Due to reducing petroleum reserves' scarcity, the engineer has to consider alternative fuel sources for IC engines. Vegetable oils of the non-edible category can be used as a substitute fuel to diesel fuel and use gaseous fuel as a partial supplement to petrol fuel. Biogas technology offers a desirable direction to utilize certain categories of biomass for meeting partial energy needs. This study is to describe the production of biogas from cow dung in the fabricated floating drum type digester and was stored in the tube. Stored biogas was used as supplement fuel to run the single cylinder 305 cc variable speed engine under no load. The performance and emission characteristics of engines running on biogas and petrol blend were compared to petrol fuel operation. Results revealed that the performance of the engine was improved with the increases in the amount of gas substitution. Brake-specific fuel consumption was found to improve. However, emissions of HC and CO were increased with the increases in gas substitution, and reduced NOx emission was observed.
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Fossil fuels are non-renewable and require finite resources, which cause environmental pollution and high cost. Cheap and renewable resources are in great need. An efficient and feasible option is to depend on alternative fuel. Alternative fuels are obtained from waste other than petroleum sources. These can be produced domestically, reducing our dependence on fossil fuels. They produce less pollution than petrol or diesel. Alternative fuels can be used by slight modifications in the operating engine as an only fuel or as a supplementary fuel in dual fuel mode. Gaseous fuels are a good alternative in SI engines because they are easily miscible with air. Biogas is a good choice fuel and is obtained from cow dung, waste from poultry, plant, industrial and domestic is an easily available source of energy. Modern advancement in technology and biogas storage has to be made to use the fuel for IC engines. Hybrid engines that run biogas as supplementary fuel have a separate fuel storage system. The process is widely used in biogas production from animal waste using a digestion tank and anaerobic digestion. Anaerobic digestion is a microbial isolate from the digesters including Bacillus licheniformis, Escherichia coli and Clostridium, which are responsible for the breakdown of the complex substance. They observed the highest total gas yield (15.60 cm3) in the digesters which were left at ambient temperature and in which gas was collected over limewater. Research on biogas as a supplementary fuel which was used either in SI engines or CI engines is less exploded. To accomplish the research gaps this study has been performed to produce biogas from a simple mixture of cow dung and water in 3:1 proportion through anaerobic digestion. Bacteria present in cow dung help to break down complex substances resulting in a yield of biogas. It was stored temporarily and then tested on a single-cylinder petrol engine fuelled by biogas as a supplementary fuel along with petrol.
As conventional energy is to be depleted in near future, the development of renewable energy is very important for the variety of the energy supply. The global energy demand is produced from fossil resources. The depletion of fossil fuels and environmental pollution is the main focus of research into renewable energy mainly from waste organic resources. Alternate energy to fossil fuels is a challenge to improve security. Most countries are accepting the new promise for renewable energy supply and providing a possibility for sustainable evolution. Production of biogas from biomass is soured to reduce environmental pollution and provide extra revenue to the farmers (Amon et al., 2007). Biogas is produced from manure, plants, food wastes, offal, etc. through anaerobic fermentation under an anaerobic condition (absence of oxygen). Biogas from various sources like sewage, organic waste and landfills have a mixture of various quantities like CH4, CO2 and N2. Biogas from sewage contains CH4 54 - 64%, CO2 34- 44% and N2 is less than 1%. Biogas from organic waste, contains CH4 62- 72%, CO2 is 32- 42% and N2 is less than<1% while in landfills CH4 is 44- 55%, CO2 is 31- 42% and N2 is 3- 12%. Apart from these gases it also contains H2S and other sulphur siloxanes, aromatic and halogenated compounds (Amon et al., 2007; De aere, 2000; Rasi et al., 2007). The average calorific value of biogas is 6,0 kWh/m3 and depends on the methane percentage in the gas. From the safety point of view, the biogas ignition temperature is 700 °C and the stoichiometric air requirement for complete combustion is 5-7 m3 per m3 of biogas (Vindis et al., 2008; Lungkhimba et al. 2010). While biogas produces a temperature, pressure, and Solid/water ratio, pH value should be properly followed and maintained.