The fuel decision is made before the generator is bought, and it is hard to change afterwards. A natural gas generator is plumbed to the house; a propane generator needs a tank in the yard. This page is the comparison — what each fuel costs to install, what it costs to run, and which one fits a house that sits empty half the year.

The short answer

If your house has natural gas at the meter, use it — the fuel is already there, it never runs out, and the installation is a gas line, not a tank. If it does not, propane is the answer, and the tank is the decision: how big, where it sits, and how often it is filled. The whole-home cost range — $11,000–$17,000, installed and permitted — holds for either fuel; the difference is in the fuel work, not the generator.

One number to keep in mind: a 24 kW Generac Guardian burns about 306 cubic feet of natural gas an hour at full load, or about 3.9 gallons of propane an hour. At half load, the propane figure is about 2.5 gallons an hour. The fuel is the running cost; the generator is the purchase.

Figures last reviewed November 2026 · Sources: see ‘How we get our numbers’ on the About page.

Talking to an installer — where things stand:

We’re onboarding our Palm Beach County installer partner now, and the consultation request list is contacted first when scheduling opens. When you join the list, tell us which fuel your house has — it is the first thing the installer asks.

Call (561) 589-2937

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How each fuel gets to the generator

Natural gas arrives by pipe. The gas company runs a line to the meter, and the installer runs a line from the meter to the generator. The work is a trench or a run along the house, a regulator, and a connection. The cost in the county figures is $260–$820 to run the line.

Propane arrives by truck. A tank sits in the yard — above ground, or buried — and the installer runs a line from the tank to the generator. The cost in the county figures is $600–$2,500 for a tank and installation, more for a large or buried tank. The tank is the part that needs a permit, a setback, and a delivery schedule.

What the fuel work adds to the turnkey total

The fuel work is usually quoted separately from the generator, which is why it is the line that most often surprises. The full Palm Beach County cost breakdown.

Natural gas — $260–$820 to run the line. No tank, no deliveries, no refilling.
Propane — $600–$2,500 for a tank and installation, more for a large or buried tank. Plus the cost of the propane itself, which is bought by the delivery.

The runtime arithmetic

A propane tank is not filled to the top — it is filled to 80%, to leave room for expansion. A 250-gallon tank holds about 200 gallons of usable propane. At half load, a 24 kW unit burns about 2.5 gallons an hour — so a full 250-gallon tank runs about 80 hours. At full load, about 3.9 gallons an hour, or about 51 hours.

Natural gas has no tank and no arithmetic — it runs as long as the gas company delivers. In a hurricane, the gas supply has historically kept running in this county, but it is not guaranteed; a propane tank is yours, and it runs until it is empty.

The size question is a fuel question too. The generator sizing guide.

Fuel cost per unit: what to ask your supplier

Propane is priced by the gallon, and the price varies by supplier and by season. Before you buy, ask three questions:

What is the price per gallon, and does it change with the season?
What is the delivery charge, and is there a minimum?
How often can you deliver in an outage — and what is the wait?

Natural gas is priced by the therm, on the gas bill. Ask the gas company one question: is the meter sized for the generator’s draw at full load, or does the meter need upgrading? A meter upgrade is a cost, and it is better found before the installation than during it.

Permits, placement, and the tank in the yard

The fuel permit covers the gas line or the propane tank, and the tank’s placement has its own setbacks: at least 5 feet from the house and 10 feet from the property line. The setbacks are part of the permit application, and the inspector checks them. Permits and HOA approval, step by step.

A buried tank avoids the setback problem and the sight of a tank in the yard — but it costs more, and it needs a different permit. An above-ground tank is cheaper and easier to inspect, but it is visible, and the HOA may have a view on where it sits.

If the house sits empty half the year, fuel is an autonomy question

A house that sits empty needs a fuel supply that lasts until you return — or a monitoring setup that tells you when it will not. Natural gas has no tank to empty. Propane has a tank that does empty, and the question is how long it lasts: a 250-gallon tank at half load is about 80 hours, or a little over three days. If you are away for months, the tank needs to be full when you leave, and the monitoring needs to tell you if it runs.

Two guides for the empty house: After the storm: running your generator through an outage and Remote monitoring: knowing your generator ran while you’re up north.

Get the numbers in one file

The free Cost Guide has the fuel work priced for both fuels, the runtime arithmetic, and the checklist for your consultation.

Send me the Cost Guide

Fuel questions, answered

Can I switch fuels later?

You can — but it means a new fuel line or a new tank, a new permit, and a conversion of the generator. The fuel is a twenty-year decision, like the brand. Choose it on what is at the house: gas at the meter, or a tank in the yard.

How long will a propane tank last in an outage?

A 250-gallon tank, filled to 80%, holds about 200 gallons. At half load, a 24 kW unit burns about 2.5 gallons an hour — about 80 hours, or a little over three days. At full load, about 3.9 gallons an hour — about 51 hours. The load is the number that matters; the tank is the number that limits it.

Does natural gas ever go out in a hurricane?

It has historically kept running in this county, but it is not guaranteed. A gas line can be damaged, and a gas company can shut off supply in a damaged area. Propane is yours — it runs until the tank is empty. Neither is a certainty; the difference is who controls the supply.

Is a buried propane tank worth it?

It costs more, and it needs a different permit — but it avoids the setbacks, the sight of a tank, and the HOA’s view on where it sits. For a house where the yard is the view, it is often worth it. For a house where the tank can sit out of sight, the above-ground tank is the cheaper answer.

What does the fuel work cost?

Natural gas, $260–$820 to run the line. Propane, $600–$2,500 for a tank and installation, more for a large or buried tank. The fuel work is usually quoted separately from the generator — which is why it is the line to check on any quote. The full Palm Beach County cost breakdown.

Palm Beach Backup Power is an independent information service. We are not a generator installer. These figures are published estimates, not quotes — the number for your home comes from your installer’s written quote.

Propane or natural gas: which fuel should your standby generator use?