Attributional Life Cycle Assessment Research Articles

Environmental impacts and scale-up efficiency of four carbon capture and storage scenarios

Capture, transportation, and permanent storage of CO2 is considered pivotal in reaching global net-zero emission targets. Conceptualization and deployment of carbon capture and storage (CCS) value chains require substantial resources with current CCS projects trailing behind expectations. To date few studies address the environmental impacts related to introducing CCS into existing value chains, and even fewer focus on the environmental efficiency of scaling-up CCS projects, despite the need for acceleration. Four scenarios were studied, resembling CCS projects at different capture capacities of 0.3, 1.5, 3.5 and 10 million tonnes of CO2 per year (mtpa) deployed within a Northern European region. Using attributional life cycle assessment, we demonstrate that permanent carbon storage today may furnish a 47–91% CO2 net-abatement potential depending on the CO2 source and geographical location of CCS projects. Despite limited operational data, results appear robust with general low uncertainty. Our environmental assessment show that capturing, conditioning and liquefaction account for the largest emission shares of the studied CCS value chains, ranging from 70 to 80%, which is heavily fluctuated by the carbon emission intensity of regional electricity production. Impacts related to permanent storage activities, such as offshore monitoring and well drilling are limited to less than 2% across all scenarios. Moreover, our study suggests that expanding the spatial geographical scope to accumulated 5000 km has a low influence on the efficiency of CCS value chains regardless of capture rate. Freshwater eutrophication shows the highest burden across the assessed environmental impact categories caused by the electricity production for capture processes. Lastly, we identify net-abatement improvement potential for post-combustion CCS projects at capturing capacities between 1.5 and 10 million tonnes per annum ranging from 10 to 20% for transport-related activities, and 60–68% for capturing processes when assuming net-zero energy scenarios.

Evaluation of hydrothermal carbonization of biomass residues for bioenergy: A life-cycle based comparison against incumbent technologies

Hydrothermal carbonization of biowaste with energy recovery was evaluated as a biowaste treatment technology using attributional life cycle assessment carried out in line with ISO 14044. Results show that important differences were observed for individual impact categories. Hydrothermal carbonization outperformed all other incumbent technologies in three impact categories and performed on par with anaerobic digestion and composting in the climate change category, where impact scores across three different wet biowaste streams ranged from -0.014 to -0.032 kg CO2 equivalents per kg of wet biowaste treated. However, it performed the worst in those environmental impacts which address resource depletion, including mineral, fossil and renewable resource depletion. This stresses the need to include all impact categories when evaluating environmental performance of biowaste treatment technologies. Differences in the ranking between different midpoint categories corroborate earlier studies suggesting that the general waste hierarchy might not necessarily apply to hydrothermal carbonization of biowaste.

Assessing robustness of consequential LCA: Insights from a multiregional economic model tailored to the cement industrial symbiosis

AbstractOne of the key challenges in conducting consequential life cycle assessment (LCA) is to identify and quantify what is likely to be affected by changes in market behavior—so‐called marginal effects. Although the critical importance of uncertainty and sensitivity assessments in attributional LCA is recognized, they are rarely conducted in consequential studies. Thus, this paper aims to address two objectives: first, to examine the uncertainty and robustness of marginal effects in consequential LCA and second, to identify the most influential group of inputs contributing to the overall variance in climate change impact scores. To accomplish this, the study employs an enhanced consequential LCA framework that integrates a multiregional economic optimization model with consequential LCA tools. The framework is applied to assess the climate implications of a 6% increase in clinker substitution within average Eastern North American cement production by 2030, relative to 2020 levels. Through this framework, a Monte Carlo simulation is conducted to evaluate the dispersion of the results. Subsequently, a variance‐based one‐at‐a‐time sensitivity analysis is performed to rank the most influential groups of inputs affecting the robustness of result across macroeconomic, material flow, economic, transport, and consequential life cycle inventory databases. Afterward, a conceptual framework is proposed to guide practitioners in prioritizing areas for testing consequential LCA results based on region‐specific information. This work aims to contribute to decision‐makers' access to more reliable information to support the development of effective environmental regulatory measures.

