A standby generator runs on natural gas or propane, and the right fuel depends on the house, not on what the installer stocks. Natural gas means no tank to refill and no runtime limit — if the existing line has the capacity to feed the unit, which has to be verified. Propane works where there's no gas line and stores energy densely, but tank size sets your runtime. For a Terrebonne Parish home that loses power for days, both can work; the deciding factors are whether you have a gas line and how long your outages run.
The core trade-off
The choice comes down to a simple trade-off: natural gas gives you a fuel supply you never refill, but it depends on the utility line having enough capacity; propane frees you from the gas utility entirely, but you're limited by what the tank holds. Neither is universally "better" — the right answer is whichever fits your house, your gas service, and your outage pattern. An installer who quotes one fuel without asking about your gas line is defaulting, not deciding.
Natural gas
Natural gas is delivered by the utility line, so there's no tank to refill and no runtime limit from fuel storage — the generator can run continuously as long as the gas keeps flowing. That's the convenience case, especially for long outages where you don't want to think about fuel. The catch is capacity: the existing line must supply enough pressure and volume to feed the generator under full load, which a proper install verifies before promising natural gas.
Propane
Propane stores energy densely in a tank and works anywhere, including homes with no natural-gas line. It keeps well for long periods, which suits a household that loses power rarely but for days at a time — the propane is there waiting whenever a storm hits. The trade-off is runtime: the tank holds a finite amount, so the tank size is matched to the outage length you want to cover. Size it for a realistic hurricane-season outage, not a single day, and it carries you through.
The gas-line check that has to happen first
If you're leaning natural gas, the gas-line capacity check is the step that can't be skipped. A line sized years ago for a stove and a water heater may not deliver enough for a whole-home generator running under full load. Verifying the capacity — and upsizing the line if it falls short — is part of a proper natural-gas install. A quote that promises natural gas without mentioning the line check is either assuming capacity it hasn't confirmed or planning a change order. We cover where that fits in the price in what drives standby generator cost.
How to choose
Start with one question: do you have a natural-gas line with enough capacity? If yes, natural gas is the convenient, no-refueling choice. If there's no line, or the line can't be upsized economically, propane is the answer, with the tank sized to your outages. Either fuel pairs with whole-home or essential-circuit coverage — the fuel and the size are separate decisions we make together.
| Factor | Natural gas | Propane |
|---|---|---|
| Refueling | None — fed by the utility line | Tank refilled as needed |
| Runtime | No limit while gas flows | Limited by tank size |
| Requirement | Gas line with verified capacity | Space for a tank |
| Best for | Homes with adequate gas service | Homes with no gas line; long storage |
Tell us whether you have a gas line and how long your outages run, and we'll tell you which fuel fits — and if it's natural gas, we verify the line capacity before promising it. Related: whole-home install and what size standby generator do I need.