| 31. |
- Ekvall, Tomas, 1963, et al.
(författare)
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Incentives for recycling and incineration in LCA: Polymers in Product Environmental Footprints
- 2021
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- For material recycling to occur, waste material from a product life cycle must be made available for recycling and then used in the production of a new product. When recycling is beneficial for the environment, the LCA results should give incentives to collection for recycling and also to the use of recycled material in new products. However, most established methods for modelling recycling in LCA risk giving little or even wrong incentives. Many methods, such as the Circular Footprint Formula (CFF) in a Product Environmental Footprint (PEF), assign some of the environmental benefits of recycling to the product that uses recycled materials. This means that the incentive to send used products for recycling will be lower. If energy recovery also provides an environmental benefit, because the energy recovered substitutes energy supplied with a greater environmental impact, the LCA results may indicate that the waste should instead be sent to incineration – even when recycling is the environmentally preferable option for the society. This study aims to increase the knowledge on the extent to which PEF results, and LCA results in general, risk giving incorrect incentives for energy recovery from plastic waste. Our calculations focus on the climate impact of the recycling and incineration of LDPE waste generated in Sweden. Since this is a pilot study, we use easily available input data only. We estimate the net climate benefit through simple substitution, where recycled material is assumed to replace virgin material and where energy recovered from LDPE waste is assumed to replace average Swedish district heat and electricity. We then apply the CFF to find whether a PEF would give the same indications. Our results show no risk of a PEF or LCA giving incorrect climate incentives for incineration of fossil LDPE. However, an LCA can wrongly indicate that renewable LDPE should be incinerated rather than recycled. Our results indicate this can happen in a PEF when the heat and electricity substituted by incineration has 40-200% more climate impact than the Swedish average district heat and electricity. Our study also aims to increase knowledge about the extent to which correct incentives can be obtained through a more thorough analysis of incineration with energy recovery – specifically, through: 1. a deeper understanding of Factor B, which in the CFF can be used to assign part of the burdens and benefits of energy recovery to the energy instead of the product investigated, but which in the PEF guidelines by default is set to 0, or 2. a broader systems perspective that accounts for the effects of energy recovery on waste imports and thus waste management in other countries. We estimate Factor B based on the observation that waste incineration can be described as a process with multiple jointly determining functions. Waste treatment and energy recovery both contribute to driving investments in incineration. This, in turn, defines the volume of waste incinerated, the quantity of energy recovered, and the quantity of energy substituted. We propose that expected revenues from gate fees and energy are an appropriate basis for calculating Factor B. Up-to-date estimates of the expected revenues in the relevant region should ideally be used for the calculations. Lacking such data,we suggest the value B=0.6 can be used in the CFF when modelling waste incineration in Sweden. Our PEF calculations with Factor B=0.6 indicate such a PEF will identify the environmentally best option for plastic waste management in almost all cases. However, this is at least in part luck: Factor B will vary over time and between locations, and other parts of the CFF varies between materials. To account for the broader systems perspective, we develop two scenarios based on different assumptions on whether change in Swedish waste imports affects the incineration or landfilling in other European countries. The scenarios bring a large uncertainty into the results. This uncertainty is real in the sense that it is difficult to know how a change in Swedish waste imports in the end will affect waste management in other countries. The uncertainty still makes it difficult to draw conclusions on whether renewable LDPE should be recycled or incinerated. Our suggestions for Factor B and European scenarios both make the CFF more balanced and consistent: it now recognizes that not only recycling but alsoenergy recovery depends on more than the flow of waste from the life cycle investigated. However, neither Factor B nor the broader systems perspective amends the fact that LCA tends to focus on one product at a time. This might not be enough to guide a development that requires coordinated or concerted actions between actors in different life cycles – such as increased recycling or energy recovery. Assessing decisions in one product life cycle at a time might in this context be compared to independently assessing the action of clapping one hand. This will most probably not result in an applaud. Besides a more thorough assessment of energy recovery, we also discuss the option to give correct incentives for recycling from LCA by assigning the full environmental benefit of recycling to the product that generates waste for recycling but also to the product where the recycled material is used. We find that this 100/100 approach can give negative LCA results for products produced from recycled material and recycled to a high degree after recycling, because the benefits of recycling are counted twice. The LCA results would indicate that you save material resources by producing and recycling such products without ever using them. The 100/100 approach also lacks additivity, does not model foreseeable consequences, and does not assign a well-defined environmental value to the recovered secondary material. To guide concerted actions, like recycling or energy recovery, it seems systems analysis should ideally assess the necessary actions in combination. Many situations require the environmental impacts to be estimated for a specific product or a specific action. In some cases, however, the LCA results can be calculated and presented with, for example, the following introduction: “When the material is sent to recycling, you will, together with the recycler and the actor using the recycled material, jointly achieve this net environmental benefit: …” Such joint assessment of supply and demand for secondary materials means the allocation problem is avoided. It is also consistent with the recommendation in the old SETAC “Code of Practice” to assess life cycles with recycling by studying the inputs and outputs from the total linked system.
