1,721,362 research outputs found
Life cycle assessment of multi-loop recycling: Opportunities and Challenges
Full text linkToday, circular economy plays a prominent role in optimization of natural resource consumption, while also minimizing waste generation throughout the life cycle of a product. Both in relation to climate targets, the UN Sustainability Development Goals, as well as simply meeting recycling targets at national level. Keeping products, materials and resources in subsequent production cycles, for as long as possible, is one of the fundamental concepts of circular economy, and consistent strategies for how to improve resource utilization throughout the life cycle(s) of products are needed. Regarding the end-of-life waste stage of the product cycle, this can be achieved by reusing, repairing and recycling waste materials. However, within waste management most focus has been simply on recycling with little reflection of the material loops in a longer time perspective. Therefore, to avoid implementation of circular economy initiatives that may lead to net environmental impacts rather than benefits, comprehensive and systemic assessments are needed also involving subsequent recycling loops. While life cycle assessment (LCA) of repairing, reuse, recycling, and utilization options have been provided in literature, little attention has been placed on cascading and multiple recycling loops, although this is one of the primary intentions behind circular economy.
This study provides preliminary results evaluating LCA approaches from the perspective of multi-loop and cascading recycling with the aim of identifying opportunities, limitations and challenges based on current literature. Recommendations are provided based on evaluation of simple cases
Challenges of Implementing New Technologies in Future Waste Management - Example of Chemical Recycling
Full text linkCircular economy plays a prominent role in the transition of Europe towards a more sustainable society. To achieve its ambitious targets for waste, the EU will most likely have to explore new technological pathways. The ongoing transition towards circular economy has induced more ambiguity in waste management due to many new suggestions for how individual waste fractions should be managed and processed. Over the past years, there has been an ongoing debate about the potential environmental benefits of introducing new technologies into the sector, the integration of these technologies within the waste management system, and the implementation roadmap for new technologies. Plastic waste represent one of the more complex material fractions for which recycling can be achieved in different ways. One of technologies that has received a lot of attention is chemical recycling. It is often seen as an attractive supplement to mechanical recycling potentially resulting in recycled material of higher quality and thereby contributing to circular economy targets. On the other hand, implementation of a new technology, and chemical recycling is no exception here, is often limited by several challenges: What are the challenges of implementing new technologies in future waste management with focus on increased resource recovery and recycling? How can chemical recycling technologies best support the transition towards circular economy and to which extent should chemical recycling be prioritized over mechanical recycling? The presentation will address strategic technology implementation with chemical recycling as an illustrative case in the perspective of potential: i) technology performance and configurations, ii) strategic implementation scenarios, and iii) roles of new technologies in a changing waste management system
Environmental assessment framework for bio-based methane production via anaerobic digestion, gasification, and gas upgrading
Full text linkIn the endeavor of supporting the transition towards a low fossil carbon energy sector, it is necessary to exploit the potentials of waste and bioresources available within a country or region. It is important to combine the best ways of energy conversion based on physico-chemical properties of waste and bioresources, and technology conversion pathways, in vision of the energy supply-demand and environmental targets. While replacement of natural gas with bio-based methane from waste and bioresources is a promising solution, several challenges may exist: i) the local availability of waste and bioresources, ii) their physico-chemical heterogeneity, which may affect the technological performance of bio-based methane production, iii) the consequences of diverting waste and bioresources from their current uses, iv) the fulfillment of regional gas demands, and v) the need for systemic environmental benefits associated with the changes.
With this study, we provide an environmental assessment framework supporting decisions at regional and national scales associated with production of methane from waste and bioresources for use in local gas grid infrastructures. While the assessment framework may be applicable for a variety of gas supply-demand situations, we implemented it on a French region, Occitania (72,700 km2, 5.8 M inhabitants), with concrete ambitions of local energy transitions and climate savings. The three selected technology conversion pathways were: i) anaerobic digestion with hydrogen upgrading, ii) anaerobic digestion with water scrubbing upgrading, and iii) gasification with C-to-CH4 upgrading. The environmental performance was evaluated through a process-oriented life cycle assessment (LCA) with results interpretations at two levels: technology level (tier 1), and system level (tier 2). In tier 1 results, the three conversion pathways were evaluated individually relative to the production of 1 Nm3 of bio-based methane with given characteristics of injection and network distribution. Here, we quantified and identified the environmental benefits, the process hotspots, and the technology-by-technology comparison. While, in tier 2 results, we evaluated combinations of waste and bioresources with technology conversion pathways reflecting the supply of methane demand and overall climate change impacts.
