Capital Program Planning for South Carolina Gas Utilities

by | Oct 21, 2026

South Carolina · Natural Gas Utilities

South Carolina is adding gas customers faster than almost any state. Your capital plan has to keep pace.

A booming population is stacking new services onto a distribution system that already runs to roughly 19,500 miles of main, while gas-cost swings, the Rate Stabilization Act clock, and long-horizon decarbonization risk all pull at the same budget. Each of those forces reshuffles the projects on your list. Invizion helps gas utilities re-sequence a capital portfolio in a click — and defend every decision.

See how Invizion helps utilities See what South Carolina utilities face Download the briefing (PDF)
The bottom line: South Carolina is adding gas customers faster than almost any state, but the same budget has to modernize ~19,500 miles of aging main, absorb volatile gas costs, and hedge decades-long decarbonization risk — all on the Rate Stabilization Act's annual clock. The utilities that stay ahead will be the ones whose capital plans can re-sequence as fast as the pressures change.
+17.2%1
Growth in South Carolina residential natural gas customers, 2019–2024 — from 714,218 to 837,026.
~19,500 mi2
Distribution mains Dominion Energy South Carolina must inspect, maintain, and replace on a rolling basis.
Net zero by 20502
Dominion Energy's carbon and methane emissions target — the long-horizon backdrop to every 30-year pipe investment.
$16.913
Average South Carolina residential price per thousand cubic feet in 2024 — the affordability line every rate filing meets.

The South Carolina Landscape

Four forces are moving your project list at once

None of these is theoretical, and none of them waits for your next budget cycle. Together they mean the capital plan you approved last year may already be the wrong plan.

Integrity — Aging Pipe & Safety

Thousands of miles of main, all on a replacement clock

Dominion Energy South Carolina alone operates roughly 19,500 miles of distribution main and about 400 miles of transmission pipeline, with peak-shaving LNG at Charleston and Salley.2 Every operator in the state — investor-owned and municipal alike — must run a federal distribution integrity management program that identifies and mitigates risk across that mileage.4

Older bare and coated steel has to be found, prioritized, and replaced before it becomes a leak or an incident. That is a decades-long capital commitment competing every year with growth-driven expansion.

Decarbonization — Long-Horizon Risk

30-year assets against a net-zero backdrop

South Carolina has no gas ban or building-electrification mandate, but the pressure is real on a longer clock. Dominion Energy has committed to net zero carbon and methane emissions by 2050, and its own filings warn that greenhouse-gas rules and efficiency trends “could affect demand for natural gas.”2

Main that is installed today is recovered from ratepayers over 30 to 50 years. When throughput and the long-term customer count are uncertain, the sequencing of that spend — not just its size — is where stranded-asset risk is managed.

Supply — Price & Reliability

Winter peaks and a volatile commodity

South Carolina has no gas production of its own; supply arrives on the Transcontinental (Transco), Southern Natural Gas, and Dominion Energy Carolina Gas Transmission pipelines, with LNG held for peak days.2 Power generation is by far the largest gas user in the state — about 176 billion cubic feet in 2024, against 33 Bcf residential — so winter heating load competes with the grid for the same molecules.5

Commodity swings pass through to customers via a monthly purchased gas adjustment, which is why the 2024 residential price still sat near $16.91 per Mcf after recent cold-snap spikes.32

Capital — Recovery & Growth

The fastest growth in the Southeast, on an annual rate clock

South Carolina's population grew 8.8% between 2020 and 2025, one of the highest rates in the nation,8 and residential gas customers rose 17.2% over five years.1 Every new subdivision is main, services, and meters that have to be funded now and recovered later.

The Natural Gas Rate Stabilization Act lets utilities reset base rates annually rather than wait years between cases — but the earnings band is tight and the calendar is fixed, so the capital that gets recovered is the capital that can be justified when the filing is due.6

Who Delivers South Carolina's Gas

Two large regulated LDCs and a deep bench of municipal systems

South Carolina's gas is delivered by two investor-owned distribution companies regulated by the Public Service Commission, alongside a large number of city- and authority-owned municipal systems. The pressures are shared; the accountability path differs.

