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This work presents the most important aspects that should be considered for assessing new marine litter reduction and processing technologies. The most relevant technology features are highlighted using a Delphi method capable of gathering and handling a large quantity of valuable data in areas where information is lacking. This relies on judgements provided by recognized experts in a particular area of knowledge, through an organized procedure based on a structured questionnaire and its reiterations. The Delphi process developed in this study completed two rounds. In the first round, a questionnaire with 55 statements (potentially important aspects) was shared with experts and stakeholders from different types of institutions (Administrations, Marinas and Ports; Associations; Companies; Universities; and Research Centers). Appropriate statistical analysis of the responses determined the degree of consensus and the level of importance perceived for each aspect. Feedback information based on analysis of the answers provided during the first round was included in a second round of the survey that focused on the statements that did not gather enough consensus, and therefore needed to be reevaluated by the expert group. After checking the stability of the results between rounds, the conclusions are set out and a list of the aspects to be considered in different decision-making contexts is drawn (from technology development, investment to marketing and policy making) taking into account technical, environmental, socio-economic, and political issues.

This paper is a systematic review of studies that used multicriteria decision analysis (MCDA) to address plastic waste management. A literature search for scientific articles in online databases (Web of Science and Scopus) enabled us to identify 20 relevant papers from 2008 to 2021, spanning case studies in three continents. These studies focus on: plastics as a resource (material), plastics as a product (reverse logistics), and plastics as a problem (pollution). Content analysis methodology was used, with the focus being on how the authors used MCDA for managing plastic waste, which has relevance for researchers and practitioners. Alternative solutions were found for the selection of disposal methods for almost all types of plastic categorized in this review. The most popular method was AHP, followed by TOPSIS, outranking methods, MAUT/MAVT and simple weighted sums, with some studies including more than one method. The choice of criteria spanned operational (mostly), but also environmental and economic aspects to evaluate the alternatives. Less frequently, one finds criteria related to social, managerial, and political aspects. The weighting of the criteria was performed mainly by consulting experts, followed by decision makers. Representatives of the affected population or other stakeholders have been consulted only on a few occasions. The authors of the studies consider their application of MCDA was successful, highlighting mainly the importance of being able to encompass different dimensions in the evaluation of the alternatives and the transparency of the process. In most cases, a winning alternative emerged clearly, which sometimes was a combination of multiple strategies. We also report other recommendations of these authors concerning marine and terrestrial plastic waste management.

Many decision problems manage linguistic information assessed through several ordered qualitative scales. In these contexts, the main problem arising is how to aggregate this qualitative information. In this paper, we present a multi-criteria decision-making procedure that ranks a set of alternatives assessed by means of a specific ordered qualitative scale for each criterion. These ordered qualitative scales can be non-uniform and be formed by a different number of linguistic terms. The proposed procedure follows an ordinal approach by means of the notion of ordinal proximity measure that assigns an ordinal degree of proximity to each pair of linguistic terms of the qualitative scales. To manage the ordinal degree of proximity from different ordered qualitative scales, we provide a homogenization process. We also introduce a stochastic approach to assess the robustness of the conclusions.

Moving towards a global bioeconomy can mitigate climate change and the depletion of fossil fuels. Within this context, this work applies a set of multi-criteria decision analysis (MCDA) tools to prioritise the selection of five alternative bioenergy systems for residential heating based on the combination of three commercial technologies (pellet, wood stove and traditional fireplace) and two different feedstocks (eucalypt and maritime pine species). Several combinations of MCDA methods and weighting approaches were compared to assess how much results can differ. Eight indicators were used for a sustainability assessment of the alternatives while four MCDA methods were applied for the prioritisation: Weighted Sum Method (WSM), Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS), Elimination and Choice Expressing Reality (ELECTRE), and Preference Ranking Organization Method for Enrichment Evaluation (PROMETHEE). Regarding the sustainability performance indicators, the highest environmental impacts were calculated for the fireplace alternatives, and there was not a best environmental option. Also, no clear trend was found for the economic and social dimensions. The application of MCDA tools shows that wood stove alternatives have the best sustainability performance, in particular wood stove with combustion of maritime pine logs (highest scores in the ranking). Regarding the worst alternative, fireplaces with combustion of eucalypt logs ranked last in all MCDA rankings. Finally, a sensitivity analysis for the weighting of the performance indicators confirmed wood stoves with combustion of maritime pine logs as the leading alternative and the key role of the analysts within this type of MCDA studies.

The significant energy consumed by road transportation and the difficult market penetration of Alternative Fuel Vehicles (AFVs) has led to a substantial body of research aiming to understand consumer preferences and future demand for AFVs. The individual characteristics of consumers are one of the explanatory factors of these preferences. In this context, the main purpose of this work is to present a comprehensive state-of-the-art review of how consumer demographics influence their preferences concerning AFVs. This review focuses on papers that applied Choice Modelling techniques to elicit individual consumer preferences for AFVs through stated preference surveys. Age, gender, income, level of education, family size, driving habits and number of vehicles per household were selected for analysis. This study also adds to the literature by analyzing the influence of demographic characteristics on preferences of Portuguese consumers. Very few studies addressed the influence of demographics on preferences for vehicle attributes. Considering the influence of consumers’ income and age, no consistent results were found. However, when age and consumers’ nationality were crossed, a potential trend of consumers’ age influence was unveiled. Regarding gender, level of education and family size, it was observed that consumers with higher education levels, women and consumers with larger families have higher preferences for AFVs.