Philadelphia-area natural gas capacity: one utility's 2026 filing shows a firm gap on the design day, met in part by delivered supply

By Sam Strong, Vice President of Business Development, Discovery Energy. Technical review by Tara Dugger, Chief Operating Officer. Updated October 2026.

Metro used: the Philadelphia-Camden-Wilmington, PA-NJ-DE-MD metropolitan statistical area, as delineated in OMB Bulletin No. 23-01 (July 21, 2023): Philadelphia, Bucks, Chester, Delaware and Montgomery counties in Pennsylvania; Burlington, Camden, Gloucester and Salem counties in New Jersey; New Castle County in Delaware; and Cecil County in Maryland. Serving utilities are taken from the Discovery Energy crosswalk built from EIA-176 county lists: PECO Energy Company (PECO) and Philadelphia Gas Works (PGW) in Pennsylvania, with UGI Utilities and Columbia Gas of Pennsylvania also listed for Chester County; Public Service Electric and Gas Company (PSE&G), South Jersey Gas Company (South Jersey Gas) and New Jersey Natural Gas in New Jersey; Delmarva Power and Chesapeake Utilities in Delaware; and Chesapeake Utilities and Elkton Gas in Maryland. This page reads the records for PECO, PGW, South Jersey Gas, PSE&G and Delmarva Power, New Jersey Natural Gas's June 2026 filing (a section below, for events, interruptions and contract changes, not its design day), and, for Chester County, the system-wide records of UGI Utilities and Columbia Gas of Pennsylvania (a section below). It does not cover Chesapeake Utilities or Elkton Gas in the metro: those are coverage gaps, and New Jersey Natural Gas's design day forecast was not read, so confidence is Medium. The figures below are system-wide tables that the utilities do not allocate by county; they are the most local figures the record has, and each is labeled by its geography. PGW's figures come from its 2026-2027 gas cost filing (prefiling February 2026, tariff filing March 2026), which includes the Annual Resource Planning Summary Report PGW filed in March 2025; no later PGW resource plan was found.¹¹⁴

Key takeaways

Which parts of the record fall inside the Philadelphia metro?

The table sorts the record by utility, using the Discovery Energy crosswalk of utilities to metro counties and the OMB county list. None of the utility filings allocates its figures to the metro's counties.¹

Utility records by whether they fall inside the Philadelphia metro (OMB delineation). Source: utility filings in the Notes; county crosswalk from EIA-176.¹

System context: the New Jersey figures below are system-wide, and the New Jersey Board of Public Utilities (BPU) statewide findings are not specific to the metro.

What do the UGI Gas and Columbia Gas PA records show for Chester County?

Two more gas utilities are listed for Chester County. UGI Gas's tariff lists Oxford borough and several townships¹², and Columbia Gas PA's tariff page lists Coatesville¹³. Neither record gives figures for Chester County; both below are system-wide, and neither sets the level on this page.

UGI Gas's peak-day schedule for the year ending September 30, 2027 shows total firm capacity of 2,340,671 Dth and total requirements of 2,280,283 Dth for the whole UGI Gas system, which is 45 counties.¹² The difference is about 2.6% of requirements, calculated from UGI figures.¹²

Columbia Gas PA's Table 4 shows total firm design-day demand of 635.5 MDth per day and net firm capacity of 652.3 MDth per day for 2026-27, whole system.¹³ The table's own last line prints a difference of 18.1; subtracting the two printed figures gives 16.8, about 2.6% of demand, calculated from Columbia Gas PA figures, and the table does not explain the gap between the two.¹³

Both records show capacity above requirements for the whole system. They say nothing about the part of each system that serves Chester County, so the page treats them as context. PECO still sets the base level for the metro.

What does Delmarva Power's record show for New Castle County?

Delmarva Power said in its August 2025 gas cost filing with the Delaware Public Service Commission (the Delaware Commission) that it serves approximately 141,000 customers in its New Castle County service territory, which is the whole of its Delaware gas system as the filing describes it.¹⁴ The filing is a gas cost rate case, not a capacity plan, and neither of its figures below is a design day demand.