Consequential life cycle assessment of bamboo leaf ash generation: A Brazilian context

The potential of biomass growth, such as from bamboo leaves, as a source of electricity provides an optimistic scenario for the sustainable development of new green building materials. To validate robust life cycle inventory (LCI) data for incoming high-quality silica sources for cementitious materials, a consequential life cycle assessment (CLCA) on the bamboo leaves ash (BLA) with a prospective approach was conducted. The LCI data was collected in Southeastern Brazil with a prospective maturity in biomass electricity system. The data was gathered by analyzing the various stages involved in the production of BLA, including bamboo cultivation, leaf collection, cogeneration, raw BLA beneficiation, and its impact on cement and electricity marginal production systems. According to the multifunctionality solution, the environmental impacts results of CLCA were discussed using a sensibility analysis with two attributional life cycle assessment (ALCA) scenarios as allocation and “zero environmental load” (considering BLA as residue). The scenarios demonstrate the potential for sustainable use of BLA, especially for its impact on climate change, including the biogenic carbon category. Also, consequences such as avoiding BLA landfilling and increasing the potential for bamboo agricultural holdings to become energy independent was included in the study conclusion. While these results are positive, the prospect of maturing electricity production requires the development of other high-quality materials, such as sugarcane bagasse ash, sugarcane leaf ash and rice husk ash. However, the positives consequences did not overcome the negative impacts from the transportation of BLA into its system boundaries, once the highway transport model is the manly in the Brazilian context. Hence, this study provides important and reproducible pathways for developing LCI data on other biomass ashes, assisting future studies on green building materials.

Consequential versus attributional life cycle optimization of poultry manure management technologies in a food-energy-water-waste nexus

To model the environmental and economic tradeoffs of managing poultry manure wastes in a food-energy-water-waste nexus, this work builds a framework to conduct a combined life cycle and techno-economic optimization and a spatial analysis of poultry manure management technologies. To align with the United Nations Sustainable Development Goals 6: Clean Water and Sanitation and 13: Climate Action by mitigating the massive water and climate impacts induced by the common practice of fertilizer crops using direct land application of poultry manure, the framework minimizes freshwater eutrophication (FE) impact and climate change impact (GWP). To account for the circular economy, the net present value (NPV) is maximized to measure the economic feasibility of implementing alternative management pathways. A multi-objective mixed-integer non-linear programming framework accounts for the selection of direct land application, and waste to energy technologies, spatial variation in manure supply, facility sizing, and the products’ consumption and end-of-life. This optimization framework is evaluated for a case study in New York state. Under an attributional life cycle optimization, anaerobic digestion minimizes FE with an impact of 0.002 kg P-eq/ton manure, while using a consequential life cycle optimization, hydrothermal carbonization minimizes FE with an impact of −0.96 kg P-eq/ton manure. For both life cycle methodologies, pyrolysis with land application of biochar minimizes GWP. At the attributional life cycle assessment tradeoff point for GWP and NPV, minimum carbon credits of US$33/ton CO2-eq are necessary for a pyrolysis plant to have a positive NPV, implying that harnessing economies of scale or robust carbon accounting is necessary for the widespread adoption of pyrolysis as a poultry manure management technology.

Forest dynamics in LCA: Integrating carbon fluxes from forest management systems into the life cycle assessment of a building

The urgent issue of climate change has sparked increasing interest in using wood to reduce buildings' greenhouse gas emissions (GHGe). While attributional life cycle assessment (LCA) methods are commonly employed to estimate GHGe from buildings, they lack a temporal distribution of carbon fluxes from biogenic materials, overlooking forest management impacts on emissions and sequestration. Consequently, we investigated the integration of forest and building systems, examining emissions associated with three different forest management scenarios at stand and landscape levels. Our findings suggest a 6 % to 81 % lower GHGe for the building using this study's approach compared to the static methodology recommended by the European Standard EN16485 in a 50 year perspective. However, the accumulated impact over the building's lifetime remains similar. Hence, both methods incentivize building designers’ to use wood to lower GHGe, although the dynamic integration postpones benefits from the forests' carbon sequestration to later stages of the building's lifetime.

