Performance of Various Fuels: Gasoline, Liquefied Petroleum Gas and Biogas from Agricultural Biomass Waste in a Two-Stroke Internal Combustion Engine

The Philippines is an agricultural country with massive agricultural waste. The Biofuels Law (Republic Act 9367) aims to minimize the dependence on fossil fuels and encouraged the use of bio-based fuel sources as an alternative fuel in rural areas where farming is the only source of income, and energy is scarce. Biogas is a renewable energy carrier consisting of methane and carbon dioxide mixture. Because of its improved mixing ability with air, clean-burning nature and high-octane number that resists knocking, biogas is an excellent alternative source of energy for internal combustion engines. The single-cylinder two-stroke spark-ignition (43 cm3) was designed to be fed with a variety of fuel in order to assess engine performance parameters such as brake power, brake speed, brake-specific fuel consumption (BSFC) and thermal efficiency at different throttling positions (low- and high-load throttle). This study evaluated the engine performance of biogas (cow, swine and cow-swine manure), liquefied petroleum gas (LPG) and gasoline with two-stroke engine oil (2T) in a dynamometer without modifying the compression ratio. To optimize its use as a fuel for power generation, biogas was purified using hydrogen sulfide adsorption and carbon dioxide absorption. The results showed that biogas fuel from swine manure generated the highest electrical power load of 761 W with a methane concentration of 51% and a BSFC of 1.4 kg/kW-h. The LPG achieved the highest engine speed at 14,700 rpm with 549 W. In conclusion, the purified biogas fuel can be used in a small-scale internal combustion engine.