Two fuels, one goal: keeping the lights on
A permanently installed standby generator sits outside your house like an air conditioner condenser and starts on its own when utility power drops. The single biggest decision before installation is what it burns. On the First Coast that almost always comes down to natural gas piped in from the street, or propane stored in a tank on your property. Both run the same style of air-cooled or liquid-cooled unit. The difference is where the fuel comes from, how long it lasts, and whether a supply line even reaches your address.
This guide walks through how each fuel works, the trade-offs specific to Northeast Florida, and the questions worth asking before anyone quotes you. If you would rather skip straight to talking with a licensed local installer, you can request a quote from the vetted contractor we work with.
How natural gas fuels the unit
Natural gas generators tap into the same line that feeds a gas range, water heater, or pool heater. Once the meter and piping are sized correctly, the generator draws fuel on demand. There is no tank to bury, no delivery to schedule, and no refill to worry about during a long outage. As long as the utility keeps gas flowing, and it usually does even when the electric grid is down, the generator can run for days or weeks straight.
The catch is availability. Natural gas only works if a main actually reaches your street. Around here that depends heavily on which side of a county line you sit on. JEA is the municipal utility for Jacksonville and much of Duval County and provides both electricity and natural gas, so many established Duval neighborhoods have gas service already at the meter. In Fernandina Beach and parts of Nassau County, Florida Public Utilities distributes natural gas. Several newer St. Johns County communities are served by TECO Peoples Gas, which is why a growing number of homes in and around Nocatee can go the natural gas route without a tank.
Even with a main nearby, your existing gas meter and line may not deliver enough volume for a generator on top of the appliances you already run. Undersized piping is one of the most common surprises during a site visit, so a good installer measures load before promising anything.
How propane fuels the unit
Propane, sometimes called LP gas, is stored as a liquid in a tank on your property and vaporizes to feed the generator. Its great advantage is that it works absolutely anywhere. No street main required. That makes it the default for rural stretches of Clay and Nassau counties, for wooded acreage, and for outer subdivisions where gas lines never got run. If you already heat with propane or cook on it, adding a generator to the same tank is often straightforward.
Tanks come in above-ground and below-ground versions. Above-ground tanks cost less to set and are easier to service, though some homeowners dislike the look. Buried tanks disappear into the yard but add excavation and cost. Sizing matters more with propane than with natural gas because you are carrying your entire outage on what is in the tank. Many First Coast homeowners choose a 500 or 1000 gallon tank precisely so the generator can run several days through a hurricane without a refill truck showing up, which is unlikely to happen quickly right after a storm anyway.
Energy content and output
The two fuels do not carry the same energy per unit, and it shows up in the specs. Propane packs more energy by volume, so a given generator often lists a slightly higher power rating on propane than on the same unit running natural gas. The practical effect is usually small for a properly sized home unit, but it can matter at the top of a generator’s range or when you are trying to cover a large air conditioning load. This is another reason correct sizing comes first. If you have not worked out your load yet, start with our guide to sizing a home standby generator before you lock in a fuel.
Which First Coast homes use which
Patterns follow the utility map more than anything. Older Duval neighborhoods on JEA gas and newer master-planned St. Johns communities on TECO tend to land on natural gas because the infrastructure is there. Established Jacksonville homes with an existing gas line are strong natural gas candidates. Rural Clay County, wooded Nassau parcels, and beach-area lots without a main lean propane. In Fernandina Beach, it can go either way depending on whether Florida Public Utilities gas reaches the specific street, so it is worth confirming rather than assuming.
What to ask the installer
- Does a natural gas main reach my address, and which utility serves it here?
- Is my existing gas meter and line sized for a generator on top of my current appliances, or does it need an upgrade?
- If propane, what tank size covers my expected runtime, and above or below ground?
- What is the actual power output of the unit on my chosen fuel?
- Who handles the fuel connection, the electrical, and the permit?
There is no universally right answer between the two. The right fuel is the one your property can actually support, sized for the runtime you want. When you are ready, we can connect you with one vetted, licensed installer who serves the First Coast and will assess your site honestly. You may also find our standby versus portable generator comparison useful while you weigh options.