What are Dual and Tri-Fuel Generators & How They Work


In Brief: What are Dual and Tri-Fuel Generators

A dual fuel generator is a generator that can work on two fuel sources, usually gasoline and propane. A tri-fuel generator can run on three fuel sources, typically gasoline, propane, and natural gas.

An electric generator produces electrical energy from combusting fuel.

It helps you run all your electrical devices in the case of a power outage or when you need extra power to run specific tools.

If you are unable to get the required fuel source, you may remain without power to operate your device.

Hence, going for a dual or tri-fuel generator gives you the assurance and flexibility you need.

In this article, we will help you understand the working, benefits, and limitations of dual and tri-fuel generators.

What is a Dual / Tri-fuel Generator?

A dual fuel generator can work on more than two fuel types, while a tri-fuel generate can operate on three fuel sources.

In both cases, if you are run out of one kind of fuel, you can easily use the other one you have, unlike single fuel generators, which can only operate on one type of fuel.

Dual fuel generators mostly use gasoline or propane as their energy source, while tri-fuel generators can work well with gasoline, propane, and natural gas.

Generators that run on diesel are known to be the most efficient, but it’s hard to find dual or tri-fuel generators operating on diesel.

Next to diesel, propane sources are quite capable, followed by gasoline and natural gas.

How Dual / Tri-fuel Generator Work?

Dual generators work with single fuel to draw their energy and produce electricity.

It is also capable of running on two types of fuels at the same time when mixed in appropriate quantities.

The in-built governor system in the generator adds the secondary fuel source to the primary one until the right mixture for efficient working is attained.

For example, a ratio of 3:1 natural gas diesel fuel is ideal for an efficient system.

If the engine load is increased, the governor will add more diesel and readjust the fuel ratio until the engine is operating at peak efficiency.

You can manually choose the fuel selector switch that comes along with the generator to change from one fuel to another.

After selecting the fuel type, open the fuel valve and add the fuel. Switch on the ignition and battery switches for the generator to start running.

The mechanical power produced is then forced into a circuit and induces an electrical current.

The electric current is directed through copper wires to power external machines, devices, or entire electrical systems.

Here’s a quick video on how to start up your dual fuel generator —

The tri-fuel generator operates more or less in a similar way as the dual generators except that it can run in three energy sources rather than two.

Why there is a need for dual fuel/tri-fuel generator

Here, we will discuss a few reasons why you might need a dual fuel or tri-fuel generator for yourself.

The convenience of choosing fuel

One of the biggest reasons dual/tri-fuel generator units are desirable is they are convenient to handle and easy to obtain the fuel source.

Gasoline and diesel are readily available in many places, and it’s comfortable to change the fuel source depending on its availability.

If you run out of one fuel source while using the generator, you can easily switch to another source and continue using the generator.

They are also very convenient if you want to take the portable generator on the road while camping or traveling.


Dual/tri generators are flexible as you can change the fuel type according to the weather conditions.

You can use propane in summers as the volume of propane is directly proportional to temperature. It becomes dense during winters and expands during summers.

In winter, you can start the generator with gas and later change to propane.

You can convert a dual fuel generator into a tri-fuel system using the conversion kits with minimal effort.

Helpful in Contingency Situations

During emergencies like hurricanes, earthquakes, storms, it is hard to get propane or get natural gas delivery to your home through the piping system.

If you use a single fuel generator operating on any one of the above fuel sources, you won’t be able to use your generator as a back-up anymore.

In these situations, dual/tri-fuel generators offer the best contingency as you can simply use the stored gasoline or propane or diesel as a back-up.

More Reliable

Dual or tri-fuel generator systems are highly reliable as different fuels can be stored and used whenever you want.

Propane can be stored longer in a tank and can be used whenever required. Besides, if the container is sealed correctly, there is no need to worry about spills or fire break out.

The tanks can also easily be refilled or exchanged.

If your house has a natural gas supply, you don’t need to worry about running out of fuel anymore, as you can use natural gas instead of buying extra gasoline or propane.

Systems running on gas don’t need to be stored on-site, which eliminates maintenance and space restrictions.

This way, you can be ensured with a continuous and safe power supply to your home when needed.

Environmental friendly

If you are concerned about the harmful gases emitted due to diesel combustion, you need to get dual/tri generator systems.

Dual/tri systems can operate on natural gas or propane, which burns cleaner than diesel. They can also be mixed with diesel, which produces less emission than the generators powered solely by diesel.

Limitations of dual / tri-fuel generators

Though dual/tri-fuel generators offer a lot of advantages over conventional systems, they have their own set of disadvantages.

In this section, we will dive deep into some of the limitations of the dual/tri-fuel generators.

High Cost

Dual/tri-fuel generators are not economical if you live in an area with almost no power outages.

Further, if your home doesn’t have an existing natural gas line supply, then getting one will cost you extra money.

Variable Efficiency

The type of fuel you use for your generator can affect its efficiency. For example, natural gas is not very energy-dense.

Because of that, most tri-fuel generators produce less wattage when running on natural gas than when running on gasoline or propane.

Further, a dual system can function well on any one of the fuel sources in the absence of others. But, to start the engine, only some fuels are capable.

You just need a mere temperature of 500-700 degrees of Fahrenheit to start burning diesel while the natural gas will not burn until 1,150-1,200 F of temperature is provided.

Because of this, you can quickly start a system running alone on diesel, but you can’t start a system functioning alone on natural gas.

For this, you might need to use diesel to start the system and later switch to natural gas for power production.

Short shelf life

Gasoline might be difficult to obtain during storms or emergencies and have a short shelf life.

Moreover, if you store gasoline for more prolonged periods, it might go stale and compromise the proper functioning of the generator, making it less reliable.

Safety concern

Gasoline is prone to spilling and potential fire outbreak if not appropriately handled.

So, if you are storing gasoline as one of the fuel sources, you need to take extra precautions.

Diesel stored in tanks is prone to groundwater contamination.


Dual/tri-fuel generators are becoming popular nowadays due to their flexibility, reliability, and convenience than conventional single fuel systems.

There is still a debate around if you should get one.

Here, we have done our best to explain the functioning of the dual/tri-fuel generators along with their benefits and limitations.

We hope it will help guide you better if you decide to buy a dual or tri-fuel generator.

About Steven

Steven is an engineering graduate with amazing zeal and enthusiasm. He is fascinated by solar power and has set up a small solar plant at his rooftop.