Delmarva Power said it will begin the 2025-26 gas cost period with 218,484 Mcf per day of peak or design day supply deliverability available to meet firm sales customer requirements, which counts 60,000 Mcf of design day vaporization at its Wilmington liquefied natural gas (LNG) facility.¹⁴ Its Schedule DPC-1 breaks the total into 119,456 Mcf per day of firm transportation, 39,028 of firm storage and 60,000 of LNG.¹⁴ The filing states no design day demand figure, so this page shows no margin for the Delaware system. The LNG share, calculated by code from the filing's figures, is 27.5% of the 218,484 Mcf per day of supply deliverability (illustrative: supply, not demand).

Delmarva Power contracts that expire in 2028 to 2030, as Schedule DPC-1 lists them (whole Delaware gas system); shares calculated by code from the schedule's figures, illustrative.¹⁴

Two further Transco FT contracts, together 59,631 Mcf per day, are marked Evergreen, which the schedule's note says means no date of termination and at Delmarva Power's option.¹⁴ The filing does not say whether the contracts that expire will be renewed or replaced.

The Delaware Commission found in Order No. 11056 (July 2026) that Delmarva Power's proposed gas cost rates and tariff changes are just and reasonable, and the order records that Delmarva Power will continue to take steps to mitigate increases in fixed costs when managing its pipeline capacity and storage portfolio; it is about gas cost rates and makes no finding on design day capacity.¹⁴ An Exeter Associates memorandum to Commission Staff (January 2026) says Exeter reviewed Delmarva Power's 2025-2026 through 2030-2031 Strategic Natural Gas Supply Plan and found that no changes to the proposed rates or its gas procurement practices were appropriate or necessary; the plan is not among the records read for this page.¹⁴ Delmarva Power's tariff lists medium-volume and large-volume interruptible transportation services; the text read gives no interruption sequence.¹⁴

The record shows no shortfall, no margin and no Commission capacity finding for the Delaware system, so it does not change the base level. PECO still sets it.

What does New Jersey Natural Gas's record show for Burlington County?

System context: New Jersey Natural Gas Company (NJNG) said in its June 2026 filing that in recent years there have been several pipeline events that have led to the restriction of firm capacity.¹⁵ It listed a force majeure at Transco's Station 517 in Columbia County, Pennsylvania, starting gas day December 13, 2025 and lasting 12 days, and a Columbia Milford Compressor force majeure of 7 days, with the start date printed as December 30, 2026, which appears to be a typographical error in the filing and is asked in the right-of-reply letter.¹⁵ NJNG's Exhibit JSS-2 lists 16 daily-balancing periods between December 4, 2025 and March 2, 2026 for interruptible customers, 25 customers, reason operational, and NJNG's Exhibit JSS-5 lists extensions of transportation contracts, so contract ends in the window are extended and not left unreplaced.¹⁵

NJNG said it considers ten-year design day projections of firm load to plan for needed capacity, and that its design day forecast and associated supplies through January 2036 are in Workpaper 7, which was filed separately and was not read.¹⁵ The filing gives whole-system figures and does not name Burlington County, which is placed in NJNG's territory by the EIA-176 crosswalk, so NJNG's margin is not established.

The pipeline events could be read as one F3 factor for NJNG's system; one factor does not raise a level, so the record does not change the base level, which PECO still sets. They are a trigger.

How much spare gas capacity does Philadelphia have on the coldest day?

PECO. PECO said its projected design day requirement for 2026-2027 is based on a design day temperature of zero degrees Fahrenheit, a wind speed of 13 miles per hour and no reserve factor.² Its table compares design day demand with projected total assets, in Dth per day, as PECO filed it. PECO's advance filing states its winter design day requirement as "926,731 mcf or 961,020 dth", so the 926,731 Mcf above and the 961,020 Dth in the table are the same design day quantity in two units, in PECO's own words.²

PECO's Table SA-3, design day demand against projected total assets, Dth per day, PECO system, as filed. The 2026-2027 assets include 36,000 Dth per day of hedged gas under executed contracts. Source: PECO 2026 Purchased Gas Cost filing, testimony.¹

PECO described the 2% as "the current firm gap between total assets and design day demand" that the acquisition of firm assets will eliminate, and said that by 2027-2028 it projects a deficit beyond the design day of 1%.¹ PECO's own statements use the word gap and deficit; this page does not restate the sign convention of the table.

