Environmental sustainability assessment in the process industry: A case study of waste-to-energy plants in Spain

• A methodology to assess the environmental performance of processes was developed.
• Life cycle thinking methodology is based on resources and environmental burdens.
• The methodology allows to obtain a single index to help the decision making process.
• As a case study several waste to energy plants in Spain were analysed.
• The plants showed worse air and water burdens, and a lower land impact than Spain.

This study proposes a technical procedure based on a life cycle approach for implementation of the environmental sustainability assessment (ESA) of several waste-to-energy (WtE) plants located in Spain. This methodology uses two main variables: the natural resources sustainability (NRS) and the environmental burdens sustainability (EBS). NRS includes the consumption of energy, materials, and water, whereas EBS considers five burdens to air, five burdens to water, and two burdens to land. To reduce the complexity of ESA, all variables were normalised and weighted using the threshold values proposed in the European Pollutant Release and Transfer Register regulation. The results showed the plants studied had a greater consumption of natural resources than Spain, ranging from 1.1 to 2.0 times higher than the Spanish reference consumption. The comparison of Spain with the BREF reference on waste incineration showed that only in the variable related to materials, did Spain have a lower consumption (1.80 times lower). In terms of EBS, air and land impacts were the highest contributors to global burden. The WtE plants presented higher burdens to air and water than Spain, whereas only one plant exceeded the average burden to land of Spain. Finally, this paper demonstrated the usefulness of the ESA methodology to reduce the complexity of LCA and assist the decision-making process in choosing the best option from an environmental point of view. This procedure can be used to obtain an overview of the environmental performance of WtE plants, as well as to assess individual burdens and thereby determine the main environmental hotspots, thereby improving the critical points of the process.