Energy from waste/gas turbine hybrid combined cycles and their potential for GHG emissions reduction

Municipal solid waste (MSW) is produced in a substantial amount with minimal fluctuations throughout the year. The analysis of carbon neutrality of MSW on life cycle basis shows that about 33% of the total CO₂ emissions from incineration of the waste are of fossil origin, which implies that MSW is 67% carbon-neutral. The waste constitutes a "renewable biofuel" energy resource and energy from waste (EfW) can result in net CO₂ emissions reduction. In this paper, we explore an exciting 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 or air cycle where the low quality fuel-waste is utilized. This paper assesses the viability of EfW/gas turbine 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 efficiency of energy conversion and practical solutions to handling the waste. Also, the potential for net CO₂ emissions reduction resulting from the hybrid combined cycles was evaluated.