Energy recovery – Gasification, combustion or plasma? : Competitor or complement?

Sammanfattning: Abstract Energy recovery – Gasification, combustion or plasma? -          Competitor or complement? The Swedish waste-to-energy system has been developed during many years, and the facilities are well established within the waste management system. Even though the waste volume is significantly reduced by 70 – 80 %, the residues are quite challenging to manage due to high content of pollutants. The air emissions are quite low today, but since waste contains various kinds of contaminants, there is a high need for extensive flue gas cleaning, adding to the residue that must be handled. Today, the main part of residues from flue gas cleaning and fly ash from Swedish waste-to-energy facilities are transported to Langöya, Norway to be used for remedial purposes of an old limestone quarry. However, this option will probably be phased out sometime after the year 2023 – 2025 and other solutions must be considered such as e.g. gasification.   The Plagazi Company has a patented process, including gasification and subsequent production of hydrogen gas, that may be used as a vehicle fuel. Although gasification is a well-known technique, there is still a great distrust in using the method for waste treatment purposes. There is a conception that gasification facilities are high energy consumers, with low operational performance and high investment costs. The present thesis is part of the B.Sc. Programme in Energy Engineering at the University of Umeå. The main thesis objectives are:   Study and explain significant differences and similarities between waste incineration and gasification; Describe pros-and-cons regarding various methods to produce hydrogen gas; Describe different gasification techniques. In addition, the Plagazi-process is described; local plasma gasification with low environmental impact and a second step including production of hydrogen gas. The present study is based on a literature review and interviews with experts in the field. The report excludes biogas production in anaerobic digestion plants.   The present report has proven that there are significant differences between various gasification devices. When making investment decisions regarding gasification as a waste treatment option; fuel quality and utilization of the syngas must be considered. The method developed by Plagazi may be suitable in the Swedish waste management system to treat household waste and/or flue gas residues from the combustion plants, for production of hydrogen gas as a vehicle fuel. A full-scale facility in operation is needed to evaluate the Plagazi process with respect to cost efficiency and performance. The Plagazi concept should not be viewed as a competitor to the profitable waste incineration plants, more preferably as a complement.