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| 32. |
- Ekvall, Tomas, 1963, et al.
(författare)
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Modelling incineration for more accurate comparisons to recycling in PEF and LCA
- 2021
-
Ingår i: Waste Management. - : Elsevier BV. - 0956-053X .- 1879-2456. ; 136, s. 153-161
-
Tidskriftsartikel (refereegranskat)abstract
- When recycling is beneficial for the environment, results from a life cycle assessment (LCA) should give incentives to collection for recycling and also to the use of recycled material in new products. Many approaches for modeling recycling in LCA assign part of the environmental benefits of recycling to the product where the recycled material is used. For example, the Circular Footprint Formula in the framework for Product Environmental Footprints (PEF) assigns less than 45% of the benefits of recycling to a polymer product sent to recycling. Our calculations indicate that this creates an incorrect climate incentive for incineration of renewable LDPE, when the recovered energy substitutes energy sources with 100–300% more climate impact than the Swedish average district heat and electricity. The risk of incorrect incentives can be reduced through allocating part of the net benefits of energy recovery to the life cycle where the energy is used; we propose this part can be 60% for Sweden, but probably less in countries without a district-heating network. Alternatively, the LCA can include the alternative treatment of waste that is displaced at the incinerator by waste from the investigated product. These solutions both make the LCA more balanced and consistent. The allocation factor 0.6 at incineration almost eliminates the risk of incorrect incentives in a PEF of renewable polymers. However, the focus of LCA on one product at a time might still make it insufficient to guide recycling, which requires concerted actions between actors in different life cycles.
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| 33. |
- Engström, Rebecka Ericsdotter, 1984-
(författare)
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Exploring cross-resource impacts of urban sustainability measures : an urban climate-land-energy-water nexus analysis
- 2022
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- In an increasingly urban world, cities' global resource uses grow. Two fundamental resources for making cities liveable are water and energy. These resources are also closely interlinked – systems that convert and deliver energy to cities require water, and urban water systems use energy. In addition, these two resource systems affect and are affected by land use and climate change. This ‘nexus’ between climate, land use, energy and water (CLEW) systems has been extensively studied in the past decade, mainly with a focus on national and transboundary CLEW systems. This doctoral thesis develops the CLEW nexus research from an urban perspective.Two quantitative analyses examine how different types of sustainability measures in cities affect intended and unintended CLEW systems. First, the CLEW impacts of a set of sustainability measures in New York City are assessed - from water conservation to emission reductions. Results show that every measure affects (to varying degrees) all studied sustainability dimensions - water, energy and climate - and that the impacts can be quantified through a reference-resource-to-service-system (RRSS).The second quantitative study focuses on how CLEW impacts from a city's sustainability efforts spread beyond local and international borders. It investigates how global water and land use are affected in alternative scenarios to achieve climate neutrality in 2030 in the town of Oskarshamn, Sweden, using an energy systems simulation model. The study finds that both the magnitude and the geographical distribution of land and water requirements vary between scenarios. A strategy to achieve climate neutrality that invests in electrification leads to increased national water use, while a strategy that relies on biofuels has a greater impact on water and land use internationally. When results are translated to interactions between the UN's sustainable development goals (SDGs), they reveal that SDG synergies and trade-offs are 'strategy-dependent': different options for achieving SDGs on energy, sustainable cities and climate action have varying consequences for the advancement of SDGs on sustainable water, food production and biodiversity.To shed light on how data challenges affect quantitative urban nexus studies, uncertainty assessments of selected thesis’ results are conducted and complemented with a thematic analysis of a set of recently published urban nexus papers. Together, they indicate that analytical choices, uncertainties in results and - as a consequence - research foci are influenced by data limitations in both this thesis and in other urban nexus studies.Lastly, the finding from the Oskarshamn analysis – that SDG interactions are strategy-dependent – is deliberated with experts within sustainability sciences and SDG interaction research. From this, a research agenda is proposed with measures to make SDG 'spillovers' visible in local level decision-making.Taken together, the thesis contributes to filling several knowledge gaps on how urban sustainability measures within the CLEW systems interact within and beyond city limits, and proposes analytical approaches to quantify these interactions. It further points out how current data challenges constrain quantitative urban nexus analyses and highlights research needs to improve data management as well as other key efforts to enable consideration of nexus interactions, including SDG 'spillovers', in cities' sustainability work.
