Environmental impacts of waste-to-energy processes in mountainous areas: The case of an Alpine region

Despite the efforts made towards circularity approaches in waste management, waste-to-energy (WtE) processes still represent a key step because they allow recovering energy from waste, reducing the amount of waste residuals that require landfill disposal and reusing part of the residuals for specific purposes (e.g. in the construction sector). However, the direct (incineration) or indirect (gasification) combustion of waste generates relatively high emissions of several air pollutants, with different levels of toxicity. In specific situations, the presence of a waste combustion plant may be incompatible with the presence of population nearby, especially in areas where the dispersion of air pollutants is limited by the local morphology and/or by unfavourable meteorological conditions. In such contexts, an alternative option exists: the conversion of the syngas produced by waste gasification into commercial products or fuels. This alternative would guarantee a significant reduction of the impacts on the local air quality, and it is expected to increase the level of acceptability of the WtE sector by the population: the syngas would not be burned locally to generate energy, but it would be used to produce valuable products or replace traditional fuels with more sustainable alternatives. Thus, this paper aims at discussing the potential local impacts of traditional WtE plants and the opportunities related to alternative WtE approaches that may increase the level of sustainability of this sector. This paper will make a specific reference to mountainous regions, where the atmospheric dispersion of air pollutants may be negatively affected by the local morphology. To better illustrate the potential issues involved, some case studies located in an Alpine valley of Italy will be presented and discussed.