Energy recovery from waste gasification

Coal used in power stations has the potential to be partly replaced by fuels derived from pre-treated plastics and paper waste, reducing both dependency on fossil fuels and reliance on landfill. APME reports on a project in the Netherlands which it co-sponsored to develop a substitute fuel from plastics. The environmental assessment of the project compared the environmental impacts of coal substitution with other plastics recovery methods, including gasification in feedstock recycling and energy recovery from plastics waste in cement kilns. The study also compared coal substitution with the generation of power from burning biomass. 

The most suitable processes for the energy recovery from polyolefin wastes are (1) direct incineration, and (2) thermal and mechanical treatments. The latter procedures are applied for the production of gaseous, liquid, or solid fuels in a complex pyrolysis-gasification-incineration system. 

Gasification and pyrolysis are the thermal conversion processes available for the thermal treatment of solid wastes. As shown in Figure 8.3, different by-products are produced from the application of these processes and different energy and matter recovery systems can be used to treat these products [16, 27]. Both pyrolysis and gasification produce three different phases a solid phase (char, 5-25 wt%), liquid phase (tars, 10-45 wt%) and gas phase [14, 22, 28]. The main disadvantages of plastic pyrolysis and gasification are the necessity to control the chloride content in the feedstock and the risk of bad fluidisation because of particle agglomeration [29]. 

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