Project for Shell Petroleum Development Corp.

Warri, Nigeria

Project Description:

Convert a 500 kVa Caterpillar 3412 Diesel Standby Generator to Dual Fuel utilizing piped natural gas at SPDC Warri facility. Pilot Project to prove conceptual operation and potential for diesel cost [and environmental impact] reduction while utilizing flare gas for the existing diesel engine population supported by SPDC Nigeria


  1. Successful retrofit of Dual Fuel kit components carried out in two days of work while following Shell JHA and Work Site rules.
  2. Dual Fuel operation proved on second day. Generator run on Dual Fuel supply,under load.
  3. All systems confirmed normal operation.
  4. Dual fuel substitution result checked and verified by SPDC Conceptual ProjectsTeam, and Exclaim Technical Team on third, full day, of testing.


Because diesel engines are compression ignition engines, and lack spark plugs, to operate a diesel engine with an alternate combustible fuel source such as Natural gas as the main fuel diesel oil is used for the ignition of the gas/air mixture inside the cylinder (a portion of diesel oil is injected at the end of the compression stroke, thereby maintaining the original diesel operation principle).

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.

Common conversion features

  • Substantial savings on operation costs
  • Practically no engine modification required
  • Non-derated output power
  • Fuel flexibility: Possibility of bi-fuel or original pure diesel operations
  • Safe operations.
  • Lower emissions
  • Longer engine life span, longer service and maintenance intervals

Diesel/gas ratio:

It depends on the technical state of the engine, especially of the injection system. The typical Diesel / Gas ratio is 40/60% for the high-speed engines. If the operating output of the engine is constant and between 70-80% of nominal output, than it is possible to reach up to 30/70% ratio. If the operating output is lower (for example 50% of the nominal output) or if there are variations, the rate is about 45/55% (more of diesel is used). Generally, it is not possible to guarantee an exact diesel/gas ratio without a test being done after the conversion.