Reading a Fuel Contract:
Beyond the Commodity Price

An on-site power model can look complete while its fuel basis is only a price assumption. The model may multiply expected consumption by an index and call the result fuel cost. It may not show whether the site can receive the required quantity, at the required pressure and quality, on the days and hours when the equipment must run.

A dependable fuel path usually crosses several layers: commodity purchase, interstate or intrastate transportation, local utility delivery, metering, balancing, and the physical connection between the utility meter and the generating equipment. FERC's current Energy Primer describes physical natural-gas contracts as specifying the parties, price, quantity, receipt and delivery points, term, and other conditions, with quality and payment terms also addressed where applicable.⁶ Those clauses are connected. A firm commodity sale does not necessarily create firm transportation, and firm upstream capacity does not necessarily remove a local delivery constraint.

The owner-side task is to translate every layer into one operating statement: what fuel reaches which point, in what usable condition, under what priority, for what cost, and what happens when the planned path does not perform. This paper offers a framework for that translation. It is not contract drafting or legal, tariff, engineering, or commodity-trading advice.

Section 01Begin at the equipment inlet

The fuel requirement should start with the generating system's duty, not a monthly bill. Define the expected operating profile, minimum stable condition, start sequence, ramp, peak and sustained fuel demand, standby behavior, maintenance state, ambient case, and any combined heat requirement. Convert gross equipment consumption to the net service the facility values after compressors, pumps, heaters, treatment, ventilation, and other auxiliaries.

Then state the required inlet boundary: pressure range, temperature, energy content, composition, contaminants, flow variation, startup availability, and allowed rate of change. A source can satisfy an annual volume estimate and still fail this boundary during a start, a coincident peak, or a pressure reduction. The governing demand is the one associated with the operating case the project is meant to solve.

Finally, locate the custody-transfer and responsibility points. Identify where the commodity seller delivers, where a pipeline or utility accepts and redelivers it, where volume and energy are measured, and where the equipment supplier's requirements begin. Ambiguity between those points creates gaps that are invisible in a single delivered-price line.

Section 02Separate volume from usable energy

Fuel may be nominated, transported, metered, settled, and modeled using different quantity conventions. A physical volume is not the same as an energy quantity. Temperature, pressure, compressibility, and measured heating value can affect conversion and billing. The project model should name each unit, base condition, conversion method, meter, sampling period, and party responsible for the calculation.

PG&E's current Gas Rule 2 says heating value varies by time and place based on the sources being drawn, and it explains that billing uses measured volume together with applicable conversion and heating-value factors.¹ The owner does not need to reproduce a utility tariff calculation inside the commercial model. It does need to reconcile the tariff bill, commodity settlement, and equipment heat input to the same energy basis.

Test minimum, expected, and maximum operating cases. Check whether contracted daily quantity, take flexibility, imbalance provisions, and meter capability accommodate starts, stops, seasonal operation, and unplanned load changes. If the equipment consumes less fuel because it is unavailable, the owner may still face reservation, minimum-use, or commodity obligations. If it consumes more, the site may face a different price, an imbalance, or unavailable capacity.

Section 03Pressure is part of the service

A gas connection can exist without providing the pressure an energy system requires. PG&E's current Gas Rule 2 distinguishes standard delivery pressure from higher-than-standard delivery pressure and states that higher pressure is supplied only where available from existing facilities, at the utility's option, with the utility retaining the right to reduce it to no less than standard pressure.¹ That distinction should appear directly in the project evidence.

Ask for the delivery point, normal and allowable pressure range, expected behavior during system peaks, regulator arrangement, metering pressure, notice of changes, and responsibility for special facilities. Compare that evidence with equipment inlet requirements across startup, steady operation, and transients. Do not use a sales statement about “gas availability” as evidence of adequate pressure.

If compression is proposed, treat it as a power-consuming reliability subsystem. Define its electrical source, redundancy, maintenance, controls, ventilation, noise, permitted operating state, and behavior during grid loss. A compressor intended to enable resilient generation may itself depend on the grid unless the startup sequence provides another source. Its parasitic demand also reduces net electrical output and changes economics.

Section 04Quality is an operating variable

Pipeline gas is not a single immutable composition. The contract and tariff boundary may address heating value, moisture, contaminants, interchangeability, and measurement. Equipment limits may be narrower or expressed differently. The owner should map utility specifications to the generating system's fuel specification rather than assuming that acceptance into a pipeline proves fitness at the equipment inlet.

PG&E's Gas Rule 2 says the sources of supplied gas can vary and places responsibility on users whose processes are affected by impurities above specified minimum levels to test and render the gas suitable for their intended uses.¹ PG&E's current renewable-gas rule requires renewable gas to satisfy the base gas-quality specifications and additional constituent requirements, and it provides for quality monitoring and verification at interconnection.⁵ The relevance for an end-use power decision is straightforward: a renewable attribute does not remove the need for an equipment-compatible fuel specification.

Define who samples, how often, at which point, using which method, and what happens after an off-spec result. Address treatment equipment, bypass, alarms, shutdown, rejected deliveries, damage allocation, data access, and return to service. If fuel quality affects output, emissions, maintenance, or warranty conditions, those consequences belong in the same operating model.

Section 05Read firmness across the whole chain

“Firm gas” can refer to several different commitments. The commodity seller may promise supply. The interstate pipeline may reserve transportation capacity. An intrastate system may confirm a nomination. The local utility may provide service under a tariff priority. The facility may still be exposed at a delivery point, during maintenance, or under emergency conditions. Each use of the word firm should name the service, quantity, path, period, exceptions, and remedy.

