PJM maintained reliability through peak weather conditions amid growing demand and tightening reserve margins.
As 2025 began, PJM’s generation and transmission fleet supported reliable operations and notched new winter demand records during a week-long January freeze.
An Arctic Outbreak that started on Jan. 18 brought single-digit temperatures to much of PJM and neighboring grids.
By Jan. 22, PJM demand swelled to an hourly peak of approximately 143,700 MW between 8 a.m. and 9 a.m. At the same time, PJM kept exporting 8,000 MW to support surrounding grid stability.
That successful performance surpassed PJM’s prior all-time cold season record of 143,400 MW peak set in 2015.
PJM also served its fifth highest and sixth highest winter loads on Jan. 21 and Jan. 23, the last of the six-day event.
PJM’s reliable operations were made possible by improved preparations for wintry weather and notable collaboration between PJM and member companies.
Actions taken included generator testing prior to freezing weather, early commitment of gas-fired units, reliable short-term load forecasting, and temporary return-to-service of vital transmission facilities from maintenance or construction outages.
New Winter Preparedness Measures
PJM entered the winter of 2025/2026 with an operational capacity of 180,804 MW, a slight decline in available resources from the year prior but sufficient to meet reliability standards.
In October 2025, new cold weather readiness standards for generators formulated by the North American Reliability Corp. (NERC) became effective.
NERC oversees reliability for the grid operators in North America on behalf of the Federal Energy Regulatory Commission (FERC).
The new mandatory NERC standards require that generation resources:
-- Implement freeze protection measures and other steps to prepare units for winter [natural gas-fired units in particular].
-- Disclose any operational constraints that impact their operations in freezing weather to dispatching grid authorities [in particular, natural gas-fired units] and submit corrective action plans for such constraints. This information enhances PJM’s existing database of minimum operating temperatures for each of the resources in its generation fleet.
Beyond new mandatory standards, PJM has long required generators to follow a specific mandatory cold weather checklist and is constantly improving winter preparedness.
Steps like these enhance collaboration with, and readiness of, critically needed generation during extreme cold--
-- For the winter of 2025/2026, PJM planned to double the number of winter preparedness site visits to 30 generator facilities in tandem with staff from ReliabilityFirst.
-- PJM urged generators to self-schedule for testing, particularly when temperatures are forecast to fall below 35 degrees. Leading up to and throughout winter, PJM also conducts unannounced Operational Tests of dispatchable generation units.
-- PJM enhanced the Cold Weather Operating Limit Data Request to better align with NERC Standards for determination of a unit’s minimum operating temperature and startup temperature from a cold state of operation.
-- During critical periods, PJM units will regularly update their dynamic [natural] gas supply availability via a new Markets Gateway data field.
-- PJM continued weekly, and daily as necessary, communication and coordination with [natural] gas pipeline operators to improve situational awareness of possible supply limitations.
Milestone Summer Performance
When temperatures arrived at the other end of the thermometer in summer, PJM kept air conditioners and fans going for the 67 million people in its footprint.
The early summer heat wave, June 22–June 26, gave rise to PJM’s third- and fourth-highest all-time summer peaks, approximately 162,400 MW and 161,800 MW, respectively, on June 23 and June 24. June 29 peak load of approximately 157,500 was the ninth highest.
While using all generation available, PJM tempered late afternoon electricity demand by calling on customers who receive compensation in exchange for trimming power use.
Customers like these, enrolled in what is known as load management or demand response programs, participated to ease load during critical periods.
In all, PJM initiated six load management events last summer.
Major Substation Failure Prompts Coordinated Response To Avert Widespread Outages
PJM Operations’ response to a predawn critical substation outage on Aug. 11 mitigated the risk of up to 1,200 MW load loss around Baltimore.
As equipment failures multiplied in the dawn hours before the morning peak, PJM implemented emergency procedures in the BGE transmission zone and returned to service some generating units from maintenance outages.
