The implications of temperature for power system reliability have not received widespread attention in electric power system generator resource adequacy modeling performed to determine capacity requirements for U.S. power system operators. This research gap was filled by an analysis of temperature-dependent forced outage rates experienced by the PJM Interconnection, one of the largest regional transmission entities in the U.S., over 25 years.

Carnegie Mellon University researchers determined that extreme hot and cold temperatures suppress output from PJM generators. Capacity requirements were computed for a 12-month scenario that represented current practices in which unconditional independence is assumed, and for a scenario that allowed for generator availability to depend on temperature. The impact of accelerating changes to the resource mix, such as switching from fossil fuels to renewable energy sources, and future temperature increases under climate change may affect resource adequacy at PJM.

After accounting for temperature dependence of generator availability, monthly capacity procurement targets were shown to substantially reduce annual average reserve procurement in PJM with negligible effect on accumulated loss of load expectation, or the probability of a blackout due to insufficient power generation. The mild temperatures experienced during spring and fall months result in lower loads and increased generator availability.

The monthly or seasonal capacity procurement proposed could reduce PJM’s reserve margin from the 26.6% reserve margin posted during 2018 to 2019 to 22.9% and provide a $315 million annual economic benefit.

The research is published in Applied Energy.

Distributions of available capacity as a function of temperature for PJM’s conventional generator fleet (narrow curves, various colors). Note reduced availability at both cold and hot temperatures. Source: Sinnott Murphy et al.