Investor-owned LDCs

Rates & capital recovery regulated by the PSC

Dominion Energy South Carolina (DESC) ~500,000 gas customers · formerly SCE&G/SCANA2
Piedmont Natural Gas A Duke Energy company · serves portions of South Carolina910

The regulated market is concentrated: DESC and Piedmont together serve the large majority of South Carolina's roughly 837,000 residential gas customers.12

Municipal & public gas systems

Governed by councils & boards, not PSC rates

Greer Commission of Public Works Municipal gas, electric & water · Greer11
Fort Hill Natural Gas Authority Public gas authority · York County region
Patriots Energy Group Gas-supply joint-action agency for SC municipal systems
Additional city systems Orangeburg DPU and other municipal gas providers statewide12

The Office of Regulatory Staff runs gas pipeline safety oversight across the state's operators, and public gas systems nationwide — more than 730 in 38 states — face the same integrity obligations as the investor-owned LDCs.1214

Rate-Setting & Oversight

Every capital dollar has to be defensible

Whether you file with the Public Service Commission or answer to a city council, the question is the same: why this project, why now, why at this cost?

  • South Carolina Public Service Commission (PSC) regulates the rates and service of the investor-owned gas distributors, DESC and Piedmont Natural Gas.13
  • Office of Regulatory Staff (ORS) represents the public interest in rate proceedings and runs the state's natural gas pipeline safety program.12
  • Natural Gas Rate Stabilization Act (S.C. Code §§58-5-400 to 58-5-480, effective 2005) lets gas LDCs reset base rates annually within a return-on-equity band of ±50 basis points — monitoring reports in March, an initial order by October 15, and new rates effective November 1.62
  • Purchased Gas Adjustment & Weather Normalization — DESC recovers prudently incurred gas commodity and transportation costs through a monthly PGA and normalizes winter bills through a weather adjustment.2
  • Piedmont's South Carolina rate stabilization adjustment resets rates annually on updated costs and revenues; unlike its North Carolina and Tennessee territories, Piedmont does not run a separate integrity-management rider in South Carolina.7

Funding On The Table

Where the capital comes from

Gas utilities fund modernization through a mix of surcharge-based recovery and, increasingly, federal safety grants. The constraint is readiness: which projects qualify, which are shovel-ready, and how the timing lines up with the rate calendar.

  • PHMSA NGDISM grants — $200M/year, $1B over five years. The federal Natural Gas Distribution Infrastructure Safety and Modernization program funds repair and replacement of leak-prone pipe; municipal gas systems are eligible applicants.15
  • Rate Stabilization Act recovery is the workhorse: annual base-rate resets keep integrity and growth capital moving without the multi-year lag of a full rate case, provided earnings stay inside the ±50-basis-point band.6
  • Monthly Purchased Gas Adjustment passes commodity and pipeline transportation costs straight through, insulating base rates from cold-snap price spikes but keeping bills — near $16.91 per Mcf residential in 2024 — exposed to the market.32
  • Customer-growth contributions and system expansion — with residential connections up 17.2% in five years, main and service extensions to new subdivisions are a large and recurring call on capital.1

Where Invizion Fits

Turn South Carolina's gas-system decisions into a defensible capital plan

Invizion is scenario-based capital portfolio optimization built for utilities. When a replacement mandate accelerates, throughput forecasts shift, or a decarbonization ruling lands, you don't re-plan by hand for weeks — you model it and decide with a record to stand behind.

1

Model the “what-if” before it's forced on you

A faster main-replacement schedule, a gas-line-extension ban, an RNG mandate — build the scenario and see the impact on the whole portfolio, side by side with today's plan.

2

Re-sequence 500 projects in a click

When priorities move, Invizion re-orders the portfolio automatically — accelerating, stretching, or deferring projects against the constraints you set, not weeks of spreadsheet surgery.

3

Give regulators or your board a defensible record

Every prioritization and trade-off is captured. When you're asked “why this project, why now,” the answer is documented — not reconstructed after the fact.

South Carolina Gas, In Brief

Questions South Carolina gas leaders are asking

Short, sourced answers — the same facts we dig into with utilities looking at their capital programs.

