Summary
The fear that human consumption is causing climate change, biodiversity loss, and mineral scarcity has recently prompted interest in reuse because of the intuitive belief that it reduces new ...production and waste. The environmental impacts of reuse have, however, received little attention—the benefits typically assumed rather than understood—and consequently the overall effects remain unclear. In this article, we structure the current work on the topic, reviewing the potential benefits and pitfalls described in the literature and providing a framework for future research.
Many products’ use‐phase energy requirements are decreasing. The relative importance of the embodied impacts from initial production is therefore growing and the prominence of reuse as an abatement strategy is likely to increase in the future. Many examples are found in the literature of beneficial reuse of standardized, unpowered products and components, and repairing an item is always found to be less energy intensive than new production. However, reusing a product does not guarantee an environmental benefit. Attention must be paid to restoring and upgrading old product efficiencies, minimizing overspecification in the new application, and considering whether more efficient, new products exist that would be more suitable. Cheap, reused goods can allow many consumers access to products they would otherwise have been unable to afford. Though socially valuable, these sales, which may help minimize landfill in the short term, can represent additional consumption rather than a net environmental benefit compared to the status quo.
Summary
Additive manufacturing (AM) proposes a novel paradigm for engineering design and manufacturing, which has profound economic, environmental, and security implications. The design freedom ...offered by this category of manufacturing processes and its ability to locally print almost each designable object will have important repercussions across society. While AM applications are progressing from rapid prototyping to the production of end‐use products, the environmental dimensions and related impacts of these evolving manufacturing processes have yet to be extensively examined. Only limited quantitative data are available on how AM manufactured products compare to conventionally manufactured ones in terms of energy and material consumption, transportation costs, pollution and waste, health and safety issues, as well as other environmental impacts over their full lifetime. Reported research indicates that the specific energy of current AM systems is 1 to 2 orders of magnitude higher compared to that of conventional manufacturing processes. However, only part of the AM process taxonomy is yet documented in terms of its environmental performance, and most life cycle inventory (LCI) efforts mainly focus on energy consumption. From an environmental perspective, AM manufactured parts can be beneficial for very small batches, or in cases where AM‐based redesigns offer substantial functional advantages during the product use phase (e.g., lightweight part designs and part remanufacturing). Important pending research questions include the LCI of AM feedstock production, supply‐chain consequences, and health and safety issues relating to AM.
Material efficiency: A white paper Allwood, Julian M.; Ashby, Michael F.; Gutowski, Timothy G. ...
Resources, conservation and recycling,
January 2011, 2011, 2011-01-00, 20110101, Letnik:
55, Številka:
3
Journal Article
Recenzirano
For most materials used to provide buildings, infrastructure, equipment and products, global stocks are still sufficient to meet anticipated demand, but the environmental impacts of materials ...production and processing, particularly those related to energy, are rapidly becoming critical. These impacts can be ameliorated to some extent by the ongoing pursuit of efficiencies within existing processes, but demand is anticipated to double in the next 40 years, and this will lead to an unacceptable increase in overall impacts unless the total requirement for material production and processing is reduced. This is the goal of material efficiency, and this paper aims to stimulate interest in the area. Four major strategies for reducing material demand through material efficiency are discussed: longer-lasting products; modularisation and remanufacturing; component re-use; designing products with less material. In industrialised nations, these strategies have had little attention, because of economic, regulatory and social barriers, which are each examined. However, evidence from waste management and the pursuit of energy efficiency suggests that these barriers might be overcome, and an outline of potential mechanisms for change is given. In bringing together insights into material efficiency from a wide range of disciplines, the paper presents a set of 20 open questions for future work.
In this paper, we review the energy requirements to make materials on a global scale by focusing on the five construction materials that dominate energy used in material production: steel, cement, ...paper, plastics and aluminium. We then estimate the possibility of reducing absolute material production energy by half, while doubling production from the present to 2050. The goal therefore is a 75 per cent reduction in energy intensity. Four technology-based strategies are investigated, regardless of cost: (i) widespread application of best available technology (BAT), (ii) BAT to cutting-edge technologies, (iii) aggressive recycling and finally, and (iv) significant improvements in recycling technologies. Taken together, these aggressive strategies could produce impressive gains, of the order of a 50-56 per cent reduction in energy intensity, but this is still short of our goal of a 75 per cent reduction. Ultimately, we face fundamental thermodynamic as well as practical constraints on our ability to improve the energy intensity of material production. A strategy to reduce demand by providing material services with less material (called 'material efficiency') is outlined as an approach to solving this dilemma.
Remanufactured products that can substitute for new products are generally claimed to save energy. These claims are made from studies that look mainly at the differences in materials production and ...manufacturing. However, when the use phase is included, the situation can change radically. In this Article, 25 case studies for eight different product categories were studied, including: (1) furniture, (2) clothing, (3) computers, (4) electric motors, (5) tires, (6) appliances, (7) engines, and (8) toner cartridges. For most of these products, the use phase energy dominates that for materials production and manufacturing combined. As a result, small changes in use phase efficiency can overwhelm the claimed savings from materials production and manufacturing. These use phase energy changes are primarily due to efficiency improvements in new products, and efficiency degradation in remanufactured products. For those products with no, or an unchanging, use phase energy requirement, remanufacturing can save energy. For the 25 cases, we found that 8 cases clearly saved energy, 6 did not, and 11 were too close to call. In some cases, we could examine how the energy savings potential of remanufacturing has changed over time. Specifically, during times of significant improvements in energy efficiency, remanufacturing would often not save energy. A general design trend seems to be to add power to a previously unpowered product, and then to improve on the energy efficiency of the product over time. These trends tend to undermine the energy savings potential of remanufacturing.