Daylong relief measures included a call on all Demand Response resources in the BGE zone. As studies showed risk of widespread urban outages near the afternoon peak,
PJM initiated a Load Shed Directive to interrupt approximately 20 MW of system load for 28 minutes.
Solar Additions Highlight Changing Resource Mix
Contributions by solar resources serving PJM energy needs reached an all-time PJM high on April 18 of nearly 12,000 MW.
This growth in solar output coincided with continuing solar growth in the PJM fleet. In 2025, 2.2 GW of solar generation was added, while PJM also netted 55 MW of new wind and 29 MW of new coal resources.
Preparedness for Peak Conditions and Load Growth
PJM coordination with member generation and transmission owners was enhanced in multiple ways during 2025. Actions included--
-- Expanded Demand Response Availability: PJM expanded its demand response (DR) availability window from limited windows (10 a.m. to 10 p.m. in summer, 6 a.m. to 9 p.m. in winter) to availability 24 hours daily. This change improves grid reliability by including DR resources during all hours of risk and takes effect for the 2027/2028 Delivery Year.
-- Expanded Transmission Outage Studies: PJM broadened study and coordination of the operational impacts of transmission outage events long beyond prior analyses, which looked six months ahead. A new joint PJM planning and operations project now models substations and facilities up to two years in the future to identify and mitigate conflicts caused by major transmission construction required by growing demand and generator retirements, particularly in the AEP, BGE, PEPCO, FE South and Dominion transmission zones.
-- Inverter-Based Resource Alert: In May, PJM issued an alert to communicate critical readiness actions to be taken by inverter-based resources. Steps included required unit adherence to NERC reliability standards for voltage stability and ride-through settings. In addition, PJM Manuals outline steps required for a Wind and Solar Unit Dispatchability Checklist and the need to accurately report and update reactive capability and provide active voltage regulation.
-- Wildfire Procedure: PJM stakeholders endorsed a Manual 13 revision to create the first PJM Wildfire Procedure. This codifies coordination and preventative measures PJM undertakes with Transmission Owners prior to and during wildfire events.
U.S. Department of Energy 202(c) Orders
PJM supported U.S. Department of Energy orders in 2025 to defer retirements of select dispatchable generation units in light of growing resource adequacy concerns.
Beginning last spring, DOE directed the continued operation of Constellation’s Eddystone Generating Station units 3 and 4, both 380 MW steam plants in Pennsylvania, past their previously planned retirement dates.
In July, a DOE order approved a PJM request and directed Talen-owned Wagner Unit 4 in Maryland to run beyond emissions limits during reliability emergencies to help maintain voltage stability and prevent thermal overloads.
PJM collaborated with stakeholders to arrive at unit compensation guidelines to support continued operations of these facilities, rules that were approved by FERC late in 2025.
Throughout the year, PJM continued efforts to assist stakeholders, states and unit developers in overcoming hurdles beyond its control to bringing dispatchable generation online.
Storage as a Transmission Asset
PJM picked up stakeholder work on how to integrate storage facilities as transmission assets into PJM operations. This work continues in the stakeholder process and is expected to enhance needed flexibility for PJM dispatch.
GridEx VIII
PJM practiced systemwide crisis response at the semiannual GridEx drill event Nov. 18–20. The exercise drew industrywide participation and, for the time, direct participation or observation by representatives from six states.
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Visit the PJM Interconnection website for more information.
