What’s the difference between Diesel Generators and Gasoline Generators

People and communities around the globe depend on electricity to power their lives. The uses for electricity are vast and include everything from lights and heat to computers, tools, and machines that run businesses of all types.

When the electricity goes down, what options do people have?

The most logical options are diesel and gasoline power generators. When considering what type of generator to buy, shoppers can select from a variety of choices. Two of the most popular generator types include gasoline and diesel powered options for the home and business. When purchasing a generator, make sure to weigh the pros and cons of each generator type and how each type performs under certain circumstances.

Before we start, let’s level set our understanding of what a diesel generator is and what a gasoline generator is.  Once we define each of these types of generators, we will look at the uses of generators benefits of each.

Whether you need a diesel generator or a gasoline generator, there are a lot of great options to choose from depending on why you need it. The exact type of generator you need depends on the specific application you plan to use it for.

When purchasing a generator, there are many things you should consider before you buy such as how much power production the generator is going to require based on what you want to plug into it and for how long.  To know this, you will need to understand how many watts the devices you want to connect will require operating.

It’s important to note that when you are using a generator, whether it’s a diesel or gasoline generator, you should not exceed the stated capacity of the generator. This can both damage the generator or your devices and most importantly, you may be frustrated that the generator you choose won’t meet you needs when you need it most.

What is a diesel Generator?

A diesel generator is the combination of a diesel engine with an electric generator (often an alternator) to generate electrical energy.

Diesel generating sets are used in places without connection to a power grid, or as emergency power-supply if the grid fails, as well as for more complex applications such as peak-lopping, grid support, and export to the power grid. Proper sizing of diesel generators is critical to avoid low-load or a shortage of power.

What is a Gasoline Generator?

A gasoline generator is the combination of a gasoline engine with an electric generator (often an alternator) to generate electrical energy.

Similar to diesel generators, gasoline generators are also used in remote places without a direct connection to the power grid, or as an emergency backup if the power grid fails for whatever reason.

Types & Uses for Gasoline & Diesel Generators

Camping Generators

If you like to get out in the great outdoors with friends and family and need a good reliable power source, Camping generators and new inverter technology have made these once noisy generators run a lot quieter which is especially important if you are camping in campgrounds where you may have neighbors to consider.

Portable Home Generators

If you live in a place that has frequent power outages such as remote cabins or home on islands, portable home generators can come in handy when the power goes out. These are generally used as backup generators in a home setting where power can be provided by running multiple extension cords into the home from the generator or by connecting the generator to a transfer switch for supplemental power.

Portable Industrial Generators

When you need a generator for business or industrial use, you will want to spend a little more to get a more durable generator than portable home generators. The best use for these is on construction sites or as backup power for a business

Standby Home Generators

Unlike a portable home generator, standby home generators are typically not moved once they are installed. These types of generators are larger than portable generators for the home and tend to be much more powerful. These types of generators are used for off-grid homes and remote outposts for construction sites or other business applications.

Comparing Gasoline and Diesel Generators

They both provide off-grid power or backup power when needed but diesel and gasoline generators have some distinct differences between them.

For starters, the most evident difference is how a diesel engine ignites the fuel in the cylinder as opposed to how a gasoline engine produces its combustion. In a gasoline engine, fuel is mixed with air, compressed by pistons and ignited by sparks from spark plugs. In a diesel engine, however, the air is compressed first, and then the fuel is injected.

The details below outlines some of the most important differences between diesel and a gasoline engine generators.

Fuel Consumption

Diesel engines are more fuel efficient than gasoline engines. This means longer running time when running at the same capacity. Some diesel engines consume up to half as much fuel as compatible gasoline generator engines.

This advantage can, of course, depend on the current price of diesel is, but for the most part, a diesel generator costs less over time to use.

Diesel generator engines generally also require less maintenance than gasoline engines. This is in part due to diesel engines not having spark plugs or carburetors.

Two fewer things to breakdown and no need to replace spark plugs or rebuild carburetors at any point in the life of your engine. Diesel engines also require less regular oil changes lowering the maintenance costs.

