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As a result of providing the power of diesel with the many environmental benefits of natural gas, Generac has seen an increase in the interest and installation of its Bi-Fuel™* generators, largely due to their many advantages:

  • Extended run times
  • Environmentally friendly
  • Enhanced reliability
  • Ability to provide factory-tested and warranted units
  • Scalability as part of a Generac Modular Power System (MPS)

Bi-fuel generators provide end-users with the advantages of using both diesel and natural gas fuels while minimizing the disadvantages. Diesel fuel is used to start the engine and, as load is applied, the transition is made to a blend of diesel and natural gas. The diesel fuel remains necessary to maintain ignition of the natural gas, but in bi-fuel mode diesel consumption is only a small percentage of full diesel operation.  Utility-supplied natural gas provides extended run times, which can be a significant benefit during major storms or other events where diesel fuel deliveries can be compromised.

“The standard diesel governing system runs continuously; during sudden load changes, diesel instantly becomes the dominant fuel so the system reacts just like a typical diesel generator,” explained Mark Sweeney, Business Manager-North Central, Generac Industrial Power.

Bi-fuel generators also have lower diesel fuel management costs. With the EPA’s new regulations aimed at reducing emissions from diesel engines, the use of ultra-low sulfur diesel (ULSD) in mandated in all standby generator applications. ULSD goes through additional refining processes which makes it less stable than traditional diesel fuel. This requires the fuel to be polished more frequently to ensure the fuel does not degrade and/or clog the engine filters. With bi-fuel generators, less diesel fuel has to be stored on-site, resulting in lower costs.

At the same time, because on-site diesel fuel is still part of the system, reliability is improved. Should the natural gas supply be interrupted, the generator can run on 100% diesel fuel. The system will automatically and seamlessly switch to 100% diesel operation with no loss of power during the transition.

Generac Bi-Fuel™ generators meet the on-site fuel requirements for emergency systems as referenced in National Electric Code 700 and National Fire Prevention Association (NFPA) 110. Less on-site diesel fuel typically means easier permitting, and indoor fuel installations with capacity limits per NFPA or local codes become a viable option.

“Generac is the only manufacturer supplying bi-fuel standby generators directly from the factory, providing the key advantages of factory testing and a factory warranty,” said Sweeney. “Other manufacturers have to convert their generators to bi-fuel by adding third-party after-market equipment which can lead to problems. There is also the question of responsibility should something malfunction on the generator,” he added.

The market has shown significant interest toward products that burn inherently clean natural gas as an alternative to diesel solutions. Bi-fuel generators utilize up to 75% clean burning natural gas providing the market with another viable fuel option. Though natural gas is very clean burning in many respects, natural gas combustion does produce an increase in CO emissions. Generac Bi-Fuel™ units remove this additional CO with an oxidizing catalyst integrated into the generators muffler. Generac also ensures the Bi-Fuel™ units are operating within the full compliance of EPA emission limits, including CO emissions. This factory verified approach ensures customers will not have EPA compliance issues that may be problematic for third-party after-market equipment that don’t follow a similar process.

Finally, Bi-Fuel™ generators can be used as part of Generac’s innovative MPS. While it is well-known Generac’s MPS provides redundancy, flexibility and scalability in a modular type paralleling system, MPS also provides the ability to mix and match gensets. “Our Bi-Fuel™ gensets can be paralleled with other bi-fuel, diesel or natural gas units, providing customers with a variety of possible solutions,” said Sweeney.

Most recently, 3 x 600kW Generac Bi-Fuel™ generators were installed at a Midwest natural gas utility, as the customer wanted to obtain the benefits of running cleaner natural gas while still meeting the code requirements for on-site fuel storage.

If you would like more information about Generac’s Bi-Fuel™ generators, contact your local Generac Industrial Power Distributor/Dealer.  You may also call 1-844-ASK-GNRC or email

*Some manufacturers refer to bi-fuel and dual-fuel engines interchangeably. Generac uses the term bi-fuel for the simultaneous combustion of both diesel and natural gas fuels, whereas dual-fuel is used to describe a system in which liquid propane vapor serves as a backup fuel source in a natural gas system.

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Posted by: Bret Grimes on March 30, 2016
Filed under: Generac, Generators