Top 4 Most Common Types of Generator Fuels

Residential Generator

When you’re shopping for a generator, it’s easy to get caught up in brand names or total wattage. But there is one decision that actually dictates how your life or business will look during a blackout: What is the best fuel to use for a generator?

The fuel you choose doesn’t just power the generator; it determines how easy it is to refuel during a storm and, ultimately, how reliable that system will be when the grid goes dark.

While many assume all generators are comparable, the choice of fuel source defines the reliability and long-term performance of your system. A setup that works perfectly for a suburban home might be a total disaster for a medical facility or a large warehouse.

In this article, we’re breaking down the four most common generator fuel types. We’ll look at the pros, cons, and the best-fit scenarios for each so you can make a confident choice for your property’s power needs.

Why Generator Fuel Choice Is Important?

Generator fuel choice affects more than just runtime. It impacts:

How long can the generator run without refueling
How easy is fuel to store or access
Maintenance and engine wear
Safety considerations
Operating costs over time
Performance during long outages

For example, a fuel that works well for a small portable generator may not be a good fit for a large commercial backup system. The right fuel depends on how you plan to use the generator and what level of reliability you need.

1. Diesel Generators

How Diesel Generators Work?

Diesel generators are a common choice for commercial facilities that need reliable power.

The engine compresses air until it gets hot enough to ignite the fuel without spark plugs. This design is part of why diesel engines tend to be strong and long-lasting.

Pros of Diesel Generator Fuel

High reliability: Diesel generators are built for continuous use. They perform well under heavy loads and are often used in facilities where power must stay on to support safety, essential services, or critical systems.
Fuel efficiency: Diesel engines typically use less fuel than gasoline engines when producing the same amount of power.
Exceptional Engine Durability: Diesel engines excel in high-demand settings, offering the reliable, long-term performance required by critical infrastructure and heavy commercial operations.
Strong performance under load: Diesel generators handle sudden power demands well, which is important for elevators, HVAC (Heating, Ventilation, and Air Conditioning) systems, and industrial equipment.

Cons of Diesel Generator Fuel

Fuel storage requirements: Diesel fuel must be stored on-site in tanks. This requires space, monitoring, and proper handling.
Fuel degradation: Diesel can break down over time if it sits unused. Without additives or regular fuel replacement, this can lead to clogged filters and engine problems.
Noise and emissions: Diesel generators tend to be louder and produce more emissions than other fuel types.
Higher upfront cost: Diesel generators often cost more to purchase and maintain than smaller gasoline or propane units.

Best Use for Diesel Generators

Diesel is often the best fuel for commercial generators that need to run for long hours or support large electrical loads. It is less common for residential use, but widely used in:

Hospitals
Assisted Living Facilities
High-rise buildings
Warehouses and industrial sites

2. Gasoline Generators

Types of Generator Fuels

How Gasoline Generators Work?

Gasoline generators are usually portable or small standby units. They run on standard gasoline, the same fuel used in most cars.

Because these engines work just like the one in your car, they’re much less of a mystery to maintain.

Pros of Gasoline Generator Fuel

Easy to find: Gasoline is widely available at gas stations.
Lower upfront cost: Gasoline generators are often less expensive than other alternatives.
Good for temporary use: Many gasoline generators are portable and suited for short-term power needs.

Cons of Gasoline Generator Fuel

Short fuel shelf life: Gasoline can degrade after a few months. If it is stored without stabilizers, it can cause starting and performance problems with the generator.
Higher fire risk: Gasoline is highly flammable and requires careful storage and handling.
Less efficient: Gasoline engines usually burn more fuel than diesel or propane for the same power output.
Not ideal for long outages: Refueling during extended outages can be difficult, especially when gas stations lose power.

Best Use for Gasoline Generators

Gasoline generators are best for short-term or occasional use, such as:

Portable generators for small jobs
Temporary backup power
Recreational use

Hence, they are generally not recommended for long-term home standby or commercial backup systems.

3. Propane Generators

How Propane Generators Work?

Propane generators run on liquid propane (LP), which is stored in pressurized tanks. Propane is a clean-burning fuel and is commonly used in residential standby generators.

Propane systems can be installed with large tanks that provide extended runtime during outages.

