PJM Capacity and Reliability under Rising Large-Load Pressure

PJM Interconnection spans a wide swathe of the Mid-Atlantic and Midwest, including load centres that have become magnets for data-centre development. Capacity market design, interconnection timing and transmission constraints therefore sit at the centre of United States reliability politics. This article sets out the engineering logic that any PJM watcher must hold when large loads arrive faster than firm supply. Annual energy from wind and solar can rise while winter peak adequacy deteriorates if accredited capacity falls with retirements.

EIA's February 2024 inventory showed national planned retirements of 5.2 gigawatts for 2024, with coal and gas dominating exits, after heavier coal retirements in prior years. FERC's Order No. 2023 reforms target the national disease of speculative queues and multi-year waits. Order No. 1920 requires long-term regional planning scenarios and ex ante cost allocation methods. Co-location of large loads with existing generation raises questions about transmission cost allocation and capacity obligations. Fuel assurance for gas units that still set many peak hours remains essential.

Utility and state boards in the PJM footprint should demand aligned timelines for large-load energisation and network upgrades, clear cost causation, updated effective load-carrying capability awareness in public communications, and honest discussion of how much balancing gas and retained nuclear will provide through the late 2020s.