| 1. |
- Jerome, Adeline, 1994, et al.
(author)
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Environmental sustainability of high voltage motors: do better efficiency and repair lead to improved environmental impact?
- 2022
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Conference paper (other academic/artistic)abstract
- Various circular economy (CE) strategies, for instance lifetime extension by repair or reuse, have been suggested to improve products’ environmental performance. The literature emphasises the need to better understand the consequences of those CE strategies with assessment tools such as life cycle assessment (LCA). From previous assessments, Böckin et al. (2020) identifies energy use reduction and use extension by maintenance, repair or remanufacturing as relevant CE strategies for durable and active products. However, this conclusion is based on assessments of small- and medium-size electronic products, leaving out more durable and more energy consuming bigger products. In this study, the implementation of two CE strategies, energy use reduction and use extension by repair, is explored for high voltage (HV) motors delivering 135GWh per year over at least 20 years. Electric motors are prominent active products, representing 50% of the electricity consumption in Europe. Even in small numbers, HV motors represent a significant share of this consumption due to their more intensive use and high output power. Two main HV motor technologies exist: induction motors (IM) and synchronous motors (SM), which are more energy efficient. Both are often used until failure, which frequently occurs in stator windings but could be repaired by rewinding at the expense of a slight decrease in efficiency. This study aims to compare the life-cycle environmental impact of the two motor technologies and to explore their lifetime extension by repair in comparison to their replacement. For each motor technology, a cradle-to-grave LCA is performed for global warming and mineral and metal resource depletion impact categories. The IM has an efficiency of 97.3%, the SM an efficiency of 98.3% and both are run 20 years. Results show that the impact of electricity consumption during use is dominant. Besides, the SM has a lower environmental impact than the IM. In term of resource depletion, SM manufacturing is more impactful but lower energy losses during use compensate for the difference. Repair is modelled with the production of a new stator winding and a decrease in efficiency of 0.7%. Three scenarios are compared. The IM is initially used for 20 years, and an additional 10 years of use is provided by either 1) replacing with an IM with the same efficiency, 2) replacing with the SM, or 3) repair by rewinding. LCA results show that the additional energy losses after repair in scenario 3 offset the gain from avoiding the production of a new motor compared to scenarios 1 and 2. This study shows that the long lifetime and high energy requirements of HV motors lead the energy efficiency to be an essential factor for the life-cycle environmental performance. Choosing and maintaining high energy efficiency is key in this situation, especially for lifetime extension strategies to be beneficial for the product environmental performance. Reference: Böckin et al. (2020), How product characteristics can guide measures for resource efficiency. Resources, Conservation and Recycling 154, 104582.
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| 2. |
- Jerome, Adeline, 1994, et al.
(author)
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Mapping and testing circular economy product-level indicators: A critical review
- 2022
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In: Resources, Conservation and Recycling. - : Elsevier BV. - 0921-3449 .- 1879-0658. ; 178
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Research review (peer-reviewed)abstract
- Numerous indicators have been suggested as tools for assessing progress towards the circular economy (CE). However, it is unclear what specifically is captured by CE indicators and few studies have tested them on real cases. This review addresses this gap by describing and comparing the resource-related effects captured by existing resource-based product-level indicators and suggesting recommendations for their use and further development. First, the flows and processes quantified by product-level indicators are mapped on a novel flowchart model, which can also be used to select and develop indicators. Second, the indicators are tested on seven real cases. Third, indicator and life cycle assessment (LCA) results are compared. A significant divergence of indicators’ scope is found, where most capture a limited part of the product system. Moreover, important aspects of the CE are not captured: no indicator accounts for resource use in the use phase and there is limited attention to lifetime extension strategies. Additional limitations are the difficulties to assess multiple use-cycles and that most indicators cannot capture absolute mass variations, thus neglecting mass reduction strategies. The testing reveals that using a set of single-focus indicators may be necessary to outline trade-offs. Multi-focus indicators are sometimes harder to analyse but provide a more comprehensive assessment. The testing also illustrates that indicator and LCA results are not necessarily aligned. The latter provides information on environmental impacts and can point to trade-offs between impact categories such as climate change, resource use and land use, indicating that CE indicators cannot easily replace LCA.
