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Advantages of Diesel Generators over Natural Gas/Liquid Propane

Natural gas or liquid Propane and diesel generators are the two basic generator types homeowners can use to power their homes either for full-time electricity or for a backup generator during a power outage event.

Advantages & Disadvantages of Generator Types

There are several advantages of diesel generators over natural gas and liquid propane generator. For the purpose of the comparison, Natural Gas & Liquid Propane will be lumped together with a couple of exceptions that will be explained when needed.

While both can provide reliable standby power for your home they are uniquely different in performance, operating cost, the life of the product, and cost. I will point out the advantages and disadvantages of each generator type.

Greenfield Energy's HERO Diesel Generator Interior

Natural Gas & Propane Fueled Generators

Natural gas and propane-fueled generators are popular choices for many homeowners looking for backup power. The generators are easily available to purchase at your local hardware store.

Easy access does not always mean convenience, especially when compared with diesel-fueled generators. Review the pros and cons of natural gas and propane generators before considering your other options.

Advantages of Natural Gas & Propane Generators

Here are some Advantages of Natural Gas fueled generators:

  1. The lower initial cost of generators (many add-on costs will be outlined later)
  2. Available natural gas fuel supply by gas company pipelines. (Liquid propane fuel sources differ greatly from Natural gas supplied by the utility.)
  3. Smaller footprint/size

7 Disadvantages of Natural Gas & Propane Generators

Here are seven of the Disadvantages of Natural Gas Generators.

#1: Add on Costs of Installation & Fuel Storage

Add-on costs of installation and fuel storage for natural gas generators can be a huge downside. A certified natural gas pipe fitter installation can be several thousand dollars.

Typically the gas meter and the electrical meter are positioned on opposite sides of the house. For liquid propane fuel, a propane tank will need to be installed or upgraded to accommodate the volume of fuel to run the generator.

Large propane tanks need to be located away from the house or need to be buried this can cost $5,000 or more.

#2: Fuel Source Loss or Damage

Fuel source loss or damage can be devastating to natural gas generations. Natural gas fuel supply can be damaged at your home or from the utility cutting off fuel to your generator when you need it most.

Liquid Propane tanks run out quickly due to the large and inefficient consumption of the gaseous generators. Delivery of Liquid Propane Gas will have to be scheduled. Sharing the Liquid Propane with appliances such as a stove, oven, hot water heater, and furnace will shorten the runtime of the generator.

#3: Extremely Explosive Fuel Source

Natural gas generators rely on an extremely explosive fuel source. Leaks at fittings or ruptured pipes near your home are very dangerous situations.

Any leaks in the propane tank may not be detected until the unit is run during an outage causing the unit shutdown when needed the most.

#4: High Maintenance & Fuel Costs

Another disadvantage to some generators is their high maintenance and fuel costs. Natural Gas and propane generators require oil changes every 100 hours of service while diesel generators maintenance is required every 500 hours of service. (Note: maintaining a detailed maintenance log will e needed for any warranty repairs.)

Gas burning engines require spark plugs and a carburetor which also have regular maintenance adding to the cost. Natural gas/Propane generators are very inefficient and run at 3600 rpm. They consume almost 5 times the amount of fuel as a diesel generator with identical power output.

#5: Natural Gas & Liquid Propane Generators are Noisy!

Natural Gas/ Liquid Propane generators are very noisy for 2 reasons:

  1. Engines are small, so in order to generate the power outputs required they run at 3600 RPM.
  2. Engines are AIR Cooled so they require huge amounts of air to be pulled through the engine compartment to attempt to keep the cool.
#6: Limited Warranties

Limited warranties can be a big selling point in any large appliance purchase. Many home generator manufacturers will advertise 5 & 10-year warranties to “close the deal”.

These warranties are very restrictive and require the homeowner to be extremely diligent in keeping out rodents, bees, wasps, and other vermin while keeping extensive maintenance records in order to utilize the warranty when needed.

Also, an extended power outage might take the natural gas/propane out of the warranty since these generators are only designed for short runtimes (2-3 days maximum).

#7: Shorter Lifetimes

One of the biggest disadvantages of natural gas or liquid propane generators are their shorter lifetimes in comparison to diesel generators. Natural Gas and Liquid Propane residential generators are designed to run at 3600 RPMs. This allows a smaller engine to produce power at a higher KW output. This is a significant saving on the purchase price of the generator.

