Global decarbonization potential of CO2 mineralization in concrete materials.

CO2 mineralization products are often heralded as having outstanding potentials to reduce CO2-eq. emissions. However, these claims are generally undermined by incomplete consideration of the life cycle climate change impacts, material properties, supply and demand constraints, and economic viability of CO2 mineralization products. We investigate these factors in detail for ten concrete-related CO2 mineralization products to quantify their individual and global CO2-eq. emissions reduction potentials. Our results show that in 2020, 3.9 Gt of carbonatable solid materials were generated globally, with the dominant material being end-of-life cement paste in concrete and mortar (1.4 Gt y-1). All ten of the CO2 mineralization technologies investigated here reduce life cycle CO2-eq. emissions when used to substitute comparable conventional products. In 2020, the global CO2-eq. emissions reduction potential of economically competitive CO2 mineralization technologies was 0.39 Gt CO2-eq., i.e., 15% of that from cement production. This level of CO2-eq. emissions reduction is limited by the supply of end-of-life cement paste. The results also show that it is 2 to 5 times cheaper to reduce CO2-eq. emissions by producing cement from carbonated end-of-life cement paste than carbon capture and storage (CCS), demonstrating its superior decarbonization potential. On the other hand, it is currently much more expensive to reduce CO2-eq. emissions using some CO2 mineralization technologies, like carbonated normal weight aggregate production, than CCS. Technologies and policies that increase recovery of end-of-life cement paste from aged infrastructure are key to unlocking the potential of CO2 mineralization in reducing the CO2-eq. footprint of concrete materials.

Carbon reduction and water saving potentials for growing corrugated boxes for express delivery services in China.

Corrugated packaging for express grew by 90 times to 16.5 Mt y-1 in China, where 81% of recent global express delivery growth occurred. However, the environmental impacts of production, usage, disposal, and recycling of corrugated boxes under the entire supply chain remain unclear. Here, we estimate the magnitudes, drivers, and mitigation potentials of cradle-to-grave life-cycle carbon footprint (CF) and three colors of water footprints (WFs) for corrugated cardboard packaging in China. Over 2007 to 2021, CF, blue and gray WFs per unit package decreased by 45%, 60%, and 84%, respectively, while green WF increased by 23% with growing imports of virgin pulp and China's waste ban. National total CF and WFs were 21 to 102 folded with the scale effects. Only a combination of the supply chain reconstruction, lighter single-piece packaging, and increased recycling rate can possibly reduce the environmental footprints by 24 to 44% by 2035.

Complementary roles for mechanical and solvent-based recycling in low-carbon, circular polypropylene.

Plastic recycling presents a vexing challenge. Mechanical recycling offers substantial greenhouse gas emissions savings relative to virgin plastic production but suffers from degraded aesthetic and mechanical properties. Polypropylene, one of the most widely used and lowest-cost plastics, features methyl pendants along the polymer backbone, rendering it particularly susceptible to declining properties, performance, and aesthetics across a succession of mechanical recycles. Advanced processes, such as solvent-assisted recycling, promise near-virgin quality outputs at a greater energy and emissions footprint. Mechanical and advanced recycling are often presented as competing options, but real-world plastic waste streams are likely to require preprocessing regardless of whether they are routed to an advanced process. This study quantifies the life-cycle greenhouse gas implications of multiple recycling strategies and proposes a system in which mechanical and solvent-assisted recycling can be leveraged together to boost recycling rates and satisfy demand for a wider range of product applications. Polypropylene can be recovered from mixed-plastic bales produced at material recovery facilities and processed through mechanical recycling, with a varying fraction sent for further upgrading via solvent-assisted recycling to produce material approved for food packaging and other higher-quality applications. The resulting mechanically recycled rigid polypropylene reduces life-cycle greenhouse gas emissions by 80% relative to the same quantity of virgin material, while the upgraded higher-quality material achieves GHG savings of 30%.

Evolving assessment pathways for precision oncology medicines to improve patient access: a tumor-agnostic lens.