Life cycle assessment of active spring frost protection methods in viticulture: A framework to compare different technologies

In viticulture, the risk of spring frost is mainly due to earlier budbreak, increasing the vulnerability of buds and green organs to freezing temperatures. Active Spring Frost Protection Methods (ASFPMs) aim to mitigate this risk by increasing the temperature in the bud area. ASFPMs are often seen as highly labour-intensive and resource consuming practices. ASFPM technologies are diverse and influenced by different external drivers, affecting differently their application strategies and the required equipment for efficiency. This study proposes a framework for analysing and comparing ASFPMs’ potential environmental impacts using Life Cycle Assessment (LCA) methodology. We illustrate this proposal with an example: Winter cover, wind machine, sprinkler and anti-frost candles comparison in Loire Valley conditions. We modeled the attributional LCAs with Impact world + characterisation method using Abribalyse 3.1 and Ecoinvent 3.8 databases. Application and climatic scenarios were elaborated to set conditions of ASFPMs use. The overall combination of attributional LCAs and external scenarios designs a context-specific LCA. Required time of application for each ASFPM to protect 1 ha during frost hours was determined using linear regression of ASFPM application time in function of total seasonal frost hours based on a recent decade (2013–2023). Sensitivity analysis consisted in varying frost hours theoretically with a step of 1 unit, using the lowest and highest frost hour numbers from 2013 to 2023 as boundaries. Overall, the ranking between ASFPM environmental scores changes based on the theoretical frost duration. The implementation of context-specific elements allowed for the development of system boundaries in attributional LCA, enabling the analysis and comparison of different types of technologies. The framework of this study showed its relevance in the context of ASFPM technologies through a concrete example in Loire Valley viticulture. Future research may consider other contextual elements and ASFPM technologies. This framework could be used in different fields of study to analyse and compare contrasted technologies in terms of environmental impacts.

Systematising the LCA approaches’ soup: a framework based on text mining

PurposeIt is challenging for practitioners to navigate through the multitude of life cycle assessment (LCA) approaches due to the rich literature and a lack of systematisation. The LCA flexibility allowed by standards results in a multitude of applications and, as referred to in previous works, as an “alphabet soup”. This paper proposes a scheme for a clearer classification of currently used LCA approaches, with consideration of the 4-stage framework coming from standards.MethodsThis systematisation was first established through literature research serving as a preliminary tentative framework. A text mining task was carried out in a second stage, involving 2044 published articles among 7558 of the last 10 years. For text mining, a dictionary collected keywords and synonyms of the LCA approaches. Such keywords were then extracted from the text together with their context (multiword). The final multiword analysis allowed the association of each keyword (i.e. each LCA approach) with a specific LCA stage (Goal and Scope, Life Cycle Inventory, Life Cycle Impact Assessment, Interpretation). The preliminary framework was adapted, further enriched and validated based on the text mining results.ResultsAs a result of the text mining activities, the preliminary tentative framework was partially confirmed and enriched with new insights, especially in the field of “explorative” LCA approaches, which also include “prospective” and “scenario-based” LCA. For most of the currently used LCA approaches, a link to a unique LCA stage was not recorded. However, clear trends were detected. The text mining task also highlighted a high number of works in which different approaches are compared or counterposed, especially in the field of attributional and consequential LCA. Some issues were found with the connotations of “traditional” approaches, which could be defined more specifically as “non-explorative”.ConclusionsUnlike other works focused on notions from selected literature, text mining activities can provide bottom-up feedback on a larger scale more automatically. In addition, this work brought out novel LCA approaches, for which future developments will confirm a final definition and systematisation. As an additional advantage, the presented methodology is easily replicable. Hence, the presented framework can be updated along with developments in LCA approaches.