Resource Links:
-- PA Energy, Environmental, Citizen Advocates Call On PUC To Protect Ratepayers, Communities From Costs, Impacts Of A.I. Data Centers [PaEN]
Resource Links - Energy Affordability:
-- PUC: Most PA Electric Utility Consumers To See 3.7% To 10.6% Increase In Electricity Prices During The Next 3 Months Starting Dec. 1 [PaEN]
-- Morning Call - Elizabeth Deornellas: How A.I. Data Centers Are Driving Up The Cost Of Electricity And What Grid Operators Can Do [PDF of Article]
-- Scranton Times - Chris Kelly Opinion: PPL Proposed 7% Rate Hike A.I. Data Center Driven [PDF of Article]
-- PJM Electricity Auction Prices Again At Cap Imposed By Gov. Shapiro’s Lawsuit Settlement, Without It Prices Would Be 59% Higher Driven By A.I. Data Center Demand; Grid Reliability Now Questioned [PaEN]
-- PA Capital-Star: Energy Market Watchers See Electric Bills In PA, Other States Rising As A.I. Data Center Demand Continues
-- PaGasSwitch.com: Natural Gas Costs Increased From 9.26% to 57.5% Over The Last Year For Natural Gas Utility Customers Not Shopping For A Fuel Supplier [PaEN]
-- Post-Gazette - Anya Litvak: PUC Approves Columbia Gas Rate Increase - 13th Since 2008
-- PUC Highlights Ways Natural Gas Customers Can Manage Winter Energy Use, Costs, Explore Energy Affordability Options [PaEN]
-- PUC Publishes Updates To Low-Income Natural Gas, Electric Utility Usage Reduction Program Regulations [PaEN]
-- PUC Chairman Highlights 'Extraordinary Challenges' Pennsylvania Families Are Facing This Winter With Energy Bills And His Appreciation For Groups Providing Assistance [PaEN]
-- Post-Gazette - Anya Litvak: What’s Important In Affordable Energy? A Conversation With A Carnegie Mellon Energy Justice Professor
-- Data Center Stampede Trampling PA Ratepayers Part I: PA Utility Law Project - Utility Terminations Up 30% Already; Prioritize Existing Loads; Centers Need To Help Pay For Utility Assistance [PaEN]
-- Data Center Stampede Trampling PA Ratepayers Part II: PA Consumer Advocate - PUC Should Set Conditions For Centers To Be Served By The Grid; Set Power Curtailment Priorities [PaEN]
-- Data Center Stampede Trampling PA Ratepayers Part III: PJM Market Monitor - Data Centers Have Cost Existing Ratepayers $16.6 Billion Already; Centers Should Bring Their Own Power Generation To Prevent More Large Price Spikes [PaEN]
-- PJM Electric Auction Impacts: 1 In 5 PA Households Report Problems Now Paying Energy Bills; Electric Utility Shutoffs Up 38.1% So Far This Year [PaEN]
-- PJM Electricity Auction: PJM Lost 2.8 Gigawatts Of Power Due To Reduced Reliability Rating Of Natural Gas Power Plants; Could Gain 12.2 Gigawatts By Increasing Reliability From Less Than 75% Now To An Achievable 90% [PaEN]
Resource Links - Who Pays:
-- PUC Invites Comments On Proposed Model Tariff To Balance A.I. Data Center Growth And Ratepayer Protection [PaEN]
-- PUC Votes To Develop Rulemaking To Modernize Electric Interconnection Regulations; Proposed Rule Due In March [PaEN]
-- PUC Commissioners Agree On Need To ‘Get It Right’ On Reforming Grid Connection Process For Solar, Renewable, All Energy Sources To Protect Consumers, Grid Reliability [PaEN]
-- Post-Gazette - Anya Litvak: PUC Proposes Special Treatment For A.I. Data Center Power Connections To Contain The Cost Burden On Existing Ratepayers [PDF of Article]
-- Federal Energy Regulatory Commission Orders PJM To Allow A.I. Data Centers To Connect Directly To Power Plants, Expedite Connections For Shovel-Ready Projects, Enhance Load Forecasting [PaEN]
-- WESA - Rachel McDevitt: PJM Grid Operator Covering PA Failing To Plan For Responsible A.I. Data Center Load Growth, Observers Say
-- PJM Market Monitor Files Complaint With FERC Saying PJM Is Proposing To Allow A.I. Data Centers To Connect To Grid That It Cannot Reliably Serve, Will Require Blackouts To Maintain Service [PaEN]