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| 34. |
- Eriksson, Mattias, et al.
(författare)
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Food waste reduction in supermarkets - Net costs and benefits of reduced storage temperature
- 2016
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Ingår i: Resources, Conservation and Recycling. - : Elsevier BV. - 0921-3449. ; 107, s. 73-81
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Tidskriftsartikel (refereegranskat)abstract
- Food waste is a major problem and therefore measures are needed to reduce it. Since expired best-before date is a frequently cited cause of food waste in supermarkets, prolonging shelf life could reduce food waste. Longer shelf life could be achieved in different ways, e.g. reduced storage temperature. However, there is limited knowledge regarding the extent to which longer shelf life actually leads to reduced food waste, and whether the benefits of reduced waste exceed the increased energy costs of maintaining reduced storage temperature. Therefore this study calculated the net effect of reducing food waste in supermarkets by reducing the storage temperature through simulating the relationships between food waste reduction, longer shelf life, reduced storage temperature and increased energy costs.A case study was performed using three years of data on cheese, dairy, deli and meat product waste in six Swedish supermarkets, together with published data on microbiological growth at different temperatures and on the energy requirement for cold storage at different temperatures. Food waste was found to be reduced with lower storage temperature for all food products tested. This measure gave increasing net savings in terms of money and greenhouse gas emissions for meat products with decreasing storage temperature. Deli products had net savings close to zero, while for dairy and cheese products there were net losses, since the costs of reducing storage temperature exceeded the potential savings. Therefore, reducing storage temperature has the potential to reduce waste, but at a total net cost. However, a net benefit can be achieved if the measure is only introduced for products with high relative waste, low turnover and high value per unit mass. (C) 2015 Elsevier B.V. All rights reserved.
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| 35. |
- Gebremeskel, Dawit, et al.
(författare)
-
Long-term electricity supply modelling in the context of developing countries: The OSeMOSYS-LEAP soft-linking approach for Ethiopia
- 2023
-
Ingår i: Energy Strategy Reviews. - : Elsevier BV. - 2211-467X. ; 45
-
Forskningsöversikt (refereegranskat)abstract
- Long-term power supply modelling is particularly important for developing countries in providing sustainable solutions to electricity problems. This study presents the first detailed and complete model of the Ethiopian electricity system while considering the unique features (dominance of traditional energy, informal economy, urban-rural divide, low electrification, supply shortage, etc.) and context of developing countries that is developed by soft-linking the OSeMOSYS (Open-Source energy Modelling System) and LEAP (Long-range Energy Alternatives Planning System) modelling frameworks. Better system representation and design of plausible scenarios that explore the potential pathways of the future power supply and demand evolution until 2050 is done by performing sensitivity analysis. Sector wise and technological representation of supply and end-uses at a disaggregated level, assessment of centralized grid-based means and decentralized off-grid methods for improving electricity access are the main methodological contributions. Five policy scenarios are employed to explore different possible futures and balance the long-term electricity needs and resources. The improved efficiency scenario reduces the installed capacity by 9 GW which translates into approximately 11% total discounted cost saving (USD $ 4 billion). This economic benefit has made the efficiency scenario the most desirable compared to the other scenarios. Attributed to lower investment costs and abundant resource availability, the results show that renewable technologies are more competitive and favourable.
