The North American Electricity Reliability Corporation has just issued its 2023–2024 Winter Reliability Assessment (WRA), which identifies, assesses, and reports on areas of concern regarding the reliability of the North American power system for the upcoming winter season.
This report looks at how supply challenges, especially in a cold winter, could have impacts across the continent. Many people will remember the Texas winter outages of a couple of years ago, and while some improvements have been made, it seems that insufficient preparation has been made in some sectors for potential severe weather events.
Key findings from the WRA, covering the main winter period (December–February), identifies some areas of serious concern and provides an evaluation of the generation resource and transmission system adequacy necessary to meet projected winter peak demands and operating reserves.
A large portion of the North American Bulk Power System (BPS) is at risk of insufficient electricity supplies during peak winter conditions. Prolonged, wide-area cold snaps threaten the reliable performance of BPS generation and the availability of fuel supplies for natural-gas-fired generation. As observed in recent winter reliability events, over 20% of generating capacity has been forced off-line when freezing temperatures extend over parts of North America that are not typically exposed to such conditions. When electricity supplies become constrained, BPS system operators can face a simultaneous sharp increase in demand as electric heating systems consume more power in cold temperatures. These areas are at greatest risk for electricity supply shortfalls this winter.
See this diagram: the red and orange areas will be at risk of outages if there are bouts of severe weather.
Over the past 11 years, five cold weather events have jeopardized Bulk Electric System (BES) reliability by triggering unplanned cold weather-related generation outages. To maintain BES reliability during Winter Storm Uri in February 2021 and Winter Storm Elliott in December 2022, BES operators were required to shed firm load. During both winter storms, numerous electrical and mechanical issues rendered significant portions of the impacted areas' thermal generation fleet unavailable while natural gas supply and transportation issues prevented numerous otherwise available natural-gas-fired generators from supplying much needed electrical energy. Moreover, a significant portion of generating units failed to perform at temperatures above their own documented minimum operating temperatures.
The report finds that much of North America is again at an elevated risk of having insufficient energy supplies to meet demand in extreme operating conditions. The areas identified as being at higher risk extend over much of the eastern two-thirds of the continent as shown above. In these areas, although resources are adequate for normal winter peak demand, any prolonged, wide-area cold periods will be challenging due to generator outages and fuel vulnerability, extreme levels of electricity demand, difficulties in accurate forecasting and the risk of firm electricity transfer curtailments.
There is a critical issue around the availability of natural gas supplies for power plants. During severe weather, generators can face operating problems due to low temperatures. Supplies of natural gas can be diverted towards residential heating; and gas production can slow down owing to pipeline and wellhead difficulties. This is going to increase the strain on the transmission network.
NERC’s recommendations for the cold months ahead include for reliability coordinators to monitor fuel adequacy, utilities to weatherize power plants and for balancing authorities to “pay particular attention to the risk of demand underestimation ahead of extreme winter conditions.” Nevertheless, it could be that utilities will face a tricky challenge if there is a cold winter.