-- On The Eve Of New PJM Capacity Auction: Gov. Shapiro, 5 Other Governors Say PJM's Efforts To Deal With A.I. Data Center Demands Have Failed; Urge 'Decisive Action' To Avoid 'Extraordinarily’ High Prices [PaEN]
-- The Center Square: Consensus For Soaring A.I. Data Center Power Demands Still Elusive Among PJM Members
-- PA Capital-Star: PJM Grid Operator Weighs Proposals To Manage A.I. Data Center Impact On Electricity Affordability And Reliability
-- WITF/LancasterOnline: Mild Forecast For PA Winter Heating Bills In Peril As Natural Gas Prices Surge
-- PUC Directs Staff To Develop Rule On Winter Terminations, Payment Arrangements, Other Consumer Protections
Resource Links - Grid Reliability:
-- North American Electric Reliability Corp: Electric Grid At Elevated Risk Of Insufficient Energy Supplies During Extreme Weather Due To Rising A.I. Data Center Demands, 'Precarious' Natural Gas Supplies [PaEN]
-- Utility Dive: North American Electric Reliability Corp: Winter Peak Demand Is Rising Faster Than Resource Additions
-- Reuters: US A.I. Data Center Demand Raising Power Risks This Winter, NERC Says
-- Bloomberg: US Faces Winter Blackout Risks From A.I. Data Centers’ Power Needs, NERC Says
-- WGEM: Illinois State Regulators Warn Of Impending Energy Shortfalls As PJM Capacity Prices Rise Again
-- KSDK: A.I. Data Centers Are Sucking Illinois’ Power Grid Dry, Official Report Warns [PJM Service Area]
Related Articles This Week:
-- PA House Committee Approves Legislation Giving Local Officials Greater Say Over Regional-Scale Developments Like A.I. Data Centers, Warehouses [PaEN]
-- Sen. Boscola, Sen. Vogel Introduce Bipartisan Legislation To Promote Development Of Much-Needed Solar Energy Electric Generation Facilities And Lower Costs For Consumers [PaEN]
-- DEP: Seneca Resources Still Experiencing Spills, Releases While New Well Development Continues At Taft Shale Gas Well Pad In Middlebury Twp., Tioga County For 426 Days And Counting [PaEN]
-- Environmental Hearing Board Denies DEP Motion To Dismiss BCD Properties Appeal Over Its Illegal Disposal Of Oil And Gas Wastewater By Road Dumping; Case To Proceed On Its Merits [PaEN]
-- Spotlight PA: Map Shows Growing Number Of A.I. Data Centers Planned Across Pennsylvania
NewsClips:
-- Altoona Mirror: PA House Moves Legislation Giving Local Governments Authority Over Projects Of Regional Significance [House Bill 1764]
-- WHYY - Susan Phillips: New Financing Available For Philly-Area Homeowners Seeking To Install Rooftop Solar Energy Generation
-- Warren Times: Don’t Count On Lower Electricity Prices In 2026 [Data Centers Driving Increases]
-- PennLive Letter: President’s War On Wind Energy Will Make Your Electric Bill Higher - By David Kyle, New Columbia
-- Wall Street Journal: Be Prepared To Keep Paying More For Electricity - A.I. Data Center Demands, Rising Natural Gas Prices, Grid Infrastructure Costs [PDF of Article]
-- Reuters Commentary: Five Energy Market Trends To Track In 2026 - The Year Of The Oil, LNG Natural Gas Glut
-- PennLive Guest Essay: The Public’s A.I. Power Problem Is Not Electricity, It’s The Failure To Protect Ratepayers From Costs They Did Not Choose- Matt Hasan, Ph.D, CEO of aiRESULTS
-- TribLive: What To Look For In 2026 In Western PA [Data Centers, 4.5 GW Homer City Power Plant]
-- Scranton Times: A.I. Data Center Proposed In Ransom Twp., Lackawanna County [86th Data Center Building In The County] [PDF of Article]
-- Scranton Times: Abandoned Mine Subsidence Sinkhole That Swallowed Car Filled, Patched In Blakely, Lackawanna County
-- Reuters Commentary: The 2025 Energy Transition In 8 Charts - Clean Wins, Dirty Setbacks
[Posted: January 1, 2026] PA Environment Digest
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