The results showed that Occitania has the potential for fulfilling and exceeding the annual gas demand of 17.5 TWh, seeing export of bio-based methane as a further possible strategy in vision of promoting local bioeconomy. In addition, for manure, green waste, and sludge, the production of bio-based methane in anaerobic digestion resulted in more climate benefits than their current uses. Gasification was found as a promising technology for bio-based methane production, generating about five times more methane than anaerobic digestion for some bioresourc
System Level Life Cycle Assessment Models for EU and National Waste Management
Full text linkGlobal production and consumption has increased dramatically in recent decades and waste is currently being generated faster than any other environmental pollutant (Hoornweg et al., 2013). This has led world leaders to embrace the concept of a circular economy, where the ‘end-of-life’ concept is replaced with ‘restoration’ (Ellen MacArthur Foundation, 2020). The EU has thus, established a range of regulatory targets that prioritize the recycling and reuse of resources over incineration and landfill (European Commission, ND). This will inevitably lead to a wide range of new technological developments and product design requirements etc., to accommodate these targets. However, if waste is mismanaged, it can have detrimental consequences on both human health and the environment (Taelman et al., 2018). Thus, it is imperative that the impacts of waste management systems are assessed to ensure resource circularity whilst avoiding any adverse effects. In addition, it is important to assess whether or not the regulatory targets are aimed at the appropriate waste streams and sectors. Currently, no studies provide a comprehensive and system level life cycle assessment (LCA) model that enables consistent assessment of all of the waste streams occurring at national or regional level. This study, therefore, contributes to an ongoing EU project that seeks to develop a flexible modelling framework, which is adaptable to changes in framework conditions, technology options and regulatory focus etc., for quantification of relevant impacts on the EU waste management system, with particular focus on addressing future changes, tracking material flows, uncertainty analysis, and on import of EU and country-specific waste data through Eurostat. At the conference, the current model set-up along with any preliminary results and ongoing recommendations are presented. References Hoornweg, D., Bhada-Tata, P., and Kennedy, C. (2013). Environment: Waste Production Must Peak This Century. Nature, v. 502, pages 615-617. https://doi.org/10.1038/502615a. Ellen MacArthur Foundation (2020). ‘It’s time to step up, not step back’ – more than 50 global leaders pledge to build back better with the circular economy. Retrieved from: https://www.ellenmacarthurfoundation.org/news/more-than-50-global-leaders-pledge-to-build-back-better-withthe- circular-economy. European Commission (ND). Waste and Recycling. Retreived from: https://ec.europa.eu/environment/topics/waste-and-recycling_en. Taelman, S. E., Tonini, D., Wandl, A., Dewulf, J. (2018). A Holistic Sustainability Framework for Waste Management in European Cities: Concept Development. Sustainability, 10(7), 1 33. https://doi.org/10.3390/su1007218
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Energy recovery from plastic and biomass waste by means of fluidized bed gasification: A life cycle inventory model
No full textThe study provides for the first time a life cycle inventory model for the fluidized bed gasification of wastes, based on a large amount of high-quality data. All of them have been obtained from a pilot scale fluidized bed gasifier, fed with ten types of waste and biomass, under a wide range of operating conditions. The model refers to commercial scale gasifiers having a “thermal configuration”, where the generated syngas is immediately burned downstream of the reactor. Key relationships between process- and waste-specific parameters have been defined. The model quantifies the main inputs and outputs of the gasification process (emissions, energy recovery, ash disposal, resource consumptions), providing high-quality data that could contribute to improve life cycle assessment modelling of waste gasification. Finally, some case studies have been implemented in the EASETECH software to illustrate the model applicability, evaluate the role of main parameters, and compare the environmental performances of gasification power units with that of the European electricity mix. The performances appear highly affected by metal contents in the waste-derived fuels, while the model results to a limited extent are sensitive to the equivalence ratio and the net electrical efficiency of the energy conversion
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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