The upcoming winter season projects to bring with it a low risk to reliability in the PJM and MISO footprints under a more typical electric demand forecast, but reliability could be challenged in certain more extreme scenarios, according ReliabilityFirst (RF) analysis.  

Using data provided by both PJM and MISO, we perform our annual winter reliability assessment using two types of analysis:  

1. The 50/50 demand forecast, which projects a 50% likelihood that electricity demand exceeds projected load. This scenario is considered more likely to occur. 
2. The 90/10 demand forecast, which projects a 10% likelihood that electricity demand exceeds extreme load. This scenario is considered more extreme. 

Taken together, the two analyses paint the picture of how likely PJM and MISO each are to experience generation unavailability for the upcoming winter season¹.

PJM 

PJM’s 50/50 demand forecast projects its footprint to have adequate resources to serve normal electric demand in the upcoming winter season, including during expected periods in which certain generation resources become unavailable. PJM’s planning reserve margin requirement is 30% for the 2024 planning year, and its forecasted reserve margin comes in above that figure at 40.6%.   

Exhibit 1 shows PJM’s winter outage likelihood based on different generation outage levels², with the two yellow dots showing winter outage probability in the 50/50 demand forecast and the 90/10 demand forecast.

The vertical axis indicates the percent probability, and the horizontal axis shows the outage total in megawatts.

For 50/50 load, 45,000 MW of generation unavailability may require operator mitigating actions. This analysis, marked by the yellow dot at the far right, indicates that there’s a very low likelihood of this amount of generation outages occurring, making PJM a low risk for the upcoming winter, as stated above.

Should the system encounter a scenario in which there is a combination of higher demand and/or generation outages that is above anticipated levels, PJM projects to still be at low risk for the upcoming winter season, as shown in Exhibit 1 by the yellow dot on the left marking the 90/10 demand forecast.

MISO

MISO’s 50/50 demand forecast also projects its footprint to have adequate resources to serve normal electric demand in the upcoming winter season, including during expected periods in which certain generation resources become unavailable. MISO’s planning reserve margin requirement is 49.5% for the 2024 planning year and its forecasted reserve margin is also above that figure at 55.1%.

Exhibit 2 shows MISO’s winter outage likelihood based on different generation outage levels, with the two yellow dots showing winter outage probability in the 50/50 demand forecast and the 90/10 demand forecast.

For 50/50 load, 40,800 MW of generation unavailability may require operator mitigating actions. This analysis, marked by the yellow dot on the right, indicates that the likelihood of this amount of generation outages occurring in the MISO footprint is low, as stated above.

However, should the system encounter a scenario in which there is a combination of higher demand and/or generation outages that is above anticipated levels, MISO projects to be at an elevated risk for the upcoming winter season, as shown in Exhibit 2 by the yellow dot on the left marking the 90/10 demand forecast. In this case, MISO plans to maintain reliability through various operator intervention mechanisms³.

Other considerations

Separate from the above analyses, RF also examined a third scenario specific to PJM. In the PJM footprint there exists a reliability risk involving potential constraints on the use of the Transco Regional Energy Access (REA) gas pipeline due to ongoing litigation contesting its use. PJM supports usage of the pipeline to its full capability, however several states and environmental groups are challenging the Federal Energy Regulatory Commission (FERC)’s approval of the project in court. RF analysis indicates that under extreme outages and demand in PJM, if the Transco REA gas pipeline is not in service there is a risk of load not being served.

 

Footnotes:

1. These projections use historical Generator Availability Data System (GADS) data from a rolling five-year period, which provided a range of outages that occurred during the winter period (i.e., December through February) of 2020 through 2024 and outages that occurred during daytime operations (note: the distribution of random outages used for this assessment is not linear throughout the range of outages observed).

2. When reviewing Exhibits 1 and 2, the outage total across the horizontal axis of the graph is the number of outages that could occur during the timeframe examined based on historical GADS data. The probabilities on the vertical axis are not based on a true statistical analysis of the available daily random outage data. Instead, these values represent the proportion of outages compared to the total resources available, then determines how often this proportion occurred within the five-year historical winter period.

3. These include: Load Modifying Resources (aka demand response), non-firm energy transfers into the system, energy-only resources, internal transfers that exceed the Sub-Regional Import/Export Constraint (SRIC/SREC) between the MISO North/Central and South regions.