LCA-based environmental benefit allocation between steel and cement industries in steel byproduct recycling

Among the steel byproducts, more than 80% of blast furnace slag is recycled in the cement industry. However, the criteria for allocating environmental benefits between the steel and cement industries need to be more transparent. This study aims to allocate the environmental benefits between the steel and cement industries when granulated blast furnace slag (GBFS) is recycled to replace Portland cement in the production of slag cement (SC). Specifically, this research proposes how the recycling of GBFS, a byproduct of the steel production process, can quantify environmental burdens and benefits from both attributional life cycle assessment (ALCA) and consequential life cycle assessment (CLCA) perspectives. It also suggests methods for allocating these environmental benefits between the steel and cement industries. Following the final agreement on the EU Carbon Border Adjustment Mechanism (CBAM), this study emphasizes the growing importance of interconnected allocation of environmental benefits through recycling. Various allocation methods using ALCA and CLCA approaches have been assessed, significantly impacting the analysis results. Furthermore, these findings of the study are expected to provide guidance for potential policy decisions and internal decision-making processes, highlighting the environmental benefits that GBFS recycling offers to both steel and cement industries.

Towards circularity in aquaculture systems: Environmental impact of Hermetia illucens meal inclusion in diets for rainbow trout reared in aquaponics

In advancing towards more sustainable aquaculture, the inclusion of insect meals in aquafeeds has significant potential to increase circularity and reduce environmental impacts, especially in aquaponics. Nevertheless, there is a lack of information regarding the environmental performance of these innovative feeding and management solutions. This study assessed the environmental impact associated with the dietary inclusion of Hermetia illucens (HI) meal (0%, 6% and 12%) in diets for rainbow trout (Oncorhynchus mykiss) reared in a low-tech aquaponic system characterised by nine independent experimental units (6.06 kg/m3 of fish and 14 strawberry plants per unit). A cradle-to-gate attributional life cycle assessment model was used to consider the impacts related to the whole aquaponic system (AQ-FISH) and those only related to the production and use of the aquafeed (AQ-FEED). The impact categories were 100-year global warming (kg CO2-eq) – with (GWP_LUC) and without (GWP) the emissions associated with land-use change (LUC), acidification (AP, g SO2-eq) and eutrophication (EP, g PO4-eq) potentials, cumulative energy demand (CED, MJ), land occupation (LO, m2/y) and water scarcity (WS, m3-eq). The functional unit was a 1 kg live weight increase of rainbow trout. Data originated from a previous 76-d fish performance trial. Data regarding HI meal were derived from an interview with the manufacturer. An economic method was used to partition the impacts between HI meal, HI fat and the frass (exhausted substrate). The effect of the HI meal inclusion level on the AQ-FISH and AQ-FEED impact values was tested using one-way analysis of variance.A 1 kg live weight increase of rainbow trout reared in the aquaponic system (AQ-FISH) produced 15.6 kg CO2-eq (GWP), 18.3 kg CO2-eq (GWP_LUC), 67 SO2-eq and 55 g PO4-eq and used 354 MJ, 3.5 m2/y and 311 m3-eq. The dietary inclusion of HI meal did not affect the AQ-FISH results, except for CED (+2%–5%). When considering the impact resulting from feed production (AQ-FEED), the inclusion of HI meal did not affect GWP_LUC, AP, EP and LO, but it negatively affected GWP (+13%–26%) and CED (+34%–68%). Results from AQ-FISH and AQ-FEED scenarios showed low sensitivity to the methodological choices. Overall, our findings suggest that general improvements to reduce the environmental impact associated with rainbow trout production in aquaponics should be concurrently directed towards both the system setting and management, as well as towards the HI meal production process, with a particular emphasis on enhancing energy efficiency. To minimise potential trade-offs, especially from an environmental perspective, future studies should prioritise the investigation of energy use and greenhouse gas emission associated with feed production. This requires a thorough evaluation of all changes in the diet formulation resulting from the inclusion of a new ingredient.

