A Coordinated Electric System Interconnection Review—the utility’s deep-dive on technical and cost impacts of your project.

Challenge: Frequent false tripping using conventional electromechanical relays
Solution: SEL-487E integration with multi-terminal differential protection and dynamic inrush restraint
Result: 90% reduction in false trips, saving over $250,000 in downtime

Each year, the North American Electric Reliability Corporation (NERC) publishes its Winter Reliability Assessment (WRA) to evaluate whether the Bulk Power System (BPS) can reliably meet electricity demand during the winter season. The 2025–2026 Winter Reliability Assessment is particularly important because it reflects a power system undergoing rapid transformation. This includes rising winter demand, accelerated electrification, large data-center load growth, the retirement of conventional thermal generation, and increasing reliance on inverter-based resources (IBRs), battery energy storage systems (BESS), and demand response programs.

While these resources provide important flexibility and decarbonization benefits, they introduce new operational and planning challenges:

Solar output is minimal during winter peak hours, which often occur before sunrise or after sunset
Wind output can be highly variable during extreme cold weather
Battery systems are energy-limited and depend on state-of-charge management during multi-day cold events
Demand response is constrained by contractual limits on duration and frequency of use

From an engineering standpoint, this means capacity adequacy alone is no longer sufficient energy adequacy, endurance, and fuel security must also be evaluated.

Natural-gas-fired generation continues to play a critical role in meeting winter peak demand across much of North America. However, the WRA again highlights gas-electric interdependencies as a dominant winter reliability risk:

Gas production and delivery infrastructure is vulnerable to freeze-offs during extreme cold
Many generators rely on non-firm gas transportation, increasing curtailment risk
Misalignment between gas and electric market timelines complicates fuel procurement
Natural gas infrastructure winterization remains largely voluntary outside of Texas

Although improvements have been observed since Winter Storms Uri and Elliott, fuel assurance remains one of the most consequential winter reliability challenges.

The WRA assesses each NERC region using Anticipated Reserve Margins (ARM), deterministic stress scenarios, and probabilistic risk metrics such as LOLH and EUE. While all regions are adequate under normal conditions, several areas face elevated risk under extreme cold scenarios:

ERCOT (Texas): Continued exposure to reserve shortages during extreme winter conditions, despite improved winterization and growing battery deployment
NPCC-Maritimes: Reserve margins below reference levels under certain scenarios, with likely reliance on emergency operating procedures
SERC-East and SERC-Central: Transitioning toward winter or dual-peaking behavior due to electrification trends
WECC-Basin and WECC-Northwest: Increased reliance on imports during extreme cold, which may not be available during wide-area events

For these regions, engineering preparedness and operational readiness are critical risk mitigators.

A major development reflected in the 2025–2026 WRA is the implementation of enhanced cold weather Reliability Standards. In late 2025, FERC approved updates to EOP-012, establishing enforceable requirements for:

Generator freeze protection measures
Cold weather preparedness plans
Corrective action tracking
Operator training and readiness

Initial data indicates that the vast majority of winter capacity can operate at or below defined Extreme Cold Weather Temperatures (ECWTs). This represents a meaningful improvement in baseline winter readiness, but compliance effectiveness will depend on robust engineering implementation, documentation, and ongoing verification.

What is the purpose of NERC’s Winter Reliability Assessment?
The WRA evaluates whether the Bulk Power System has sufficient resources and operational flexibility to meet winter peak demand under normal and extreme weather conditions. It identifies regional risks, emerging trends, and areas requiring heightened preparedness.
Why is winter reliability becoming more challenging than in the past?
Winter demand is increasing due to electrification and data centers, while the resource mix is shifting toward variable and energy-limited resources. At the same time, fuel supply risks—especially for natural gas—remain significant during extreme cold events.
What are Anticipated Reserve Margins (ARM)?
ARM represents the percentage by which anticipated resources exceed forecast net internal demand under normal peak conditions. It is a core metric used to assess resource adequacy.
Why can regions with high reserve margins still face reliability risk?
Reserve margins are calculated under normal assumptions. Extreme cold, correlated outages, fuel supply disruptions, and low renewable output can quickly erode available reserves.
How do batteries contribute to winter reliability?
Batteries provide fast-responding capacity and contingency support, but their contribution is limited by stored energy and recharge opportunities during prolonged cold events.
Why is natural gas such a critical winter reliability issue?
Natural gas supplies a large portion of winter generation, but it cannot be easily stored on-site. Freeze-offs, pipeline constraints, and non-firm contracts increase outage risk.
What are Energy Emergency Alerts (EEAs)?
EEAs are declared when a BA faces insufficient resources to meet demand and reserves. They range from EEA-1 (all resources in use) to EEA-3 (firm load shedding).
How does electrification affect winter peak demand?
Electrification of heating increases demand during cold mornings and evenings, shifting peak load from summer afternoons to winter risk hours.
What role does demand response play in winter reliability?
Demand response can reduce peak demand, but its availability is limited by contractual duration, notification requirements, and customer participation.
What is EOP-012 and why is it important?
EOP-012 is a NERC Reliability Standard focused on cold weather preparedness for generators, requiring freeze protection, planning, and training.

In 1995, Sandip (Sonny) R. Patel earned his Electrical Engineering degree from the University of Illinois, specializing in Electrical Engineering . But degrees don’t build legacies—action does. For three decades, he’s been shaping the future of engineering, not just as a licensed Professional Engineer across multiple states (Florida, California, New York, West Virginia, and Minnesota), but as a doer. A builder. A leader. Not just an engineer. A Licensed Electrical Contractor in Florida with an Unlimited EC license. Not just an executive. The founder and CEO of KEENTEL LLC—where expertise meets execution. Three decades. Multiple states. Endless impact.