A comprehensive experimental study of municipal solid waste (MSW) as solid biofuel and as composite solid fuel in blends with lignite: quality characteristics, environmental impact, modeling, and energy cover

Abstract

Recently, coal power plants across Europe have been reopened. Alternative fuels are needed for energy autonomy purposes, for a smoother transition to the post-lignite era and for sustainable development. In this work, different categories of municipal solid wastes (MSW) and their blends with lignite were studied for their potential use as alternative fuels. Seventeen samples were studied using several techniques: gross calorific value (GCV), proximate analysis, ultimate analysis, ion chromatography, ash elemental analysis, thermogravimetric analysis, kinetic modeling and thermodynamic analysis. A determination of empirical chemical formulas was performed. Slagging/fouling potential was evaluated with various indices including modified indices that take into account ash production and GCV. Maximum emission factors were calculated and defined per produced MJ. Also, an environmental footprint index was developed regarding the environmental impact of solid wastes. The GCV experimental results were compared with those of twenty different empirical models. Moreover, several case studies were performed to evaluate the potential of covering the energy demands, with combustion of MSW, in Greece and Europe. The results showed that MSW as a primary/secondary fuel is an attractive solution considering the fact that it boasts better characteristics in comparison with lignite. Moreover, the environmental footprint index (EFIsw) of the MSW revealed a much smaller environmental impact. The high N content is not always translated to high emissions if NO is expressed per produced MJ (gNO/MJ). In addition, MSW can also be used as a significant contributor in covering energy demands regarding the energy recovery potential.Graphical abstract