Energetic potential and environmental assessment of solid wastes as alternative fuel for cement plants

The main objective of this paper is to evaluate the energetic potential and the environmental impacts of different kinds of wastes derived from different sources, namely olive Kernels (OK), sewage sludge (SS), chicken residues (CR), animal meal (AM) and fluffy RDF (F-RDF) and to figure out their feasibility as alternative fuels for cement plants. Decisive parameters promoting the use of wastes as secondary fuels such as: Calorific value, moisture, volatile matter, ash, chlorine, sulfur contents and trace elements were determined. A brief comparison of these fuels has been summarized. A model of fossil fuel savings is estimated using different scenarios with several substitution rates. The results show that chicken residues, fluffy RDF and olive kernels have the highest caloric values, which are 25.02 MJ/kg, 24.79 MJ/kg and 21.68 MJ/kg respectively. Moreover, fluffy RDF can help mitigate carbon dioxide (CO2) emissions due to its lower carbon content than coal, and its similar caloric power. In addition to their favorable calorific values, chicken residues and olive kernels allow for a significant reduction of fossil-derived CO2 due to their biogenic origin. Generally nitrogen oxide (NOx), sulfur dioxide (SO2) emissions decrease while Co-firing waste with coal.