Eco-friendly energy generation model of a tri-generation system using renewable biogas fuel, Brayton cycle, and Rankine cycles for sustainable electricity, heating, and cooling production

In this study, a new tri-generation process using biogas fuel is presented with the aim of generating electricity, heating, and cooling. The system is designed by integrating a biogas burner, a CO2 Brayton cycle, an absorption refrigeration cycle, and two organic Rankine cycle (ORC) subsystems. A complete assessment of the system performance has been done on energy, exergy, economic, and environmental grounds, offering a full insight into its ability to perform. The energy and exergy analysis indicate that the system has a total energy efficiency of 73.47 %, an exergy efficiency of 32.54 %, and an electrical efficiency of 32.27 %, indicating its capability to effectively convert biogas fuel into various forms of useful energy. Environmentally, the system offers an additional advantage in that it has net CO2 emissions of 2711 kg/h, a 57.45 % decrease compared to the traditional single-generation methods. From a financial perspective, the system carries an annualized cost of $9,877,852 and a satisfactory levelized energy cost of 0.112 USD/kWh, making it a competitive choice in energy markets. Furthermore, the return on investment evaluation shows that the system with a payback period of 4.22 years shows a relatively quick recovery of the initial capital, making the project more desirable from an investment standpoint. To further enhance system performance, the multi-dimensional optimization was conducted in which the optimal conditions resulted in exergy efficiency of 34.04 %, levelized energy cost of 0.10 $/kWh and carbon footprint of 0.27 kg/kWh.