Thermodynamic optimization and thermoeconomic evaluation of Afyon biogas plant assisted by organic rankine cycle for waste heat recovery

Abstract

The use of biomass in energy conversions is important for a renewable and sustainable energy future. Compared to other renewable energy sources, biomass is one of the important advantages of being stored and used in times of need and providing environmental benefits by recycling wastes. In this study, an integrated Organic Rankine Cycle (ORC) is performed to recover the waste heat of exhaust gases in the Afyon Biogas Power Plant, which produces biogas from chicken manure. Thermodynamic and thermoeconomic analyses and optimization of the waste heat recovery system integrated into the power plant are investigated. The energy and exergy efficiencies of the biogas power plant, which currently has a net power of 4000 kW, are calculated as 31.4% and 27.0%. As a result of the analysis, integrating the waste heat recovery system into the power plant increases biogas' net power production. The waste heat recovery to the power plant greatly improves the system's performance parameters and economic cost savings values. The maximum power capacity of the plant assisted by an Organic Rankine Cycle is calculated as 4828.8 kW. With the operation of the power plant under optimum operating conditions, the energy and exergy efficiencies are calculated as 37.4% and 32.1%, respectively. The optimum unit cost of the electricity produced from the plant through this energy recovery is calculated as 0.0376 $/kWh.