Thermodynamic, economic, and environmental footprint assessments and optimization of an innovative biogas-driven heat integration network, producing power, cooling, and heating

This study introduces an innovative trigeneration process using biogas fuel. This process produces electricity, heating, and cooling by combining a biogas burner, helium Brayton closed cycle, absorption refrigeration cycle, and three different organic Rankine cycles. The process scheme in this study was designed using Aspen HYSYS software, focusing on thermodynamic and economic-environmental analysis. In this respect, two optimization processes were done using non-dominated sorting genetic algorithm-II optimization techniques. Under the base design case, the energy, exergy, and electrical efficiencies were found to be 66.29 %, 38.73 %, and 40.69 %, respectively. The environmental analysis revealed that, in multi-product mode, carbon dioxide footprint was 39.46 % lower when compared to single generation mode and 59.38 % lower in the case of a separate product system. From an economic point of view, the cost-effectiveness of the process could be demonstrated by estimating that the general costing rate was 494 $/hour and the cost of the exergy unit was 18.49 $/GJ. The first optimization scenario had exergy efficiency and cost of exergy unit as the objective functions, which eventually gave the best results at 17.309 $/GJ and 0.496, respectively. Considering the same in carbon dioxide footprint and exergy efficiency, the obtained optimum values of these scenarios are 0.154 and 0.509 kg/kWh, respectively.