The objective of this work is to review state of art practices and potential in diesel engines using greener fuels. Biogas with jatropha bio-diesel as ignition source was tested in a compression ignition diesel engine at six different loads under dual fuel mode. With a simple modification, the base engine was qualified to a dual fuel operation. For all the loads evaluated, dual fuel mode achieved a possible bio-diesel substitution of about 65%. In addition, it consumed lesser friction power as compared to the diesel mode during the operation. There were reductions in thermal efficiency, cylinder peak pressure and combustion noise under the dual fuel operation than the diesel mode due to lower burning velocity of biogas together with a longer pilot delay. However, this operation registered extremely lower NO x levels at all loads along-with reduced CO emissions at medium and higher loads. While significant increases in hydrocarbon emissions were observed. © (2012) Trans Tech Publications, Switzerland.