Life cycle assessment of a micro-region Hungarian municipal solid waste: Evaluation of six waste-to-energy scenarios

Waste-to-energy technologies are key to a sustainable future. The non-recyclable share is often converted to refuse-derived fuel (RDF) for energy utilization to landfill only about 10% of the initial volume. The composition of such fuels may significantly vary; therefore, the currently investigated samples were compared to several others available in the literature and found to be internationally representative. Then six different waste-to energy scenarios were evaluated, suitable for a Hungarian micro-region: steam turbine, external combustion gas turbine, Organic Rankine Cycle with both direct and indirect fuel use, gas turbine, and internal combustion engine. The first three incinerated RDF, while the last three utilized pyrolysis gas of RDF. The thermal cycle of all six scenarios was evaluated first, followed by their assessment of the energy efficiency factor of the recovery, R1, mandated by the European Parliament and of the Council in Annex II of Directive 2008/98/EC on waste. It was concluded that the R1 threshold of 0.65 was only fulfilled by the gas turbine and the internal combustion engine. Finally, the environmental impact of the systems is addressed via life cycle assessment. The results were normalized and weighted to end up with a single score to facilitate decision-making, which is a novel approach in the field of WtE system assessment. The steam turbine, the gas turbine, and the internal combustion engine were all relatively efficient thermal cycles, resulting in a very similar positive impact with a mean of 321 person equivalent. This measure of the two Organic Rankine Cycle scenarios and the external combustion gas turbine was 639 person equivalent.