Generac Bi-Fuel™ generators use diesel as a pilot fuel to ignite the natural gas, eventually running primarily on natural gas, but they are also able to run on diesel fuel alone as conventional diesel generators typically operate. The natural gas provides extended running times not available on diesel-only generators. It also allows for reduced on-site diesel fuel storage, which means a smaller footprint and reduced diesel fuel maintenance.

Risk Mitigation via Fuel Redundancy

Generac Bi-Fuel generators mitigate refueling issues by operating primarily on utility-supplied natural gas. That means less on-site diesel fuel is required and running times will be greatly extended compared to diesel-only solutions.

Lower Total Cost of Ownership

Because natural gas costs less than diesel, fuel costs are significantly reduced over the long term. And since less on-site diesel fuel is required for long running times, installation, operational and maintenance costs are reduced.

Reduced Exhaust Emissions

Bi-fuel generators are cleaner and more environmentally friendly than diesel-only generators. They emit about 30% less nitrogen oxides and 50% less particulate matter than comparable diesel-only units.

Scalability as Part of a Modular Power System

Generac Bi-Fuel generators can be configured as part of a Modular Power System (MPS)—connected via integrated paralleling with other Generac generators. This makes the system scalable, meaning there is no need to install more power than you need.

Code Compliance

Generac Bi-Fuel generators meet the on-site fuel requirements for emergency systems as referenced in NEC700 and NFPA 110. Less on-site diesel fuel means easier permitting. And indoor fuel installations with capacity limits per NFPA or local codes become a viable option.


Generac Bi-Fuel generators are available up to 600 kW. That means you can choose the right single generator you need for your application, or get megawatt-level power from several generators connected in parallel as part of a Generac Modular Power System (MPS).

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What does Bi-Fuel™ refer to on standby generators?

Bi-Fuel is the simultaneous use of two different fuels to power the engine on a standby generator set. For Bi-Fuel operation, Generac uses a mixture of diesel fuel and natural gas (NG) in a diesel engine.

Is this different than dual-fuel?

Unfortunately, there is no clear answer. Both bi-fuel and dual-fuel are used within the industry to describe the concept of simultaneous combustion. In addition, both terms have also been applied to redundant fuel supplies where a secondary fuel is used only after the primary fuel is depleted or intentionally switched off. Therefore, it is important to understand how the terms are being used when comparing products. Generac uses the term Bi-Fuel for the simultaneous combustion of both fuels, and dual-fuel to describe a system in which liquid propane vapor serves as a backup fuel source in a natural gas system. This system is available as an option on a number of our gaseous fueled generators.

Is the Bi-Fuel concept a new technology?

No. Bi-Fuel has been around since the early 1900’s. However, early designs lacked adequate controls to make it very effective. Since that time, much development has occurred and control technology has advanced to make Bi-Fuel operation efficient and economical. Generac has developed a microprocessor-based control system that meets the challenge of maintaining an optimal balance of diesel and NG across the power range of the engine.

How does the Generac Bi-Fuel system work?

The engine starts on 100% diesel fuel. As soon as the coolant reaches a minimum temperature and the generator starts to accept load, natural gas is metered into the combustion air stream just before the turbocharger. As compression occurs, the diesel fuel ignites normally and provides the spark required to ignite the natural gas.

As load is applied, the amount of natural gas is increased and the amount of diesel fuel is decreased. We have conducted comprehensive testing and fuel ratio mapping to ensure safe, reliable operation under all combinations of load and temperature. Our PowerManager® control system continually monitors factors such as coolant temperature, intake manifold temperature and pressure, kW load and engine speed. The fuel mixture is instantly adjusted as needed. Under typical conditions, the operating fuel mixture will consist of up to 75% natural gas.

What are the benefits of Bi-Fuel?

  • Risk Mitigation via Fuel Redundancy
  • Lower Total Cost of Ownership
  • Scalability as Part of a Modular Power System
  • Code Compliance
  • Reduced Exhaust Emissions
  • EPA Compliance from the Factory
  • Longer Run Time

Is Bi-Fuel operation detrimental to the diesel engine?

No. In fact, the cleaner burning characteristics of NG result in less contamination of lubricating oil and reduced engine wear. In addition, peak cylinder pressures and exhaust temperatures, the key factors in engine wear, are lower during Bi-Fuel combustion than during diesel-only operation.

The PowerManager controller protects the engine by sensing the signature vibration signal created as conditions approach pre-ignition and immediately reduces the supply of natural gas before pre-ignition can occur. If the condition persists, natural gas is shut off, operation continues on 100% diesel fuel and an alert is issued. Extensive testing has shown that a Generac Bi-Fuel engine will have a longer operating life with extended service intervals and reduced maintenance costs than a standard diesel engine.

What happens if natural gas pressure drops or the supply is cut off?

The system will automatically and seamlessly switch to 100% diesel operation with no loss of power during the transition.

Can I monitor the amount of natural gas being used by the engine?

Yes. Our GenLink® software allows you to monitor all aspects of generator performance, either locally or remotely. GenLink can display natural gas flow both numerically and graphically.

How does the transient response of the Bi-Fuel engine compare to a standard diesel engine?

The Bi-Fuel engine’s transient load response is the same as a diesel engine. The standard diesel governing system is always active. During sudden load changes, diesel instantly becomes the dominant fuel so the engine will react just like a normal diesel engine. As a result, the Generac Bi-Fuel maintains the superior transient response of a diesel engine while providing the benefits of natural gas operation.

Are Generac Bi-Fuel generators prime power capable?

Yes, Bi-Fuel generators are prime power capable for applications outside of the U.S. & Canada due to EPA restrictions.

Are Generac’s Bi-Fuel generators UL Listed?

Yes. As with all Generac generators, our Bi-Fuel units are UL 2200 Listed for Stationary Engine Generator Assemblies. Both UL Listing and CSA Certification are available options on these units.

Does Yale/Chase Power Systems Generac support warranty and parts on Bi-Fuel generators?

Yes. Generac’s Bi-Fuel generators are backed by a full Generac factory warranty and product support.

Where can I purchase a generator?

Generators can be purchased through Yale/Chase Power Systems, the authorized Generac distributor for Southern California. We provide service from start to finish and have maintenance plans available. We have our own financing and specialized individuals to help with every step of the way.

Where is my generator made?

Generac generators are made in the United States. Manufactured by Generac Power Systems, Inc. in one of six manufacturing facilities in Wisconsin.

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