It operates under the supervision of the Federal Energy Regulatory Commission.