PGW. PGW's Form IRP-Gas 1B lists total peak day gas requirements of 589 MMcf for 2026-2027 and 590 MMcf for 2027-2028, and Form 2A lists net peak day gas supply of the same volumes; the forms show no separate reserve margin, so the margin on the coldest day is not established. PGW said its design day load is derived for a day at 0 degrees Fahrenheit and its design hour for a day at -5 degrees Fahrenheit, and that it intends to supply all current firm customers on the coldest day.³

South Jersey Gas. South Jersey Gas defines its design day as a day with an average temperature of 2 degrees Fahrenheit, or 63 heating degree days.⁴

South Jersey Gas's design day forecast, Schedule MCM-6, Dth, whole South Jersey Gas system, as filed (excess is the schedule's "Excess / (Shortfall)" line).⁴

The excess for 2027-28 is 12.2% of that year's design day requirement, calculated from 70,320 and 577,135.⁴

PSE&G. PSE&G's Schedule F gives peak day supply, requirements and surplus for its whole system, based on a 3% Loss of Load Probability.⁵

PSE&G Schedule F, whole PSE&G system, MDth; the last column is calculated by code as supply less requirements, divided by requirements (illustrative).⁵

System context: the BPU's June 2022 order, summarizing a consultant's report for New Jersey firm customers, said there would be a statewide surplus of 274 MDth per day under the winter design day and a shortfall of 153 MDth per day on a 1-in-90 design day. These are statewide findings, from 2022.⁶

What is driving new natural gas demand?

PECO said that its projected growth in design day and overall demand supports its continuing review of how to manage its natural gas supply portfolio.² The filings read name no new large load by customer or service date.

A search of other official records found one planned natural gas-fired generator in the Pennsylvania counties, West Point (PA) in Montgomery County, 2 MW with a planned year of 2026, none in the four New Jersey counties, and no Federal Energy Regulatory Commission pipeline notice naming a Pennsylvania metro county with a pipeline docket number since January 1, 2025.⁹

Are upgrades arriving in time?

For 2026-2027 PECO said it will use 36,000 Dth per day of delivered supply from its Ratable Hedging program against 16,853 Dth per day of required delivered supply, and it will issue a request for proposals for any further delivered resources. For the longer term it said it is evaluating pipeline open seasons and capacity releases and is continuing its LNG investment at West Conshohocken, with the objective of eliminating the peak-day supply gap.² The Commission approved without modification the settlement of PECO's 2026 gas cost proceeding on October 1, 2026, and approved the settlement of PGW's 2026-2027 gas cost proceeding on July 16, 2026; neither order addresses design day or capacity.⁷

South Jersey Gas said its 75,000 Dth Adelphia/Columbia entitlement is listed for 2026-27 and not after, that its primary operational concern is meeting design day requirements without that path, and that asset management agreements and more Columbia supply substantially mitigate the risk.⁴

Who gets gas first in a shortage?

PGW's tariff says customers on its interruptible transportation rate are subject to curtailment or interruption at any time, and that PGW may curtail or interrupt whenever, at its sole discretion, it determines that available capacity in all or a portion of its system is projected to be insufficient. This is the tariff's wording, not a statement that any curtailment is expected.⁸ The tariffs of PECO, South Jersey Gas and PSE&G were not read for this page.

Winter and market context

Context only, as of October 2026. It does not set the outlook level and makes no prediction of outages. Its sources are listed separately under Market and weather sources and are refreshed on the publication date.

NOAA's Climate Prediction Center said on October 15, 2026 that its November 2026 to January 2027 temperature outlook favors above-normal temperatures for, among other areas, the Ohio Valley and mid-Atlantic regions, a discussion that names regions and not counties, and that the probability of at least a strong El Nino continuing through January to March 2027 is 80%.^B1 The U.S. Energy Information Administration (EIA) said on October 6, 2026 that it expects U.S. natural gas inventories to enter the winter heating season 2% above the previous five-year average, and that prolonged periods of cold weather could increase withdrawals beyond its forecast.^A1A2 EIA lists U.S. liquefied natural gas gross exports of 15 billion cubic feet per day in 2025, 18 in 2026 and 19 in 2027.^A1 These are national and regional facts, not statements about the utilities' systems, and none of them is used to set the outlook on this page.