HOWEVER, these engine runs significantly hotter and is not designed to run for long periods of time. The generator may need to be replaced after 1 or 2 major outages.

Diesel Fueled Generators

Diesel-fueled generators have evolved over the last two decades. Tougher emissions standards have made Diesel engines much more efficient and cleaner. Diesel generators are the preferred backup power source for hospitals because of their independent fuel source and reliable power output for extended periods of time.

Greenfield Energy's HERO Diesel Generator Exterior

Advantages of Diesel Generators

Here are some Advantages of Diesel Generators:

#1: Reliable Power Output

Diesel engines are designed to run for long periods of time with extended maintenance intervals. Diesel engines are compression engines that do not have spark plugs or carburetors like Natural Gas engines.

The simple design allows diesel generators to perform only when needed.

#2: Lower Cost of Lifetime Operation and Maintenance

Diesel fuel is much denser than Natural Gas or Liquid Propane thus it is can produce more power. While the cost of diesel may be slightly higher than natural gas it will cost less to operate and maintain a diesel generator than a natural gas generator over its lifetime.

Maintenance intervals of diesel generators are every 500 hours as compared to natural gas generators’ 100-hour maintenance intervals. A diesel generator also has fewer components that need to be maintained.

#3: Independent Fuel Source & Availability

Diesel generators typically have an independent fuel source in the “sub-base fuel tank”. This means that there is a fuel tank underneath the generator.

Fuel source availability is typically why diesel generators are considered too bulky for residential applications. When in fact these attached fuel tank is the biggest advantage of diesel generators.

Diesel is readily available in all gas stations. If an extended outage depletes the sub-base tank, homeowners can refuel themselves if needed. The sub-base is not affected by outside natural gas utility or reliant on Propane deliveries.

#4: Home Owner Friendly

If you are looking for a home owner-friendly generator option diesel engine generators are a great option.

  • Compact Design: newer designed diesel generators allows homeowners to install diesel generators in close proximity to the home.
  • Quiet Operation: diesel generators operate at 1800 RPM thus they are much quieter than the 3600 RPM natural gas generator. Diesel generators are also liquid-cooled, so they do not require the same volume of air to be pulled through the engine compartment.
  • Cleaner: new emission requirements have made diesel generators cleaner for the environment than natural gas generators. Natural gas engines emit more carbon dioxide than diesel generators.
#5: Lifetime Generator Warranty

Compared to the limited warranties of natural gas and liquid propane generators, diesel generators have valuable lifetime warranties to back up owners.

Diesel generators can run for extended power outages without voiding the warranty. Diesel generators are designed to run for extended periods of time and will last 15 plus years when maintained properly

Untrue, Perceived Disadvantages of Diesel Generators

There is a lot of talk about the cons of having a diesel generator. Here are a few perceived disadvantages of Diesel Generators compared to the reality of operating natural gas and liquid propane generators.


While the initial purchase price of a diesel generator can be more than a natural gas unit there are several factors that negate this initial price difference:

  • Increased installation cost of natural gas or liquid propane units
    • Propane tank cost and installation
    • Gas technician for gas connections
    • Additional permitting for gas connections
  • Increased operational cost of natural gas or liquid propane units
    • Diesel fuel consumption is approximately 5 times less than that of natural gas or liquid propane
  • Maintenance cost is about 5 times less than natural gas generators
  • The lifetime of a Diesel generator will outlast natural gas and liquid propane generators by 2 to 3 to one. Effectively doubling or tripling the cost of natural gas/propane generators over the lifetime of a diesel generator.
Size & Noise

The size and noise of diesel-powered generators compared to propane and natural gas units is an old argument. Diesel generators have diminished these points by becoming both more efficient and smaller while producing the same amount of power.

  • Diesel generators are quieter than natural gas/liquid propane generators.
  • 1800 RPM liquid-cooled engine is quieter than a 3600 RPM air-cooled engine.

In short, diesel generators are quieter and cheaper to operate and maintain than traditional liquid propane or natural gas units. If you would like to learn more about the clear advantages of a diesel-powered system, contact the sales representatives at Greenfield Energy.

Learn More About Assembly & Distribution for HERO, Greenfield’s Portable Diesel Generator