THEORETICAL STUDY OF EMISSIONS FOR STATIONARY SPARK IGNITION ENGINES FUELLED WITH BIOGAS

摘要

Power generation by using gas fuelled engines is widely spread around the world, especially in remote areas with no electric power transport infrastructure. Combined heat and power generation increases overall efficiency and provides environmental as well as economical benefits. The use of fossil fuels results in emissions of toxic gases and the increase of green house gases like carbon dioxide in the Earth atmosphere. One way of reducing pollution levels is using biofuels with obvious environmental benefits. Biogas is CO_2 neutral as it is obtained from organic waste. Spark ignition engines can be fueled with biogas without major changes and conversion efficiency is very high when cogeneration is employed. This theoretical study presents a method of evaluating emissions reduction when biogas is used. Several operating strategies are investigated, with different air-fuel ratios for a stationary engine. CO_2, CO and NO_x emissions values are calculated and the effect of methane content in the fuel is evaluated. A reduction both of NO_x and CO emissions values is noticed as the biogas methane content decreases, while carbon dioxide emissions are lower for methane rich biogas.