A dual-fuel conversion system can offer some of the fuel- and emissions-saving benefits of a natural gas engine without going out and buying a brand-new truck.

Recent changes in Environmental Protection Agency rules that went into effect in 2011 made it easier for companies to certify conversions that allow diesel engines to burn a mixture of natural gas and diesel fuel. They may displace 50%, 60% or more of the diesel fuel with cleaner-burning, cheaper natural gas.

One of the key benefits of these systems is if a truck needs to run in an area where there is not a natural gas fueling infrastructure, the truck can run on straight diesel fuel.

Here are some of the companies offering these systems:

American Power Group

Before getting into the U.S. transportation market, APG offered dual-fuel systems for stationary power generation and for transportation uses in other countries. It has teamed up with the WheelTime network to help it market and install its Vehicular Turbocharged Natural Gas System. In addition, Ervin Equipment and Fitzgerald are providing glider kits with APG’s dual-fuel system. APG has EPA certification for more than 200 engine families.

Clean Air Power

Clean Air Power is a UK firm that is bringing its Genesis-EDGE Dual-Fuel conversion unit to the U.S. It’s working with UPS to put the system on 10 Mack MP8-powered tractors for fleet testing. Clean Air Power also has a Caterpillar C15 system that can be fitted to existing trucks or to new trucks using a glider kit.


The EcoDual MAX/SR system enables heavy-duty diesel trucks to displace an average of 60% to 70% of their diesel fuel use with natural gas. MAX/SR is available for Cummins ISX engines produced from 2004 to 2009. EcoDual is working on certification for other engines.

Converting to 100% natural gas:

Omnitek Engineering Corp. offers a diesel-to-100% natural gas system. “Diesel dual fuel is an exciting prospect, however, success and customer acceptance is limited,” the company says. “The promise of 50% to 60% diesel replacement is very attractive, but in reality savings in dollars will be more like 15% - 40% range.”

The system converts existing in-use diesel engines into compressed natural gas or liquefied natural gas – at a fraction of the cost of new engines, Omnitek says. It has more than 5,000 engine conversions worldwide but is still getting ramped up in the U.S. So far it has certification for the International DT-466 and says it will have approvals for several more engines by the end of this year and into 2014.

Omnitek is working with the Puget Sound Clean Air Agency for a pilot project to demonstrate its diesel-to-natural gas engine conversion technology for drayage trucks serving the Port of Seattle, Wash.

Learn more about alternative fuel conversions at www.epa.gov/otaq/consumer/fuels/altfuels/altfuels.htm

About the author
Deborah Lockridge

Deborah Lockridge

Editor and Associate Publisher

Reporting on trucking since 1990, Deborah is known for her award-winning magazine editorials and in-depth features on diverse issues, from the driver shortage to maintenance to rapidly changing technology.

View Bio