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| 3. |
- Jerome, Adeline, 1994, et al.
(author)
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Repair for high-voltage electric motors energy efficiency vs resource use?
- 2022
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Conference paper (other academic/artistic)abstract
- Electric motors in the industry represent 69% of the industrial electricity consumption in Europe. Even if few in number, high voltage (HV) motors represent a significant share of this consumption due to their more intensive use and high output power. Two main HV motor technologies exist: induction motors (IM) and synchronous motors (SM), of which the latter are more energy efficient. Improving energy efficiency as well as use extension by maintenance, repair or remanufacturing have been identified as relevant circular economy strategies for improving the environmental performance of such active and durable products. However, the assessments performed focus on small- and medium-size electronic products, leaving out bigger products that are more durable and more energy consuming such as HV motors. Those motors are often used until failure, which frequently occurs in stator windings, and which could be repaired by rewinding at the expense of a slight decrease in efficiency. However, other use extension strategies such as reuse and remanufacturing are hindered by the customization of HV motors to their specific use. Finding an appropriate set-up for a second use is difficult for such motors and it is therefore performed seldom. The aim of this study is to compare the life-cycle environmental impact of lifetime extension by repair for the two motor technologies in comparison to their replacement.
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| 4. |
- Jerome, Adeline, 1994
(author)
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Repair or replace? Guidance from indicators and life cycle assessment on circular economy strategies for energy-using products
- 2022
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Licentiate thesis (other academic/artistic)abstract
- Various circular economy (CE) strategies, such as use extension with repair or reuse, have been suggested as a means for addressing the increasing resource and environmental footprint of society. To identify effective CE strategies, companies or policy makers seek guidance from the evaluation of resource use and environmental impact of alternatives that introduce different CE strategies to product systems. CE indicators and life cycle assessment (LCA) have been used for that purpose. However, a clear description of the differences between these two assessment methods as well as of the aspects accounted for by CE indicators is still missing. Therefore, the aim of this licentiate thesis is to advance the description of CE indicators and LCA in order to provide recommendations for practitioners to select the appropriate assessment method for their specific assessment goal. To this end, LCA and CE indicators are compared by considering the type of results generated and the modelling specifications. Specific attention is given to the assessment of use extension of energy using products (EuP). This comparison builds on two studies: a review and analysis of CE indicators which identify the flows and processes that indicators account for and how indicators’ and LCA results differ, and an LCA of the repair of a long-lived and energy intensive product which identifies what aspects are important to consider in the assessment of this overlooked product category. The comparison shows that the two assessment methods provide different types of results. CE indicators inform on variations of resource use and especially on variations that are relative to other flows in the product system. LCA provides information on the environmental impacts and thus makes it possible to identify trade-offs between different types of environmental impacts. Besides, LCA allows a greater flexibility than CE indicators in capturing flows and processes but requires an extensive data collection. In comparison, CE indicators, and especially indicators focusing on one CE strategy at a time, have the advantage of being more time-efficient and of providing a detailed description of variations in resource use. For assessing the reuse or repair of EuP, CE indicators are more limited than LCA with regards to ensuring that important changes in resource use are not missed. No indicator accounts for resource use in the use phase, and thus for changes in energy efficiency by design or with repair and for resources in energy production and transmission. These have however been found to be key aspects in the environmental performance of the repair of an energy intensive EuP. Therefore, to decide on a repair or replacement, the selection of CE indicators and LCA as assessment methods depends on the type of impacts that a practitioner wants to base its decision on (e.g., environmental impact and/or resource use) and on the important modelling specifications for the product system (e.g., resources in energy production and transmission for the repair of an energy intensive EuP). Further research could focus on understanding the needs from practitioners in specific contexts to develop the practicability of these recommendations and on exploring other central modelling aspects for use extension such as the product’s lifetime.
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