Internal Combustion Engine Fueled with Biogas: Energetic, Economic and Environmental Analyses

This article presents the use of internal combustion engines operating with biogas for electric power generation as an alternative to meet electrical demands in rural regions where the availability of this BioSource is greater. Two configurations with that engine are studied in this paper, the first one considers only electricity generation while the second one consists of a cogeneration system. This study contributes to comprehending biogas utilization as fuel and its combustion emissions gases impact, whereas technical aspects of internal combustion engine are analyzed in terms of energy balance and economics parameters. A locally manufactured generator group which operates with biogas as fuel is analyzed in terms of energy, economics, and the ecological aspects. In the technical analysis, the first law of thermodynamics is used to assess the power plant. On the other hand, the economic analysis, made with the calculation of electricity production cost, shows that the selected set is attractive and presents a low payback period of investment, less than three years. Results also show that, when the generator group is used in cogeneration mode, the payback is even lower. A sensibility analysis is performed varying the cost of biogas fuel and its influence on investment payback. Finally, from the environmental analysis, it is observed that the system has a low pollution indicator of 0.11 kgCO2e/MJ, which considers the equivalent emissions of carbon dioxide, resulting in an ecological efficiency in relation to electricity generation of 82%; in the case of a cogeneration system, this efficiency is increased to 93%.