Natural Gas vs Propane Generators: Fuel Type Comparison for Commercial Applications

Fuel selection is one of the most important decisions when specifying a commercial standby generator. The two most common fuel options for commercial applications are natural gas (NG) and propane (LPG/LP). Each has distinct advantages depending on your facility's location, infrastructure and operational requirements.

Natural Gas Generators

Natural gas generators connect directly to your facility's existing gas supply line. This provides an effectively unlimited fuel supply — as long as the gas utility maintains service, your generator can run indefinitely. This makes natural gas the preferred fuel for extended outage scenarios and critical facilities that cannot afford to run out of fuel.

Advantages of natural gas:

• Unlimited fuel supply through utility connection — no refuelling required
• Lower fuel cost per kWh compared to propane in most regions
• No on-site fuel storage tanks required
• Cleaner burning with lower emissions than diesel
• Fuel does not degrade over time (unlike diesel or gasoline)

Considerations:

• Requires existing natural gas service at your facility
• Gas line sizing may need to be upgraded for larger generators
• Natural gas supply can be disrupted during severe events (earthquakes, major storms)
• Slightly lower power output compared to the same engine running on propane

Propane (LPG) Generators

Propane generators draw fuel from on-site storage tanks, typically 500 to 1,000 gallon tanks for residential-commercial applications and larger tanks for industrial installations. The fuel is stored under pressure as a liquid and vaporises when released to the generator.

Advantages of propane:

• Available anywhere — no utility connection required
• On-site storage means independence from utility infrastructure
• Higher energy density produces slightly more power per engine displacement
• Long shelf life — propane does not degrade like diesel or gasoline
• Ideal for rural locations, agricultural operations and remote facilities

Considerations:

• Requires on-site storage tank (permitted, installed and maintained)
• Finite fuel supply — must be refilled by propane delivery service
• Higher fuel cost per kWh than natural gas in most markets
• Tank installation adds to total project cost
• Delivery access required for refuelling

Bi-Fuel: The Best of Both

Many modern commercial generators offer bi-fuel capability, allowing the unit to run on either natural gas or propane. This provides maximum flexibility — connect to natural gas as your primary fuel with propane as a backup, or deploy the generator at different sites with different fuel availability.

Bi-fuel generators typically include a fuel selector switch and are factory-configured with jets and regulators for both fuel types. The slight cost premium for bi-fuel capability is often justified by the operational flexibility.

Cost Comparison

At current US energy prices, natural gas is typically the most economical fuel for continuous or frequent generator operation. Propane costs approximately 20-40% more per kWh of electricity generated. However, if your facility does not have natural gas service, the cost of installing a new gas line may exceed the lifetime fuel savings — making propane the more cost-effective choice.

For facilities with natural gas service: choose natural gas for lowest operating cost and unlimited fuel supply. For rural facilities, remote sites or locations without natural gas: choose propane for fuel independence and availability. For maximum flexibility: choose bi-fuel and connect to whichever fuel source is available at your location.