Diesel engines are a lot safer than gasoline engines, since there is no spark that could cause an explosion.

Power Production

The difference in power between a gasoline and a diesel generator is evident, as represented in the compression ratios of each.

A gasoline engine compression ratio falls anywhere between 8:1 to 12:1, whereas a diesel engine compression ratio falls anywhere from 14:1 to as high as 25:1.  This, in turn, leads to the diesel generator running more efficiently than a gasoline generator.

One area where gasoline generators outpace diesel generators is cold weather starts.

Diesel engines do not use a spark plug, relying on the compression of the air within the cylinder to cause ignition, as the heat generated, combusts the fuel present. In cold weather, this presents a problem because reaching the heat necessary for combustion to occur is more difficult.

The use of a glow plug, a wire with an electric current passing through it, can help circumvent this. This helps ignite the fuel, allowing the engine to start in cold weather. Once started, the engine should run fine.


The portability of gasoline and diesel generators is generally the same, with both types coming in models that can be easily moved to a location where they are needed most.

Overall, a diesel generator provides more power while using less fuel, making it a better investment in a portable form, even though gasoline models tend to be a little more lightweight.

Another plus for a gasoline generator is that fuel can be located almost anywhere, although diesel pumps at fuel stations are very common.


When comparing the durability of a gasoline generator and a diesel generator, a diesel generator requires less maintenance than a gasoline generator.

In addition to this, the cost of maintaining a diesel generator is less than for a gasoline generator.

Gasoline generators also tend to run hotter than their diesel counterparts, which leads to more wear and tear on the gasoline generator parts.

Another cause of wear and tear on a generator’s engine is knocking caused by the fuel/air mixture present in a gasoline generator’s cylinder prematurely igniting, a problem not found in diesel generators since no fuel is actually injected into the cylinder, only air.


As stated earlier, gasoline generators use spark plugs to ignite the fuel/air mixture used in the combustion process.

For obvious reasons, this can pose a danger if the equipment is not properly maintained. Another benefit of using diesel is its higher flashpoint, which means that it takes more heat to actually ignite any spilled fuel.

The noise level produced by generators is also of concern, especially on a diesel generator, as diesel engines tend to run louder than more conventional gasoline engines.

Newer generators, both gasoline and diesel, are quieter than their older predecessors.

Placing the generator in a soundproof box also helps reduce the overall noise pollution produced, although owners should properly ventilate the generator to reduce overheating.


When shopping for generators, consider maintenance levels between generator types.

The higher overall heat at which a gasoline generator operates means that the engine parts need replacement more often than those of a diesel generator.

With both types of generators, it is important to have regular maintenance performed.

This includes changing any filters and the engine oil, as well as running the engine until it is empty if the generator is not used for an extended period.


One final difference between a gasoline and a diesel generator is cost.

A comparable diesel generator typically costs more than a gas generator, mainly due to its more robust nature. Diesel generators are easier to maintain and last longer than gasoline generators of the same power production level.

The cost of a diesel generator can translate into real savings over time if properly maintained.

A gasoline generator can also last if properly maintained, but due to the more complex nature of a gasoline engine, and the heats involved, eventually a gasoline generator breaks down and needs replacement.


Power generators allow you to power your homes or businesses during outages or emergencies, or for use in places that are just not close to or on the power grid.

They are also great for outdoor activities, like camping, offroading, picnicking, or with your RV or camper. Depending on the output of the generator you choose, you can power all kinds of useful devices like kitchen appliances, bathroom accessories like hair dryers, TVs, radios, computers, and tools.

Generators are probably most used in commercial and business applications like remote worksites and new construction sites not close or connected to the power grid.

Knowing the difference between a gasoline and a diesel generator is a good first step in the buying process. Diesel generators are generally more productive and affordable over the long run, but gasoline generators are quieter and have a few other advantages.

It is important for buyers to consider this crucial decision before purchasing a generator.

I hope this guide has been helpful.

Author: Energy Solutions Editor

Writing about modern energy solutions & off grid living including gasoline and diesel generators and wind, solar and geo thermal solutions.

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