Pros of Propane Generator Fuel

Clean burning: Propane produces fewer emissions than gasoline or diesel, which helps reduce engine wear and is environmentally friendly.
Long fuel shelf life: Propane does not degrade over time, making it ideal for backup systems that sit unused for long periods.
Quiet operation: Propane generators tend to run quieter than diesel units.
Reliable in cold weather: Propane performs well in a wide range of temperatures.

Cons of Propane Generator Fuel

Fuel storage required: Propane requires on-site tanks, which take up space and must be monitored.
Tank size limits runtime: Once the tank is empty, the generator stops unless it can be refilled.
Fuel delivery needed: During widespread outages, propane delivery may be delayed.

Best Use for Propane Generators

Propane is a popular choice for home standby generators and some light commercial systems. It works well for:

Homes without natural gas service
Small commercial buildings
Facilities that want clean, stable fuel storage

4. Natural Gas Generators

How Natural Gas Generators Work

Natural gas generators connect directly to a utility gas line. Instead of storing fuel on-site, the generator draws fuel from the gas supply as needed.

This setup makes natural gas one of the most convenient fuel options for standby generators.

Pros of Natural Gas Generator Fuel

Continuous fuel supply: As long as the gas utility is operating, the generator can run without refueling.
No fuel storage needed: There is no need for tanks, which saves space and reduces safety concerns.
Clean burning: Natural gas burns cleaner than gasoline or diesel. This results in fewer emissions and a cleaner internal environment for your engine, which is a key factor in extending the life of your commercial backup system.
Lower long-term operating costs: Natural gas is often less expensive than other fuels over time.

Cons of Natural Gas Generator Fuel

Dependent on gas utility: If the gas supply is interrupted, the generator cannot run.
Lower energy density: Natural gas generators may produce slightly less power compared to diesel models of the same size.
Installation requirements: Natural gas systems require proper gas line capacity, which may need upgrades.

Best Use for Natural Gas Generators

Natural gas is one of the best generator fuels for homes and many commercial properties, especially where utility gas is reliable. It is commonly used for:

Residential standby generators
Office buildings
Retail properties
Small to mid-size commercial properties

Quick Comparison of Common Generator Fuel Types

Generator Fuel	Best Use Case	Key Strengths	Main Limitations
Diesel	Heavy-duty commercial and industrial generators	Handles large loads, long runtimes, and strong reliability	Requires fuel storage, higher noise, and emissions
Gasoline	Portable and short-term backup power	Easy to find, lower upfront cost	Short fuel shelf life, not ideal for long outages
Propane	Residential standby and light commercial use	Clean burning, long fuel shelf life, quieter operation	Limited by tank size, requires fuel delivery
Natural Gas	Standby generators with utility gas access	Continuous fuel supply, clean burning, no on-site storage	Depends on the gas utility, which produces slightly less power than diesel generators of similar size

How to Choose the Right Generator Fuel?

When choosing generator fuel, ask yourself:

Is this for a home or a business?
How long do I need the generator to run during an outage?
Do I want stored fuel or a continuous supply?
How much maintenance am I comfortable with?
What fuel is available at my location?

Homes often lean toward propane or natural gas, while businesses with critical power needs often choose diesel or natural gas.

Can You Use Any Fuel in Any Generator?

No. Generators are designed to run on specific fuel types, and using the wrong fuel can damage the engine or create safety risks. A generator’s mechanical design is built for a single fuel type.

Some generators are designed to operate on more than one fuel, such as propane and natural gas, but this only works when the generator is designed for that purpose. Standard single-fuel generators cannot safely switch fuels without manufacturer-approved components and setup.

Using the wrong fuel can lead to poor performance, engine damage, failed inspections, or voided warranties. Before operating a generator, it’s important to confirm the approved fuel type by checking the manufacturer’s documentation or consulting a generator professional.

Talk With a Generator Professional

Picking a fuel source is a huge decision, and it’s totally normal to feel a little overwhelmed, especially for a bigger setup that keeps your business running. You don’t have to sort it out by yourself.

Whether it’s safeguarding your home or protecting your livelihood, the team at A&A Power Generators has your back. We’ll break down the pros and cons of each option, factor in your power needs and local fuel availability, and help you land on the perfect fit. Check out our selection of available generators to get inspired.

Ready to move forward? Schedule a consultation today so you’re set and prepared before the next storm rolls in.

Top 4 Most Common Types of Generator Fuels

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