FERC distinguishes firm transportation, which reserves capacity and carries reservation and usage charges, from lower-priority interruptible transportation that can be displaced when capacity is unavailable.⁶ PG&E's current Gas Rule 14 states that transportation, storage, or supply services may be reduced, interrupted, or allocated for operational or regulatory reasons when supply or capacity is constrained, and it says service choices affect the frequency and duration of restrictions.³

The model should therefore avoid a binary firm-or-interruptible flag. Build an obligation map for commodity, upstream capacity, storage, nominations, local delivery, and site equipment. Record force-majeure and maintenance conditions, priority, notice, replacement options, financial exposure, and whether the alternate route depends on the same constrained infrastructure.

Section 06Make curtailment an operating case

Curtailment is not only a clause for counsel. It is a plant state. The owner needs to know how notice arrives, who monitors it, who has authority to reduce fuel use, which loads or generating units change state, how quickly the site can respond, and how the site verifies compliance. A noncompliance charge is one risk; an unsafe or disorderly shutdown is another.

PG&E's Rule 14 describes receipt-point allocation, delivery restrictions, local curtailment, operational flow orders, emergency flow orders, and related procedures.³ PG&E's current local-curtailment guidance distinguishes local capacity constraints from wider supply shortfalls and directs affected noncore users to manage allowed burn and supplier coordination.⁹ SoCalGas separately describes system, localized, emergency, and planned-maintenance curtailment conditions under its tariff framework.⁷

Create a curtailment sequence before the project receives resilience credit. Decide whether the facility sheds generation, moves to stored fuel, reduces process load, imports more electricity, shuts down safely, or accepts lost service. Confirm environmental and equipment limits for every alternate state. An alternate fuel that cannot be permitted, stored, tested, or started under the relevant conditions is not an operating fallback.

Section 07Match nominations and balancing to operations

Transportation service can require forecasts, nominations, confirmations, scheduling, and imbalance settlement. PG&E's current Gas Rule 21 states that nominations are subject to service agreements and operational constraints, that firm nominations may receive priority over as-available nominations, and that imbalances are handled through the applicable balancing schedule.⁴ A plant with variable dispatch must connect these administrative cycles to its real operating decisions.

Define who forecasts consumption, submits or changes nominations, receives confirmations, reconciles meter data, and responds outside normal staffing hours. Set a control boundary between the plant schedule and the gas schedule. If electricity prices, utility instructions, thermal demand, or an outage can change dispatch, test whether fuel scheduling can follow without creating an imbalance or losing availability.

The contract review should also locate data latency. An invoice can arrive too late to manage a daily exposure. Give operators access to the confirmed quantity, actual burn, remaining allowance, curtailment notice, pressure trend, and exception status needed for the current operating window. Finance, operations, and the fuel agent should reconcile to one version of the quantity.

Section 08Compare every credible path on one basis

Technology neutrality does not mean treating all paths as interchangeable. It means comparing the complete service each path can deliver. A pipeline path includes commodity, transportation, utility delivery, site facilities, and operating administration. Stored fuel includes inventory, logistics, safety, and environmental limits. Electrification includes utility capacity and resilience. Hybrids include all interfaces between their parts.

DOE's CHP financing primer identifies fuel risk as including price, supply, delivery, and quality, and describes the challenge of matching fuel arrangements with longer-lived project obligations.⁸ The same discipline applies even without external financing: compare the time horizon of the equipment decision with the time horizon and reopeners in the energy arrangement.

Section 09Build the price from its components

A useful price model separates commodity, index location, basis or differential, transportation, reservation, utility delivery, balancing, metering, special facilities, treatment or compression, taxes and fees, environmental obligations, and administrative costs. It identifies which components are fixed, variable, indexed, reopened, or passed through. It also shows what is paid when the plant does not run.

FERC's Energy Primer explains that natural-gas demand and prices can change with weather and constraints, and that physical contracts distinguish price, quantity, delivery point, term, and performance terms.⁶ The owner model should align the chosen index and delivery location with the actual fuel path. A liquid trading point is not automatically the price at the site gate.

Stress the operating cases that matter rather than choosing one escalation rate. Examine high commodity cost, constrained transportation, low utilization, unexpected starts, extended outages, maintenance, off-spec fuel, pressure-related compression, and early termination. Treat every modeled price outside a cited current tariff or executed term as illustrative. Keep the economic result separate from the legal interpretation of any clause.

Section 10Use a fuel-readiness decision gate

A proposed energy system should not receive full operating credit until the fuel evidence covers the complete delivery chain. A short owner-side gate can make missing facts visible:

1. Duty and inlet basisThe plant's operating profile, net service, fuel rate, pressure, quality, startup, and auxiliary needs are defined for the relevant conditions.
2. Quantity reconciliationCommodity, transportation, utility billing, metering, and equipment consumption use named units, base conditions, and conversion rules.
3. Rights and responsibilitiesEvery receipt, delivery, custody, meter, treatment, scheduling, and notice boundary has an evidence owner and controlling document.
4. Firmness and failure casePriority, exceptions, maintenance, curtailment, imbalance, replacement supply, shutdown, and restart are translated into plant actions.
5. Comparable economicsAll fixed, variable, indexed, pass-through, and unused-capacity costs are tested against complete alternative paths on the same service basis.

PG&E's Gas Rule 4 is a useful reminder that the tariff structure determines when a separate service agreement may be required.² The project record should therefore include the current tariff, applicable schedule, service agreement, commodity confirmation, transportation rights, utility correspondence, equipment fuel specification, meter basis, and operating procedure. A proposal summary is not a substitute for those documents.

The result may support firm pipeline service, an interruptible strategy with credible shutdown flexibility, stored fuel, electrification, a hybrid, or no project. The sound choice is the one whose physical and commercial interfaces can be shown without hiding a failure state. A fuel contract earns its place in the power plan when its words reconcile to the equipment inlet and the facility can act on every important exception.