Energy, exergy, and exergoeconomic analyses of plastic waste-to-energy integrated gasification combined cycles with and without heat recovery at a gasifier

Abstract

Energy, exergy, and exergoeconomic analyses were performed for two plastic-integrated gasification combined cycle (plastic-IGCC) systems to evaluate the performance of the plastic waste-to-energy cycles. Plastic waste-to-energy is a promising plastic treatment method that can resolve both plastic waste and environmental issues. Thus, improving the efficiency and economy of plastic-IGCC has become crucial because energy is generated during plastic waste-to-energy treatment while treating waste. The difference between the two modeled cycles is the location of heat recovery from the high-temperature syngas. In Cases 1 and 2, heat from the syngas was recovered with a heat recovery steam generator and a gas heater, respectively, to increase the temperature of the air entering the gasifier. The maximum net efficiency for Case 2 increased by 8.2% (from 35.41% to 43.57%), unlike that of Case 1, without changing exergy destruction. To assess the economic value and market potential, the unit electricity cost was examined for the condition in which the highest efficiency was obtained. The unit exergoeconomic costs for Cases 1 and 2 were 0.141 and 0.108 $/kWh, respectively, which were within the range of those in other energy recovery combined cycles; in addition, using air heaters for heat recovery reduced costs. The use of the air heater for heat recovery benefited energy and economic aspects without significantly changing exergy destruction. These findings have important implications for understanding the impact of gasifier agent conditions and energy recovery methods on the optimum conditions for plastic-IGCC. This study aimed to provide insights into the optimal design and operation of plastic-IGCC systems, considering both energy and economic aspects.