*2.3. WtE Process*

Waste can also be effectively treated in WtE facilities. Typically, large WtE plants thermally treat RES by incineration and the released heat is recovered using CHP production. According to [27], approximately 27% of all MSW generated in EU28 in 2014 was processed by incineration with energy recovery. In case of WtE, which is of the most importance in this paper, positive values of GWP are so-called GWP burdens, and they are the result of production of GHG and release of their emissions into the air.

On the other hand, negative values are GWP credits, and they characterise decrease in global production of GHG, thanks to the replacement of fossil fuels and primary raw materials. GWP calculation method for WtE plant is based on the work [15], where the author introduced inventory analysis. Here, GHG production is calculated similarly following the same assumptions and data.

To operate the WtE facility effectively and sustainably, it is essential to pay attention to a range of conditions—one of them is also the input waste composition. Table A1 in Appendix A lists the RES composition used in the calculations in this paper. Biowaste share for particular RES composition is relatively high (28.9%) when compared to other components. Waste composition significance and its effect on the efficiency and operating conditions of the plant was described in [15]. Biowaste is characterised by zero content of fossil-based carbon. Therefore, its incineration is free of GWP burdens and generates GWP credits as replacement of traditional fossil-based resources. On the other side, its calorific value is only 4.6 GJ.t<sup>−</sup>1, which is quite low when compared, e.g., with plastics.