Summary
Prospective environmental assessment of emerging technology is necessary in order to inform designers of beneficial changes early in a technology's development, and policy makers looking to ...fund projects and nudge manufacturers toward the most sustainable application of a technology. Existing analyses often have shortcomings such as failing to consider the environmental impacts in all stages of a product's life cycle; implicitly assuming that the emerging technology will be cost‐effective wherever it is technically viable; and assuming optimistic application scenarios that discontinue long‐established trends in human behavior. In this article, we propose a new approach, complementary to the prospective and anticipatory life cycle assessment literature, addressing the above concerns and attempting to make sense of the large uncertainties inherent in such analyses by using distributions to model all the inputs. The paper focuses on emerging manufacturing technologies, such as incremental sheet forming (ISF), but the issues examined are also applicable to new end‐use products, such as autonomous vehicles. This paper makes use of approaches (such as Bass modeling and product cannibalization considerations) familiar to those in the business community who anticipate market diffusion of a new technology and the effect on existing technology sales. The proposed methodology is demonstrated by estimating the potential environmental impacts in the U.S. car industry by 2030 of an emerging double‐sided ISF process. Energy and cost models of ISF and drawing are used to estimate potential mean savings of around 100 TJprimary and 60 million U.S. dollars per year by 2030.
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Industrial emissions must be dramatically reduced to avoid the potentially dangerous effects of climate change. In order to contribute to the necessary cuts, this article focuses on ...the energy and material efficiency of sheet metal forming. The processes considered include traditional methods, such as drawing and stretch forming, and newer technologies developed in recent decades such as hydroforming (fluid cell forming), superplastic forming, and incremental sheet forming.
In this analysis, we conduct case studies on forming processes at leading US car and aerospace manufacturers. The case studies include electrical power measurements on the forming machines and also consider the impacts of making the dies, sheet metal, and lubricant. Cradle-to-gate energy demands and environmental impacts are modeled in SimaPro using data based on ecoinvent 3.1 database values. The results show that idling consumes significant electricity; however, other than for incremental forming, the impacts of press electricity are small compared to the impacts of making the sheet metal. The case studies inform generalized models for each process that allow per part impacts to be estimated based only on final part material, size (surface area, thickness, and depth), and the number of parts produced over the die-set lifespan. The models are used to investigate the potential to reduce cradle-to-gate energy requirements by using incremental forming instead of drawing to form parts. It is found that there are significant potential savings for small production runs, consistent with part development/prototyping. However, these savings vary depending on the part size and the relative buy-to-fly ratio (material yield) of the two processes.
The results of this study highlight that for small production numbers over the die lifespan the impacts of die-making are important. However, as production numbers increase above one hundred parts per die-set, the impacts of making the sheet metal become dominant. It is therefore concluded that researchers interested in reducing the environmental impacts of sheet metal forming concentrate on innovations that would reduce sheet metal blanking and post-forming trimming losses.
Life cycle assessment is a technique to assess environmental aspects associated with a product or process by identifying energy, materials, and emissions over its life cycle. The energy analysis ...includes four stages of a life cycle: material production phase, manufacturing phase, use phase, and end-of-life phase. In this study, the life cycle energy of fiber-reinforced composites manufactured by using the pultrusion process was analyzed. For more widespread use of composites, it is critical to estimate how much energy is consumed during the lifetime of the composites compared to other materials. In particular, we evaluated a potential for composite materials to save energy in automotive applications. A hybrid model, which combines process analysis with economic input–output analysis, was used to capture both direct and indirect energy consumption of the pultrusion process in the material production and manufacturing stages.
Material efficiency: providing material services with less material production Allwood, Julian M.; Ashby, Michael F.; Gutowski, Timothy G. ...
Philosophical transactions of the Royal Society of London. Series A: Mathematical, physical, and engineering sciences,
03/2013, Letnik:
371, Številka:
1986
Journal Article
Recenzirano
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Material efficiency, as discussed in this Meeting Issue, entails the pursuit of the technical strategies, business models, consumer preferences and policy instruments that would lead to a substantial ...reduction in the production of high-volume energy-intensive materials required to deliver human well-being. This paper, which introduces a Discussion Meeting Issue on the topic of material efficiency, aims to give an overview of current thinking on the topic, spanning environmental, engineering, economics, sociology and policy issues. The motivations for material efficiency include reducing energy demand, reducing the emissions and other environmental impacts of industry, and increasing national resource security. There are many technical strategies that might bring it about, and these could mainly be implemented today if preferred by customers or producers. However, current economic structures favour the substitution of material for labour, and consumer preferences for material consumption appear to continue even beyond the point at which increased consumption provides any increase in well-being. Therefore, policy will be required to stimulate material efficiency. A theoretically ideal policy measure, such as a carbon price, would internalize the externality of emissions associated with material production, and thus motivate change directly. However, implementation of such a measure has proved elusive, and instead the adjustment of existing government purchasing policies or existing regulations- for instance to do with building design, planning or vehicle standards-is likely to have a more immediate effect.
This work focuses on developing a concise representation of the material recycling potential for products at end-of life. To do this we propose a model similar to the "Sherwood Plot", but for ...products rather than for dilute mixtures. The difference is reflected in the material composition and the processing systems used for the two different applications. Cost estimates for product recycling systems are developed using Shannon's information theory. The resulting model is able to resolve the material recycling potential for a wide range of end-of-life products with vastly different material compositions and recycling rates in the U.S. Preliminary data on historical trends in product design suggest a significant shift toward less recyclable products.