Embodied Carbon Impacts of Building Envelope Systems

Abstract As buildings become more energy efficient due to stringent building codes, the emphasis on reducing the embodied carbon (EC) in the built environment has become significant. Studies predict that between 2020 and 2050, new buildings will surpass operational emissions with higher embodied emissions in their initial decade and throughout their life cycle. To meet decarbonization targets, reducing EC through low-carbon, high-performance building designs and grid decarbonization is crucial. This research analyzes the embodied carbon intensity of 26 commonly used envelope systems of large buildings in Ontario’s Greater Toronto and Hamilton Area (GTHA) using the attributional life cycle assessment (ALCA) methodology. Results highlight the impact of cladding materials, insulation layers, and backup structures on EC. The study ranks envelope assemblies based on their EC intensity (ECI), providing insights for designers to balance operational and embodied emissions. Noteworthy findings include the relatively high ECI of floor systems compared to exterior wall and roof systems. It also emphasized the challenges in assessing the environmental impacts of wood-based products and the need for uncertainty analysis and transparent reporting. The study contributes to understanding EC in building envelopes, guiding design teams toward low-carbon structures and more informed decision-making. As research progresses, recommendations include consequential analysis, assessing biogenic carbon impacts, and material durability studies for a deeper insight on the environmental impacts of building envelope materials.

Assessing the impact of climate change and water scarcity of ferronickel production in Indonesia: A life cycle assessment approach

In Indonesia, emissions from coal-fired steam power stations are the greatest environmental concern of the nickel industry. Prior researches have exclusively focused on carbon dioxide (CO2) emissions. Meanwhile, this study includes CO2 fossil and CO2 biogenic emissions as well as CO2 absorption by plants into its assessment of the climate change consequences associated with ferronickel production in Indonesia. The objective of this study is to evaluate the potential impacts of climate change and water scarcity on the nickel industry in Indonesia by implementing various power facility scenarios. The methodology chosen for this study was Attributional Life Cycle Assessment (ALCA). The impact of climate change can be reduced by 38.9 %, or from 99,024.7 to 60,522.2 kg CO2 eq/t, if coal fuel is replaced with biomass fuel in steam power plants. By replacing steam power stations fuelled by coal with hydroelectric facilities, the impact of climate change can be reduced by 96 %, from 99,024.7 to 3,993.7 kg CO2 eq/t. This results in a 12.5 % decrease in water scarcity, from 100.3 to 89.1 m3 H2O eq/t. In the nickel industry, hydroelectric power plants are more effective at mitigating climate change than steam power plants powered by coal or biomass.

Environmental impacts of Australian pork in 2020 and 2022 determined using lifecycle assessments

Context The Australian pork industry is highly efficient, with a history of ongoing productivity and environmental improvement. The introduction of economy-wide environmental targets require delivering and tracking performance improvement. Aims This study determined carbon footprint (greenhouse gas [GHG] and land use [LU] and direct land use change [dLUC] emissions, reported as kg CO2-e), fossil energy (MJ), freshwater consumption (L), water stress (L H2O-e), land occupation (m2) and eutrophication potential (nitrogen and phosphorus) for Australian pork for 2020 and 2022. Variability between housing, manure management systems, and regions were identified, and systems analysed to determine new options for low-impact pork. Methods In the largest Australian study of its kind, data for ~70% of pigs produced were collected using a stratified design. Using attributional life cycle assessment, impacts were reported per kilogram of liveweight (LW), post-processed, retail, and boneless, fat-corrected pork. Results are presented as industry averages ± 2 × s.d. Key results Key results were 3.0 ± 0.1 and 3.0 ± 0.1 kg CO2-e GHG, 0.4 ± 0.07 and 0.3 ± 0.03 kg CO2-e LU and dLUC, 12.9 ± 0.5 and 13.4 ± 0.5 MJ, 93.8 ± 9.6 and 52.5 ± 3.6 L, 68.4 ± 6.7 and 43.2 ± 3.3 L H2O-e, and 12.0 ± 0.9 and 12.7 ± 0.9 m2/kg LW in 2020 and 2022, respectively. Due to industry growth, total emissions were higher in 2022. Eutrophication potential for Australian pork (2.2 × 10−4 ± 3.0 × 10−5 kg phosphorus and 8.7 × 10−3 ± 3.5 × 10−4 kg nitrogen/kg LW), reported for the first time, was low compared with grazing systems and European piggeries. Conclusions Industry has demonstrated long-term performance improvement, though the rate slowed between 2020 and 2022. Ongoing interventions are required to return to trend. Covered pond, deep litter, and outdoor systems produce lower carbon footprint pork and can provide other environmental benefits from renewable energy, and reduced fossil energy demand. Implications There is potential to further reduce environmental impacts through practice change. If industry is to meet formal targets, investment and proactive policy settings are required to overcome barriers to adoption of existing technology and support the techno-economic case for novel strategies.

