Experimental studies on Biogas Production and Its Utilization in a Direct Injection Diesel Engine Run on Dual Fuel Mode

Biodiesel is considered as one of the potential liquid alternative fuels in many countries in the world. It is produced from edible and non-edible oils, animal fat, and algae by the transesterification process. In India, Karanja (Pongamia pinnata) a non-edible oil seed is considered as a potential feedstock for biodiesel production. The de-oiled cakes of Karanja seed obtained from expeller units are of no use, and are disposed in the open. The disposal of such non edible oil cake in the open and land fill generates various anthropogenic gases, and may increase the global warming potential (GWP). The organic matters contained in these de-oiled cakes can be converted to useful energy by adopting a proper waste-to-energy conversion process. Hence, an attempt was made in this investigation to use the Karanja seed cake (SCK) as a potential feedstock for producing biogas by anaerobic digestion, and the produced biogas was proposed as an alternative fuel for CI engines. Initially, biogas was produced from four different proportions of SCK mixed with cattle dung (CD) in small scale rectors, to study the different parameters effecting the biogas production. The SCK-CD was mixed in the proportion of 75:25, 50:50, 25:75, and 0:100 in percentage on a mass basis, and the mixtures were denoted as S1, S2, S3, and S4 respectively. Important parameters, such as the pH, temperature, hydraulic retention time (HRT), and carbon/nitrogen ratio (C/N) were evaluated and analyzed. The results indicated that the sample S3 gave the best result, in comparison with the other samples, and the methane (CH4) and carbon dioxide (CO2) contents in the biogas were found to be about 73% and 17% respectively. The sample S3 was chosen for producing biogas in a large scale floating drum digester. The biogas obtained from the floating drum digester was stored in a gas bag and then characterized for its physiochemical properties, to ensure its application as a gaseous alternative fuel for CI engine