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| 36. |
- Haraldsson, Joakim, 1990-, et al.
(författare)
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Impact analysis of energy efficiency measures in the electrolysis process in primary aluminium production
- 2019
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Ingår i: WEENTECH Proceedings in Energy. ; , s. 177-184
-
Konferensbidrag (refereegranskat)abstract
- The Paris Agreement includes the goals of ‘holding the increase in the global average temperature to well below 2°C above pre-industrial levels’ and ‘making finance flows consistent with a pathway towards low greenhouse gas emissions’. Industrial energy efficiency will play an important role in meeting those goals as well as becoming a competitive advantage due to reduced costs for companies. The aluminium industry is energy intensive and uses fossil fuels both for energy purposes and as reaction material. Additionally, the aluminium industry uses significant amounts of electricity. The electrolysis process in the primary production of aluminium is the most energy- and carbon-intensive process within the aluminium industry. The aim of this paper is to study the effects on primary energy use, greenhouse gas emissions and costs when three energy efficiency measures are implemented in the electrolysis process. The effects on the primary energy use, greenhouse gas emissions and costs are calculated by multiplying the savings in final energy use by a primary energy factor, emissions factor and price of electricity, respectively. The results showed significant savings in primary energy demand, greenhouse gas emissions and cost from the implementation of the three measures. These results only indicate the size of the potential savings and a site-specific investigation needs to be conducted for each plant. This paper is a part of a research project conducted in close cooperation with the Swedish aluminium industry.
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| 37. |
- Heeren, Niko, et al.
(författare)
-
Towards a 2000 Watt society assessing building-specific saving potentials of the Swiss residential building stock
- 2011
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Ingår i: World Sustainable Building Conference 2011, October 18-21, 2011, Helsinki, Finland.
-
Konferensbidrag (refereegranskat)abstract
- Switzerland declared the notion of the 2000 Watt society as their leitmotif towards a sustainable development in terms of energy. This implies that worldwide, no more than 17520 kWh of total primary energy and 1 ton CO2-eq. are to be consumed per capita and year for all services. Thus, in order to meet the targets of the 2000-Watt society, it is necessary to reduce primary energy demand by 44% and greenhouse gas emissions by 77%. The building stock model, described in this paper, assisted the government of Zurich to identify the necessary steps in order to achieve the goals with regard to the city‟s residential, school, and office buildings. The objective of this paper is to investigate the role of energy demand reduction in residential buildings on the way towards the goals of a 2000-Watt society.In order to illustrate the mechanisms within the building stock and to identify the effects of construction activity, the model works with different scenarios. Specific measures were isolated and analysed individually. All three measures act directly on the building stock; each have comparable reduction potential in terms of primary energy demand (ca. 15%) and greenhouse gas emissions (ca. 40%). In order to further cut back greenhouse gas emissions, measures to reduce carbon intensity of fuels and electricity need to be considered.
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| 38. |
- Hermansson, Frida, 1988
(författare)
-
Assessing the future environmental impact of lignin-based and recycled carbon fibres in composites using life cycle assessment
- 2020
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Carbon fibre reinforced polymers (CFRPs) are composite materials that are gaining attention for their lightweighting and strengthening properties in a wide range of applications. However, using them instead of conventional materials (such as steel or other composites) does not automatically lead to a decrease in life cycle climate impact or energy use. This is the result of the energy-intensive production of the carbon fibres. Two routes that could mitigate this problem are: 1) the use of lignin for carbon fibre production and 2) the use of recycled carbon fibres. This thesis assesses how these two routes could decrease the environmental impact of carbon fibres in composites, and how challenges connected to assessing these emerging technologies can be handled using life cycle assessment (LCA). The two routes were assessed by conducting a meta-analysis of earlier LCAs of CFRPs and lignin production and three different LCA case studies. Results show that both using lignin as a raw material and using recycled carbon fibres have good potential to decrease the environmental impact of CFRPs, making them more environmentally competitive than other materials. It was found that the transition from polyacrylonitrile (PAN) to lignin as a raw material has good potential to decrease the environmental impact of future carbon fibres. However, the extent of this potential depends on both internal factors, such as process development, and external factors, such as the development of the lignin market and the future energy supply system.