Assessing the environmental impacts of conventional and organic scenarios of rainbow trout farming in France

In France, rainbow trout farming in conventional flow-through systems raises environmental concerns. To address this, there is a growing interest in organic aquaculture. In this study, we employed an attributional life cycle assessment (LCA) to analyze the environmental impacts of rainbow trout production, comparing conventional and organic practices in a model fish farm. Our life cycle impact assessment revealed that organic farming significantly reduced environmental impacts per tonne of trout in seven of the nine selected impact categories. Notably, freshwater ecotoxicity exhibited the most significant difference, with organic systems showing a 35% decrease. The only exceptions were freshwater eutrophication and water dependence, where organic production led to higher impacts per tonne of trout. In conventional farming, emissions amounted to 14 kg of P eq./tonne, whereas in organic farming, the emissions were slightly higher (15 kg of P eq./tonne). For water dependence, one tonne of trout production in the conventional system mobilized 128 103 m3 vs. 185 103 m3 in the organic system. The environmental benefits of organic production were even more marked when using a surface-based functional unit (m2y). We demonstrated the benefits of organic trout production from an environmental perspective. However, our findings highlight the caution needed when interpreting LCA comparisons of such production systems that can be highly influenced by methodological choices such as the functional unit used.

Modeling the environmental impacts of Asparagopsis as feed, a cow toilet and slurry acidification in two synthetic dairy farms

Intensive dairy farming, particularly enteric fermentation and manure management, is a major contributor to negative impacts on the local and global environment. A wide range of abatement measures has been proposed to reduce livestock-related emissions, yet the individual and combined effects of these innovations are often unknown. In this study, we performed an attributional life cycle assessment of three innovative measures modeled in two synthetic German dairy farm systems: Feeding of the seaweed Asparagopsis, installing an in-house cow toilet system, and performing on-field slurry acidification. These measures were modeled both individually and in combination to account for single and cumulative effects and compared to a reference scenario under current practices. Our results showed that feeding high levels of Asparagopsis and the combination of all three measures were most effective at reducing global warming potential (20–30 %), while only the latter mitigated eutrophication (6–9%) and acidification potential (14–17 %). The cow toilet required additional adapted manure management (separated storage and injection of urine) to effectively reduce eutrophication (8–10 %) and acidification potential (19–23 %) and to decrease global warming potential (3–4%) and abiotic depletion (4–5%). Slurry acidification slightly affected all considered environmental impact categories. All three measures involved trade-offs, either between LCA impact categories (global warming potential vs. abiotic depletion), the location of impacts (off- vs. on-farm), or the emission reduction in individual gases (ammonia vs. nitrous oxide). Measure combinations could compensate for the observed trade-offs. Our study highlights the potential of novel abatement measures but also shows the interdependencies of measures in different stages. This calls for a revisiting of current priorities in funding and legislation, which often focus on single objectives and measures (e.g. ammonia reduction) toward the preferential use of measures that are effective without driving trade-offs or improving resource efficiency.

Access to bedding and outdoor runs for growing-finishing pigs: is it possible to improve welfare without increasing environmental impacts?