What is the outlook for Philadelphia gas capacity through 2029?

Discovery Energy rates the outlook for Philadelphia-area natural gas capacity through 2029 as Elevated (confidence: Medium): PECO's 2026 filing lists a firm gap between total assets and design day demand that it meets with delivered supply and a hedging program rather than firm assets, with no in-service date or budget for its LNG increase, though the figures are system-wide and several utilities in the metro were not reached. Documented risk factors: none beyond the base level. Three developments would change the assessment: PECO's next Purchased Gas Cost filing (the gap, the delivered supply and hedging volumes) and the status, date and budget of the West Conshohocken LNG vaporization increase; the end of South Jersey Gas's Adelphia/Columbia entitlement after 2026-27 and how it is replaced; PSE&G's next Schedule F and PGW's next resource planning report, which lists two Texas Eastern storage contracts ending April 30, 2030. For the Burlington County part of the metro, NJNG's design day forecast in Workpaper 7, or another pipeline force majeure that restricts its firm capacity, would also be a trigger.

Outlook levels, from least to most concern: Stable, Watch, Elevated, High, Severe. Levels describe the public record of capacity and supply risk; confidence is reported separately. They are qualitative assessments, not forecasts of outages.

What should Philadelphia-area facilities check now?

• Tariffs and charges, through a utility audit. Confirm each account is on the right rate class and tariff, and that riders, demand charges and capacity-related charges are billed correctly. Over 70% of the clients Discovery Energy has audited were billed incorrectly. An audit verifies tariffs and charges and recovers overcharges before winter costs rise.
• Which service. Confirm whether each site takes firm or interruptible service; PGW's tariff says interruptible transportation customers are subject to curtailment or interruption at any time.
• Which utility. Confirm whether the site is served by PECO, PGW, PSE&G, South Jersey Gas, New Jersey Natural Gas, Delmarva Power or another utility, because the records differ by utility.
• Backup plans and fuel. Check that alternate-fuel and curtailment plans are current and feasible, and that fuel inventories and resupply arrangements are in place before December.
• Upcoming proceedings. Track PECO's next Purchased Gas Cost filing and its LNG project, and South Jersey Gas's next BGSS filing.

Frequently asked questions

Related case studies

Discovery Energy publishes gas capacity case studies for other metros, using the same method and outlook scale.

• Pennsylvania UGI Gas territory natural gas capacity case study (outlook: Elevated)
• Northern New Jersey natural gas capacity case study (outlook: Elevated)
• York natural gas capacity case study (outlook: Elevated)
• Pittsburgh natural gas capacity case study (outlook: High)
• New York City and Westchester natural gas capacity case study (outlook: Elevated)

