Performance analysis and modeling of energy from waste combined cycles

Municipal solid waste (MSW) is produced in a substantial amount with minimal fluctuations throughout the year. The analysis of carbon neutrality of MSW on a life cycle basis shows that MSW is about 67% carbon-neutral, suggesting that only 33% of the CO2 emissions from incinerating MSW are of fossil origin. The waste constitutes a “renewable biofuel” energy resource and energy from waste (EfW) can result in a net reduction in CO2 emissions. In this paper, we explore an approach to extracting energy from MSW efficiently – EfW/gas turbine hybrid combined cycles. This approach innovates by delivering better performance with respect to energy efficiency and CO2 mitigation. In the combined cycles, the topping cycle consists of a gas turbine, while the bottoming cycle is a steam cycle where the low quality fuel – waste is utilized. This paper assesses the viability of the hybrid combined cycles and analyses their thermodynamic advantages with the help of computer simulations. It was shown that the combined cycles could offer significantly higher energy conversion efficiency and a practical solution to handling MSW. Also, the potential for a net reduction in CO2 emissions resulting from the hybrid combined cycles was evaluated.