Who provides natural gas in South Carolina?
Two investor-owned distributors regulated by the PSC — Dominion Energy South Carolina (formerly SCE&G, ~500,000 gas customers) and Piedmont Natural Gas (a Duke Energy company) — plus a large number of municipal and public systems such as Greer CPW and Fort Hill Natural Gas Authority. Statewide there are roughly 837,000 residential gas customers.21
What is the Natural Gas Rate Stabilization Act?
It is a South Carolina statute (S.C. Code §§58-5-400 to 58-5-480, effective 2005) that lets gas LDCs adjust base rates annually within a ±50-basis-point return-on-equity band, rather than waiting years between full rate cases. Monitoring reports are filed in March, an initial order issues by October 15, and new rates take effect November 1.62
How fast is South Carolina's gas customer base growing?
Residential natural gas customers rose from 714,218 in 2019 to 837,026 in 2024, up 17.2%, tracking a population that grew 8.8% between 2020 and 2025 — among the fastest growth in the country.18
Where does South Carolina's natural gas come from?
The state produces none of its own gas. Supply arrives on the Transco, Southern Natural Gas, and Dominion Energy Carolina Gas Transmission pipelines, with LNG at Charleston and Salley held for peak days. Power generation is the largest single use — about 176 billion cubic feet in 2024.25
Is South Carolina trying to phase out natural gas?
No — the state has no gas ban or building-electrification mandate. But Dominion Energy has a net-zero carbon and methane target for 2050, and federal greenhouse-gas rules could dampen long-term gas demand, so utilities weigh throughput and stranded-asset risk when sequencing pipe investments recovered over decades.2
How does Invizion help South Carolina gas utilities plan capital?
Invizion is scenario-based capital portfolio optimization for utilities. It lets you model how a growth surge, a gas-cost spike, a PHMSA grant, or a shifting decarbonization outlook reshuffles your whole project list, re-sequence the portfolio automatically against your constraints and the Rate Stabilization Act calendar, and keep a defensible record of every decision for the Public Service Commission or your board.

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About the Author

GB

Guy Barlow

President, Invizion

Guy Barlow leads Invizion, a capital lifecycle management platform for water and wastewater utilities. He has spent two decades at the intersection of utility capital programs, funding, and analytics, helping utilities make faster, more defensible capital decisions.

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Invizion helps utilities model, optimize, and defend their capital programs. Explore how it works, or read our latest thinking on capital planning across the utility sector.

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This briefing was last reviewed September 2026.

Sources

  1. U.S. Energy Information Administration — South Carolina number of natural gas residential consumers, 714,218 (2019) to 837,026 (2024). www.eia.gov
  2. Dominion Energy South Carolina, Inc. Form 10-K (FY2024, filed Feb 2025) — ~0.5M gas customers, ~19,500 mi distribution main, ~400 mi transmission, LNG at Charleston and Salley, Transco/Southern Natural Gas/Dominion Energy Carolina Gas Transmission supply, Rate Stabilization Act, monthly PGA, weather normalization, SCE&G/SCANA history (Dominion acquisition Jan 1, 2019), net-zero carbon and methane by 2050. www.sec.gov
  3. U.S. Energy Information Administration — South Carolina natural gas residential price, $17.46/Mcf (2023), $16.91/Mcf (2024). www.eia.gov
  4. PHMSA — Gas distribution annual data and distribution integrity management program (DIMP) requirements under 49 CFR Part 192. www.phmsa.dot.gov
  5. U.S. Energy Information Administration — South Carolina natural gas deliveries by sector, 2024: electric power 176,210 MMcf, industrial 95,257, residential 33,367, commercial 26,402. www.eia.gov
  6. South Carolina Code of Laws — Natural Gas Rate Stabilization Act, §§58-5-400 to 58-5-480 (annual rate adjustment, ±50-basis-point ROE band, October 15 initial order, November 1 rates). www.scstatehouse.gov
  7. Piedmont Natural Gas Company Form 10-K (FY2016) — South Carolina Rate Stabilization Adjustment (annual reset), integrity-management rider in NC/TN only, ~1.03 million total customers and ~22,800 mi of distribution main across NC/SC/TN. www.sec.gov
  8. U.S. Census Bureau QuickFacts — South Carolina population 5,118,425 (2020 Census) to 5,570,274 (2025 estimate), +8.8%. www.census.gov
  9. Duke Energy Corporation Form 10-K (FY2025, filed Feb 2026) — Piedmont Natural Gas a wholly owned Duke Energy subsidiary serving portions of North Carolina, South Carolina and Tennessee. www.sec.gov
  10. Piedmont Natural Gas / company profile — over one million customers across NC/SC/TN; wholly owned by Duke Energy since October 3, 2016. en.wikipedia.org
  11. Greer Commission of Public Works — municipal utility providing natural gas, electric and water service in Greer, South Carolina. www.greercpw.com
  12. South Carolina Office of Regulatory Staff — represents the public interest in utility regulation and operates the state's natural gas pipeline safety oversight program. ors.sc.gov
  13. South Carolina Public Service Commission — regulates just and reasonable rates and service of the state's public utilities, including natural gas. psc.sc.gov
  14. American Public Gas Association — more than 730 public (municipal) natural gas members across 38 states. www.apga.org
  15. PHMSA — Natural Gas Distribution Infrastructure Safety and Modernization (NGDISM) grant program, $200 million per year and $1 billion over five years under the Bipartisan Infrastructure Law. www.phmsa.dot.gov