All gas capacity ratings by U.S. metro

Notes

1. PECO Energy Company, 2026 Section 1307(f) Purchased Gas Cost filing, testimony and exhibits (Pennsylvania PUC Docket R-2026-3062148; filed on or about June 1, 2026), PDF 13 (design day requirement), PDF 24 and PDF 25 (Table SA-3 and the testimony on the gap and deficit); Pennsylvania PUC dockets listed in philadelphia_metro_classification.csv; metro counties from metro_counties.csv. Utility statements. [PHL-10, PHL-14, PHL-15, PHL-02, PHL-22, PHL-28, PHL-01] ↩
2. PECO Energy Company, same filing, PDF 22 and PDF 23 (delivered supply, Ratable Hedging program, LNG vaporization, peak-day supply gap), PDF 21 (growth in design day); and PECO's advance filing information, Section 16, PDF 189 (design day basis) and PDF 198 (design day requirement stated as "926,731 mcf or 961,020 dth"). Table SA-3 as filed: the page reproduces its figures and PECO's words and does not restate the table's sign convention. [PHL-11 to PHL-13, PHL-16 to PHL-20, PHL-56] ↩
3. Philadelphia Gas Works, 2026-2027 Gas Cost Rate prefiling (Docket R-2026-3060186; prefiling February 2026), Tab 04, Annual Resource Planning Summary Report filed March 2025, Forms IRP-Gas 1B (PDF 500), 2A (PDF 502), 2C (PDF 504), Sections I and IV (PDF 508 and PDF 517). Volumes in MMcf; PGW's peak day is forecast at a 2 degree temperature (footnote to the forms). The expiration dates in PHL-07 are matched to the storage rows by their order. Utility statements. [PHL-02 to PHL-08] ↩
4. South Jersey Gas Company, 2026-27 BGSS and CIP filing (June 1, 2026), Schedule MCM-6 (PDF 147) and testimony of Maria C. Mendoza (PDF 115 and PDF 213). Utility statements. The 12.2% is run by code (philadelphia_calculations.csv; illustrative): 70,320 divided by 577,135. [PHL-22 to PHL-27] ↩
5. Public Service Electric and Gas Company, 2026 BGSS-RSG filing (May 29, 2026), Item 16 Schedule F Peak Day Gas Requirements and Supply, PDF 94. Utility statements. The surplus percentages are run by code (philadelphia_calculations.csv; illustrative): supply less requirements, divided by requirements. The two later winters in the same schedule (3,225.7 and 3,208.9 MDth of supply against 3,080.6 and 3,078.6 MDth of requirements) calculate to 4.7% and 4.2%; this page shows the first three winters. [PHL-28 to PHL-31] ↩
6. New Jersey Board of Public Utilities, Order, Gas Capacity (June 29, 2022), summarizing the report of London Economics International (public, redacted copy saved). Commission order; statewide. [PHL-32, PHL-33] ↩
7. Pennsylvania Public Utility Commission, Orders at Docket R-2026-3060186 (public meeting July 16, 2026) and Docket R-2026-3062148 (public meeting October 1, 2026). Commission orders. [PHL-09, PHL-21] ↩
8. Philadelphia Gas Works, Gas Services Tariff, Supplement 188 (effective September 2026), Rate Schedule IT, PDF 110 and PDF 157. Utility tariff. [PHL-34, PHL-35] ↩
9. EIA-860M inventory for September 2026 (Planned sheet, operator-reported planned dates), filtered to the Pennsylvania, New Jersey, Delaware and Maryland metro counties by code, and a Federal Register search of FERC notices since January 1, 2025 by county phrase, both computed by code. A notice that spells a place differently would be missed. [PHL-36 to PHL-39] ↩
10. Not established, and left out of the page: supply events since January 1, 2020 affecting the serving systems in an official record (none found in the records read); delivery-point utilization from pipeline postings (not captured; next capture about March 2027); who pays (cost allocation among classes) and the interruption terms for PECO, South Jersey Gas and PSE&G; PECO's service date and budget for the LNG vaporization increase, and whether the Commission has approved it (PECO's Petition for a Finding of Necessity, Docket P-2021-3024328, is referenced in the filing; its outcome was not read); Delaware (Chesapeake Utilities) and Maryland (Chesapeake Utilities and Elkton Gas) records, which scripts could not download, and New Jersey Natural Gas's design day forecast (Workpaper 7, not read); and, for Chester County, any figures specific to the county in the UGI Gas and Columbia Gas PA records (system-wide only).
11. R3 not established beyond the searches in Note 9, and left out of the claims: state air permit records (Pennsylvania Department of Environmental Protection, New Jersey Department of Environmental Protection), the PJM interconnection queue by county, and FERC eLibrary certificate filings, none of which a script could save; news reports are leads only and are not claimed.
12. UGI Utilities, Inc. - Gas Division, 2026 base rate case (Pennsylvania PUC Docket R-2025-3059523), Book II, Attachment SDR-COS-10 page 5 (PDF 22) and Book X, tariff Supplement No. 59, Description of Territory (PDF 11). Utility statements, system-wide. The 2.6% is run by code (philadelphia_calculations.csv; illustrative): capacity less requirements, divided by requirements. [PHL-57 to PHL-59] ↩
13. Columbia Gas of Pennsylvania, Inc., 30-day 1307(f) pre-filing (Docket R-2026-3060762), Exhibit 5, Table 4 (PDF 171), and tariff Supplement No. 221 filed in Volume 5 of its 2024 rate case (Docket R-2024-3046519; PDF 21). Utility statements, system-wide. The 16.8 and 2.6% are run by code (philadelphia_calculations.csv; illustrative) from the printed Net Capacity and Total Demand. [PHL-60 to PHL-63] ↩
14. Delmarva Power & Light Company, Application for approval of its 2025-2026 Gas Cost Rate (Delaware Public Service Commission Docket 25-0832, filed August 28, 2025; public version), direct testimony and Schedules DPC-1 (PDF 64) and DPC-2; Delaware Public Service Commission, Findings, Opinion and Order No. 11056 (July 15, 2026); Exeter Associates memorandum to Staff (January 20, 2026); tariff compliance filing (July 20, 2026). Utility statements, a Commission order and a consultant memorandum; Delmarva Power's figures are for its whole Delaware gas system. The shares in the table are run by code (philadelphia_calculations.csv; illustrative): contract volume divided by 218,484 and by 119,456. The six firm transportation rows add to 119,457; the schedule prints a subtotal of 119,456 (a difference of 1, in the source), and the shares use the printed subtotal. Not established for Delmarva Power: a design day demand figure, the margin, who pays among customer classes, the interruption sequence, supply events since 2020, and the Strategic Natural Gas Supply Plan, which is not in the saved records (manual download). [VA1-DE-01, VA1-DE-02, VA1-DE-03, VA1-DE-04, VA1-DE-05, VA1-DE-06, VA1-DE-07, VA1-DE-08, VA1-DE-09, VA1-DE-10, VA1-DE-11, VA1-DE-12, VA1-DE-13, VA1-DE-14, VA1-DE-15, VA1-DE-16, VA1-DE-17, VA1-DE-18, VA1-DE-19, VA1-DE-20] ↩
15. New Jersey Natural Gas Company, 2027 BGSS and CIP annual filing (petition, testimony of Shah, Micak and Peracchio, exhibits JSS-1 to JSS-5), BPU Docket GR26060281, June 1, 2026, PDF 92 and 93 (planning and pipeline events), PDF 102 and 103 (Exhibits JSS-2 and JSS-3) and PDF 106 (Exhibit JSS-5). Utility statements; manual browser download by Sam Strong, 2026-10-26. The county placement is from the EIA-176 crosswalk, not the filing. [PHL-64 to PHL-75] ↩

