A. Ramesh is a chair professor of mechanical engineering at the Indian Institute of Technology Madras. He has over 26 years of teaching, research and industrial experience and has over 130 research publications. His research interests include renewable fuels, gasoline direct injection, homogeneous charge compression ignition, engine management, new and innovative engine designs. He has undertaken several projects for leading automotive industries and government agencies. His development activities have resulted in devices for which patents have been obtained or applied.  J. Narayana Reddy obtained his M.S by research from the Indian Institute of Technology Madras. He then worked in M/s Mahindra and Mahindra before joining the engine R and D of M/s Ashok Leyland, which is a leading truck manufacturing company in India. He has published research papers in the area of alternate fuels and his interests include alternative fuels, engine emission control and engine design.


Biogas can be produced by anaerobic digestion of a variety of biomass along with simultaneous generation of fertilizer [1]. Thus it is a very viable fuel for rural decentralized power production using internal combustion engines. Biogas is normally used in dual fuel engines wherein a small amount of diesel or biodiesel can used as the ignition source [2-4]. This experimental work demonstrates that straight vegetable oil - biogas dual fuel combination with engine modifications can enable power production using completely renewable fuels that are locally available in rural areas with little or no post processing. Biogas the main fuel was inducted along with air in a diesel while a small amount of Jatropha oil was injected for ignition.

Experiments were conducted under different load conditions while the biogas to Jatropha oil ratio was changed to study its effect. Advancing the injection timing for compensating for the increased ignition delay of jatropha oil along with biogas induction and increasing the injection rate to enhance atomization of the highly viscous vegetable oil resulted in improvements (Fig.1). Thermal efficiency was enhanced; smoke and HC emissions were reduced. The low flame speed of biogas due to the high CO2 [5] was increased by intensifying the air swirl which elevated the combustion rate and further lowered HC emission (Fig.2 and 3). On the whole the biogas – Jatropha dual fuel mode of operation with simple engine modifications opens a new way to produce decentralized power from available renewable sources for rural areas. Detailed experimental results of performance, emissions like HC, CO, NO, smoke and combustion parameters like heat release rate and rate of pressure rise will be presented and discussed in the paper. Comparisons of the experimental results will be made with the conventional biogas – diesel dual fuel mode.