Design and optimization of multigeneration biogas power plant using waste heat recovery System: A case study with Energy, Exergy, and thermoeconomic approach of Power, cooling and heating

This study modeled and analyzed transforming an operational biogas power plant into a trigeneration system with power, cooling, and heating. In this context, the energy, exergy, and optimum unit energy costs of this trigeneration system's power, cooling, and heating are investigated. The transformation of the clean energy potential of Afyonkarahisar city as biogas into power is investigated and analyzed by realizing it on an established biogas power plant. The high-temperature exhaust gases from the power unit (PU) are directed to the generator of an absorption cooling system, operating the cooling unit (CU). Exhaust gases from the generator, which are still hot, start a heating unit (HU) for space heating and are released into the atmosphere. As a result of the optimization, The energy efficiency, exergy efficiency, fuel consumption, and unit electricity cost of the existing power plant are 39.54%, 34.65%, 0.3161 kg/s, and 0.042 $/kWh. By integrating the optimized cooling unit to power unit, energy efficiency, exergy efficiency, and unit cooling cost of the plant were 54.2%, 43.39%, and 0.0352 $/kWh. Finally, with the integration of the heating unit to the plant, energy efficiency, exergy efficiency, and unit heating cost of the plant were 74.2%, 50.14%, and 0.0178 $/kWh, respectively.