Market and weather sources

Public web sources saved and hashed on October 25, 2026. They are context, separate from the regulatory record cited in the Notes. The Climate Prediction Center issues its seasonal outlook once each month near mid-month; this section is refreshed on the publication date.

1. A1. U.S. Energy Information Administration, press release, "EIA expects a mixed picture for winter fuel costs this year," October 6, 2026. Link ↩
2. A2. U.S. Energy Information Administration, Short-Term Energy Outlook, October 2026 (natural gas storage). Link ↩
3. B1. NOAA Climate Prediction Center, Prognostic Discussion for Long-Lead Seasonal Outlooks, issued October 15, 2026. Link ↩

Sources

1. PECO Energy Company, 2026 Section 1307(f) filing, Pennsylvania PUC Docket R-2026-3062148. Link
2. Philadelphia Gas Works, 2026-2027 Gas Cost Rate filing, Pennsylvania PUC Docket R-2026-3060186. Link
3. South Jersey Gas Company, 2026-27 BGSS and CIP filing. Link
4. Public Service Electric and Gas Company, 2026 BGSS-RSG filing. Link
5. New Jersey Board of Public Utilities, Order, Gas Capacity, June 29, 2022. Link
6. Philadelphia Gas Works, Gas Services Tariff. Link
7. Delaware Public Service Commission, Docket 25-0832, Delmarva Power & Light Company 2025-2026 Gas Cost Rate (DelaFile; manual browser downloads logged in the source register).
8. New Jersey Natural Gas Company, 2027 BGSS and CIP annual filing, New Jersey Board of Public Utilities Docket GR26060281, June 1, 2026. Link
9. Office of Management and Budget, OMB Bulletin No. 23-01, Revised Delineations of Metropolitan Statistical Areas, Micropolitan Statistical Areas, and Combined Statistical Areas, July 21, 2023.
10. U.S. Energy Information Administration, EIA-860M Preliminary Monthly Electric Generator Inventory, September 2026. Link
11. Federal Register, API search of Federal Energy Regulatory Commission notices by county. Link