Dual Fuel for Diesel Engines
What does “Dual Fuel” mean?

In simple terms, Dual Fuel can be defined as the simultaneous combustion of two fuels. In the case of our Dual Fuel System, natural gas is utilized in conjunction with diesel fuel to operate the generator. After conversion, the generator is able to operate on either 100% diesel fuel, or alternately, on a mixture of diesel fuel and natural gas (or other combustible gases). At no time is the engine able to operate on natural gas exclusively. Dual fuel operation means the engine uses two fuels (gas and diesel oil) at the same time, as opposed to Bi-Fuel which would mean the engine could have the option of using either fuel separately, however in popular use Dual Fuel and Bi-Fuel are often used interchangeably.

Will my Generator have to be modified to operate on Dual Fuel?

No! The conversion technology has been designed to allow for in-field retrofit of diesel engines without the need to change or modify the design of the engine. The conversion hardware is mounted externally on the engine and does not require modification of the engine or alteration of any critical engine parameter.

What about my engine warranty?

Most OEM engine warranty programs do not prohibit the use of aftermarket parts or Technologies. In brief, the policy of OEM’s is that they neither recommend nor endorse aftermarket technologies; however, the use of these products does not automatically void the validity of the engine warranty.  If the cause is obviously unrelated to Dual Fuel, the OEM’s have historically honored the warranty and repaired the engine. This can be further strengthened by the fact that both Caterpillar and Cummins are now offering their own Dual Fuel kits for specific models of their generators.

Why can’t the Generator use 100% natural gas?

Because of the very High ignition temperature of natural gas (approximately 1300T), sufficient heat is not generated during the diesel compression stroke to ignite 100% natural gas. As such, dedicated gas engines employ spark plugs and an ignition system to facilitate combustion of the air-natural gas mixture. In contrast, during Dual Fuel operation, a reduced quantity of diesel fuel acts as the ignition source for the air-gas mixture; this process is often referred to as pilot ignition.

Will my engine lose power after conversion to Dual Fuel?

Under normal circumstances, engines converted to Dual Fuel do not suffer any horsepower/kW losses while operating in Dual Fuel Mode. Because the System maintains OEM compression ratio values and does not incorporate an air-throttling device, peak horsepower and efficiency levels of the converted engine remain on par with 100% diesel operation.

Will my engine run hotter on Dual Fuel?

The Dual Fuel technology has been designed to maintain OEM specifications for all engine temperatures including engine coolant temperature, oil temperature, and intake air temperature. The Dual Fuel System replaces diesel fuel normally consumed by the engine with an equivalent quantity of natural gas, relative to the heat value of each fuel. As such, engine air-fuel ratios during Dual Fuel operation remain largely equivalent to 100% diesel operation, resulting in normal peak exhaust gas temperatures and associated peak engine thermal loads.

What about efficiency?

The Dual Fuel System replaces diesel fuel with an equivalent quantity of natural gas. This process results in the same net fuel burn vs. load as would be experienced during 100% diesel operation. For each gallon of diesel fuel displaced during Dual Fuel operation, there is a corresponding consumption of approximately 140 cubic feet of pipeline quality natural gas (based on 129,000 btu/gallon # 2 diesel & 930 btu/scf natural gas).

Thus, for each gallon of diesel fuel displaced during Dual Fuel operation, an “equivalent gallon” of natural gas is consumed resulting in similar engine fuel efficiencies.

What effect will Bi-Fuel System have on the durability of my generator?

Generally speaking, operation in Dual Fuel mode has no negative effects on engine wear rates and durability. As explained above, because engine thermal loads are equivalent to 100% diesel operation, no excess wear of combustion chamber components (pistons, rings, valves, injectors, etc.) occurs. In addition, many users of Dual Fuel have reported positive benefits relative to engine wear including extended oil change intervals and extended time between overhauls. This is primarily the result of the cleaner burning characteristics of natural gas compared to diesel fuel.

What are the economic benefits to operating on Bi-Fuel?

Fuel cost savings resulting from operation in Dual Fuel mode will vary according to the respective cost of each of the fuels. If there is a significant cost differential between the cost of diesel fuel (per gallon, liter, etc.) and the equivalent quantity of natural gas (heat value basis) in favor of the natural gas, significant fuel cost savings would result. The closer the fuels are in price, the lower the fuel cost savings will be during Dual Fuel mode. In addition to fuel cost savings, engine maintenance savings (as explained above) may also contribute to the economic benefit of Dual Fuel operation.

Cummins Generators Dual Fuel Website
Caterpillar Dynamic Gas Blending