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| 39. |
- Hermansson, Frida, 1988, et al.
(författare)
-
Environmental Challenges and Opportunities of Lignin
- 2019
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Lignin is the most abundant bio-polymer on Earth, gluing the cellulose and hemicellulose fibers together in the tree stem and providing stiffness. Lignin is presently mostly available in side streams of biorefineries and pulp mills (e.g. in the black liquor of the Kraft pulp mill). It is almost always combusted for internal energy use at the plant due to its present low market value. Though lignin can be extracted and valorized, for example via acidification followed by precipitation and membrane filtration or by solvent extraction, this is seldom done today. Nevertheless, lignin is gradually being considered an interesting raw material for various products and applications, ranging from biofuels to carbon fibers. However, in environmental life cycle assessments of lignin-based products, the environmental impacts of lignin production typically have not been accounted for with the rational that lignin is a waste that needs to be taken care off.This argument will no longer be valid when lignin extraction processes are further developed and various markets for lignin open up. Conducting a life cycle assessment of lignin production is complicated. As lignin is a product of a multi-output process, there will be inherent challenges regarding the choice of system expansion or how to allocate environmental impacts to this product and to other products. Allocation based on economic values is particularly challenging as the market price of lignin and of other products from the process is the basis for allocating impacts, and the future market development for lignin is still rather unexplored and uncertain. The same challenge can be applied to system expansion, as what is being substituted could change in the future. The aim of the presented study is to provide guidance on how to better assess lignin production in life cycle assessments. The cradle-to-gate environmental impacts of 1 kg of lignin from a Kraft pulp mill is assessed. Different allocation methods as well system expansion by substitution will be applied to the multi-output process to assess and illustrate what influence these will have on the final environmental impacts of the lignin.
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| 40. |
- Hermansson, Frida, 1988, et al.
(författare)
-
Life cycle assessment of lignin-based carbon fibres
- 2018
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- As vehicle manufacturers attempt to decrease the weight of their products, and consequently the fuel consumption during the use phase, carbon fibre reinforced polymers, CFRPs, are becoming more common. However, as the carbon fibre production route has proven to be very energy intensive, CFRP may not perform as well as conventional materials such as steel when using an environmental life cycle perspective. Carbon fibres are usually made from polyacrylonitrile, PAN, a fossil-based polymer. Research has shown that a possible route to reduce the environmental impact from carbon fibres is to replace PAN with a bio-based alternative, such as lignin. Lignin is a main by-product of many biorefinery processes that use ligno-cellulosic material as feedstock. A switch to lignin instead of PAN could reduce the environmental impact of the carbon fibres, decrease the dependence on oil as well as reduce the cost of the carbon fibres. This paper, which is a part of Frida Hermansson PhD-project will include findings from the life cycle assessment of lignin-based carbon fibres as well as discuss how different allocation methods will have effect on the final results. The production of lignin-based carbon fibres was assessed using life cycle assessment. The functional unit was 1 kg of carbon fibres at the factory gate. Results show that replacing PAN with lignin as a precursor fibre material could decrease the energy consumption as well as climate impact. However, as lignin is bio-based, land use will increase. The impact results for the lignin-based carbon fibres largely depend on how much of the environmental impact is allocated to lignin for a given biorefinery process. Lignin’s relatively low price in combination with its large quantity leads to the economic allocation method being the most favourable. Lignin has long been considered a waste product, but as the demand for lignin increases so should the price. This means that the type of allocation applied will have significant influence on the environmental impacts of lignin-based carbon fibres.
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