Providing bedding or access to an outdoor run are husbandry aspects intended to improve pig welfare, which is currently financially supported through animal welfare schemes in several European countries. However, they may significantly affect the environment through changes in feed efficiency and manure management. Therefore, the aim of this paper was to compare farms differing in animal welfare relevant husbandry aspects regarding (1) the welfare of growing-finishing pigs and (2) environmental impact categories such as global warming (GW), acidification (AC), and freshwater (FE) and marine eutrophication (ME), by employing an attributional Life Cycle Assessment. We collected data on 50 farms with growing-finishing pigs in seven European countries. Ten animal-based welfare indicators were aggregated into three pig welfare indices using principal component analysis. Cluster analysis of farms based on husbandry aspects resulted in three clusters: NOBED (31 farms without bedding or outdoor run), BED (11 farms with bedding only) and BEDOUT (eight farms with bedding and outdoor run). Pigs on farms with bedding (BED and BEDOUT) manipulated enrichment more often (P < 0.001), pen fixtures less frequently (P = 0.003) and showed fewer oral stereotypies (P < 0.001) than pigs on NOBED farms. There were fewer pigs with a short(er) tail on farms with than without bedding (P < 0.001). Acidification of BEDOUT and BED farms was significantly higher (compared to NOBED farms P = 0.002) due to higher ammonia emissions related to farmyard manure. Also, BEDOUT farms had higher ME than NOBED farms (P = 0.035). There were no significant differences regarding GW and FE between husbandry clusters, due to the large variability within clusters regarding feed composition and conversion. Therefore, both husbandry aspects associated with improved animal welfare have a significant influence on some environmental impacts, such as acidification and marine eutrophication. Nevertheless, the large variation within clusters suggests that trade-offs may be minimised through e.g. AC and ME.

Substitution modeling can coherently be used in attributional life cycle assessments

AbstractMost life cycle assessment (LCA) studies use the attributional methodology. This approach attributes a share of global environmental impacts to one or multiple functions provided by a normatively circumscribed system. Multifunctional systems that are not technologically subdivisible between co‐functions are frequently encountered in LCA studies. It then becomes necessary to resort to co‐production modeling techniques, like the substitution approach. The use of substitution modeling in attributional LCA (ALCA) is, however, discouraged amongst practitioners, due to the alleged violation of central requirements of the attributional methodology. The objective of this research is to shed light on common misconceptions about the compatibility of substitution with ALCA. The first misconception is that the use of substitution in ALCA violates the conservation of total environmental impacts. We find that this idea arises from a confusion regarding the attribution of impacts to the secondary product(s). The second misconception stipulates that substitution is not coherent with the state‐descriptive characteristic of ALCA. We conclude that we can describe a given system as resulting from an inferred (substitution) change, rather than as disrupted by this change. Finally, we discuss the choice of the substituted technology, and argue there is a logic to marginal substitution in ALCA. We therefore recommend accepting substitution modeling in ALCA.

Method for Calculating the Avoided Impact of Specific Information and Communication Technology Services

Particular Information and Communication Technology (ICT) services can help avoid environmental impact in larger contexts. However, there is no commonly agreed bottom-up methodology for calculation of the total net reduction effect of specific digital ICT services. Life Cycle Assessment (LCA) is a common denominator for most methodologies. The most common method is the Attributional LCA (ALCA), and recently the emerging handprint ALCA estimating so-called positive environmental impacts. Moreover, Consequential LCA (CLCA) can be used to capture market effects. The third conceptual approach is Input-Output LCA. The purpose is to propose and test a new method based on some of the existing ones. The existing concepts are compared and a synthesis is made to create a practical but still useful method. The new method is applied to two illustrative cases in the ICT domain; the introduction of a 5G enabled drone for pipe inspection and the 5G enabled health consultation. Compared to simplified ALCA, the difference between the absolute scores for the baseline system and the target system changes around 10% when the proposed simplified CLCA (SCLCA) method is used. The results show that SCLCA, when combined with analytical methods for expressing digital ICT services’ own impact, is a fruitful approach which is both practical and feasible. The new method includes formulae for calculating the total lifetime environmental impact of a specific ICT Equipment when reused or replaced.

