The North American Electric Reliability Corporation (NERC) is responsible for reducing risks to the reliability of the electric power grid in the U.S., Canada, and a tiny part of Mexico. NERC is overseen by the Federal Energy Regulatory Commission. Each year, NERC assesses developments and risks that could impact electricity supplies for the summer and winter peak demand periods. NERC also investigates and analyzes the causes of power system disturbances, such as problems during extreme weather.
A few days ago, NERC released its Winter Reliability Assessment (WRA) for the upcoming winter period which is defined as December 2023–February 2024. The WRA designated almost half the U.S. as being at an “elevated risk” of having insufficient operating reserves during extreme weather. Operating reserves are electricity supplies that are not being used but can quickly come online in the case of an unplanned event such as an equipment malfunction or fuel supply disruption. The first finding in last year’s WRA (2022-2023) and this year’s (2023-2024) are exactly the same: “A large portion of the North American BPS is at risk of insufficient electricity supplies during peak winter conditions.” However, the area at risk for electricity shortages is larger this year than last year.
The new WRA includes a number of findings. Two of the findings are summarized briefly below with excerpts from the reliability assessment. (We encourage readers of this blog to read the WRA to better understand the assessment and its nuances.) Because the assessment highlights significant risks associated with natural gas, we include the dependence of certain regions on natural gas.
“… an extreme cold-weather event that extends into MISO’s southern areas can cause high generator outages from inadequate weatherization or insufficient natural gas fuel supplies. Load shedding is unlikely but may be needed under wide-area weather events.” (Load shedding means cutting off power to parts of the grid until electricity demand and supply are balanced. It also protects the grid from damage that could cause long-term interruption of power supplies.)
According to NERC, natural gas contributes 46% of MISO’s winter resource mix.
“Potential constraints on the fuel delivery systems and the limited inventory of liquid fuels may exacerbate the risks for fuel-based generator outages … that result in energy emergencies during extreme weather … A standing concern is whether there will be sufficient energy available to satisfy electricity demand during an extended cold period given the existing resource mix, fuel delivery infrastructure, and expected fuel arrangements without considerable effort to replenish stored fuels (i.e., fuel oil and liquified natural gas).”
Natural gas contributes 54% (17 GW) of New England’s winter electricity resource mix.
PJM and parts of the Southeast
“A severe cold weather event … can lead to energy emergencies … Forecasted peak demand has risen while resources have changed little in these areas since Winter Storm Elliott … [The generators in these regions] are vulnerable to derates and outages in extreme conditions … A severe cold weather event that extends to the South can lead to energy emergencies as operators face sharp increases in generator forced outages and electricity demand.”
Natural gas contributes 47% (85 GW) of PJM’s winter resource mix and 44-51% (23-32 GW) for parts of the Southeast.
“ … the risk of a significant number of generator forced outages in extreme and prolonged cold temperatures continues to threaten reliability where generators and fuel supply infrastructure are not designed or retrofitted for such conditions. The risk of reserve shortage is greater than last winter due primarily to robust load growth that is not being met by corresponding growth in dispatchable resources … Electricity demand in Texas rises sharply as extreme cold temperatures add to winter operating challenges and energy shortfall risks …For the upcoming winter season, Texas RE-ERCOT will face reserve shortage risks during high net load hours … Load shedding is unlikely but may be needed under wide-area cold weather events.”
Natural gas contributes 62% (54 GW) of ERCOT’s winter resource mix.
Southwest Power Pool
“While the reserve margin is adequate for normal forecasted peak demand and expected generator outages, higher demand levels and outages that have occurred during extreme cold weather result in shortfalls that can trigger energy emergencies. The vast wind resources in the area can alleviate firm capacity shortages under the right conditions; however, energy risks emerge during periods of low wind or forecast uncertainty and high electricity demand … SPP does not anticipate any emerging reliability issues impacting the area for the 2023–2024 winter season but realizes that interruptions to fuel supply could create unique operation challenges.”
Natural gas contributes 41% (27 GW) to SPP’s winter resource mix.
“Recent extreme cold weather events have shown that energy delivery disruptions can have devastating consequences for electric and natural gas consumers … Winter Storm Elliott demonstrated the wide-area consequences for BPS reliability that can result from reduced natural gas production during periods of extreme cold weather …” NERC and FERC jointly recommended “establishing reliability rules for natural gas infrastructure …[and] control room to control room operational communications protocols that can be invoked when extreme weather approaches ….”
“Coal is an important fuel for electricity generation in winter. Generator owners report fewer coal supply issues compared to last winter. Normal rail transportation services are available and coal stocks are at a high level compared to historical averages. Some coal-fired generation that relies on barge shipments in inland waterways could be impacted by drought restrictions that limit barge loading.”
Final observation by America’s Power
Despite NERC’s continued warnings about the potential for electricity shortages, coal-fired generation continues to retire at an alarming pace. Based on announcements by their owners, more than 11,000 megawatts (MW) of coal will have closed during the time between these two winter assessments. In addition, almost 5,300 MW of coal are expected to shut down next year. Therefore, it is essential to take steps to ensure that coal retirements do not outpace the addition of resources that can provide the same attributes as coal. These include a high accredited capacity value (a measure of how dependable a resource is when electricity demand peaks), fuel assurance, and many other attributes.
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