Advancing Biodiesel Production System from Mixed Vegetable Oil Waste: A Life Cycle Assessment of Environmental and Economic Outcomes

This study aims to evaluate the environmental and economic performance of biodiesel production from mixed vegetable oil waste using the life cycle assessment (LCA) model. Due to its huge potential, Pakistan is taken as a case study. It produces 468,842 tons of vegetable oil waste annually. As no biodiesel production plant exists to process it, the environmental performance of biodiesel prototypes has not been investigated. Therefore, the current study is conducted to support the design of a plant to produce biodiesel from mixed oil waste. An attributional LCA was conducted using ReCiPe (H) and found that 400 kg of biodiesel can be produced from 1 t of mixed oil waste. The results, based on a functional unit of 1 ton, showed that biodiesel production from mixed vegetable oil waste is more eco-friendly than the existing landfilling practices with a global warming potential of 1.36 × 10−4 kg CO2 eq, human toxicity of 5.31 kg 1.4 DB eq, ozone depletion potential of 0.00271 kg CFC-11 eq, eutrophication potential of 0.0118 kg P eq, acidification potential of 123 kg SO2 eq, and photochemical ozone formation of 51.4 kg NOx eq. Scenario modelling was conducted using electricity from photovoltaic solar cells, which decrease fine particulate matter formation from 44.5 to 0.725 kg PM2.5 eq, instead of using electricity from a grid to the plant. Hotspot identification was carried out to highlight the effects of individual impact categories. An economic analysis showed that 638,839 USD/year revenue would be generated. Generating energy from discarded vegetable oils through biodiesel production presents a sustainable and economically viable approach. This process benefits the environment and contributes to cost savings by reducing waste disposal in landfills. Furthermore, it aligns with the principles of a circular economy, in which resources are reused and recycled. It also supports the pursuit of the United Nations’ Sustainable Development Goals (SDGs), particularly SDG-7, which focuses on affordable and clean energy, and SDG-12, which emphasizes responsible consumption and production.

Increasing temporal resolution in greenhouse gas accounting of electricity consumption divided into Scopes 2 and 3: case study of Germany

PurposeAs renewable energy sources (RES) experience short-term variability, electricity greenhouse gas (GHG) emissions also fluctuate. Increasing temporal resolution in electricity emissions accounting allows capturing these fluctuations. However, existing time-resolved models either neglect indirect impacts, adopt a generation perspective, or are based on non-public country-specific data. We provide an approach for calculating time-resolved GHG emission factors (EFs) of electricity consumption based on open access data for European countries and examine the temporal variability of German EFs.MethodsTime-resolved electricity GHG EFs are calculated within the framework of attributional life cycle assessment (LCA) with up to quarter-hourly resolution. The approach involves top-down calculation of annual combustion emissions, validation and scaling of time-resolved electricity generation data, as well as calculation of inland consumption EFs for each interval throughout a year. The EFs are divided by the stages of net generation, consumption by hydro-pumped storage (HPS), and transmission and distribution (T&D) losses, as well as Scopes 2 and 3, enabling GHG Protocol Corporate Standard-compliant reporting. The approach is exemplarily applied to Germany and its transmission system operator zones at quarter-hourly resolution for the years from 2017 to 2020 to investigate the relation between grid mix composition and temporal variability of EFs.Results and discussionThe annual average EF of the German consumption mix, encompassing direct and upstream emissions, declined from 499 (2017) to 377 g CO2e/kWh (2020), while quarter-hourly variability increased by 12%. Neglecting upstream emissions and intermediate steps between generation and consumption in Germany in 2020 resulted in an underestimation of 13% on an annual level, while quarter-hourly Scope 3 EFs reached up to 100 g CO2e/kWh. On a sub-national level, annual average EFs varied between 157 g CO2e/kWh (TenneT zone) and 505 g CO2e/kWh (50Hertz zone) in 2020. Temporal variability is the greatest in electricity systems with both fossil-fuel and renewable capacity sufficient to dominate short-term electricity generation. At an advanced level of RES integration, the fluctuations of EFs start declining, as demonstrated by the TenneT case.ConclusionAn increased temporal resolution in electricity emissions accounting can enhance a posteriori LCA results’ accuracy during the energy transition phase. The provided EFs link the life cycle-based perspective with time-resolved emissions accounting. With increasing reliance on RES, indirect emissions, including those related to energy storage, will gain in significance. The next step should focus on integrating physical cross-border electricity exchanges to complete the consumption perspective, as well as examining practical implementation to other countries.