BACKGROUND: Genomic and molecular alterations are increasingly important in cancer diagnosis, and scientific advances are opening new treatment avenues. Precision oncology (PO) uses a patient's genomic profile to determine optimal treatment, promising fewer side effects and higher success rates. Within PO, tumor-agnostic (TA) therapies target genomic alterations irrespective of tumor location. However, traditional value frameworks and approval pathways pose challenges which may limit patient access to PO therapies. OBJECTIVES: This study describes challenges in assessing PO and TA medicines, explores possible solutions, and provides actionable recommendations to facilitate an iterative life-cycle assessment of these medicines. METHODS: After reviewing the published literature, we obtained insights from key stakeholders and European experts across a range of disciplines, through individual interviews and an industry workshop. The research was guided and refined by an international expert committee through 2 sounding board meetings. RESULTS: The current challenges faced by PO and TA medicines are multiple and can be demonstrated through real-world examples of the current barriers and opportunities. A life-cycle approach to assessment should be taken, including key actions at the early stages of evidence generation, regulatory and reimbursement stage, as well as payment and adoption solutions that make use of the evolving evidence base. Working toward these solutions to maximize PO medicine value is a shared responsibility and stands to benefit all stakeholders. CONCLUSIONS: Our call to action is to expand access to comprehensive genomic testing, foster a learning health care system, enable fast and equitable access to cost-effective treatments, and ultimately improve health outcomes.

Bayesian Optimization of Environmentally Sustainable Graphene Inks Produced by Wet Jet Milling.

Liquid phase exfoliation (LPE) of graphene is a potentially scalable method to produce conductive graphene inks for printed electronic applications. Among LPE methods, wet jet milling (WJM) is an emerging approach that uses high-speed, turbulent flow to exfoliate graphene nanoplatelets from graphite in a continuous flow manner. Unlike prior WJM work based on toxic, high-boiling-point solvents such as n-methyl-2-pyrollidone (NMP), this study uses the environmentally friendly solvent ethanol and the polymer stabilizer ethyl cellulose (EC). Bayesian optimization and iterative batch sampling are employed to guide the exploration of the experimental phase space (namely, concentrations of graphite and EC in ethanol) in order to identify the Pareto frontier that simultaneously optimizes three performance criteria (graphene yield, conversion rate, and film conductivity). This data-driven strategy identifies vastly different optimal WJM conditions compared to literature precedent, including an optimal loading of 15 wt% graphite in ethanol compared to 1 wt% graphite in NMP. These WJM conditions provide superlative graphene production rates of 3.2 g hr-1 with the resulting graphene nanoplatelets being suitable for screen-printed micro-supercapacitors. Finally, life cycle assessment reveals that ethanol-based WJM graphene exfoliation presents distinct environmental sustainability advantages for greenhouse gas emissions, fossil fuel consumption, and toxicity.

What is the environmental impact of a blood transfusion? A life cycle assessment of transfusion services across England.

BACKGROUND: Healthcare activities significantly contribute to greenhouse gas (GHG) emissions. Blood transfusions require complex, interlinked processes to collect, manufacture, and supply. Their contribution to healthcare emissions and avenues for mitigation is unknown. STUDY DESIGN AND METHODS: We performed a life cycle assessment (LCA) for red blood cell (RBC) transfusions across England where 1.36 million units are transfused annually. We defined the process flow with seven categories: donation, transportation, manufacturing, testing, stockholding, hospital transfusion, and disposal. We used direct measurements, manufacturer data, bioengineering databases, and surveys to assess electrical power usage, embodied carbon in disposable materials and reagents, and direct emissions through transportation, refrigerant leakage, and disposal. RESULTS: The central estimate of carbon footprint per unit of RBC transfused was 7.56 kg CO2 equivalent (CO2eq). The largest contribution was from transportation (2.8 kg CO2eq, 36% of total). The second largest was from hospital transfusion processes (1.9 kg CO2eq, 26%), driven mostly by refrigeration. The third largest was donation (1.3 kg CO2eq, 17%) due to the plastic blood packs. Total emissions from RBC transfusion are ~10.3 million kg CO2eq/year. DISCUSSION: This is the first study to estimate GHG emissions attributable to RBC transfusion, quantifying the contributions of each stage of the process. Primary areas for mitigation may include electric vehicles for the blood service fleet, improving the energy efficiency of refrigeration, using renewable sources of electricity, changing the plastic of blood packs, and using methods of disposal other than incineration.

Country-Specific External Costs of Abiotic Resource Use Based on User Cost Model in Life Cycle Impact Assessment.

Abiotic resources are indispensable in society, but there are concerns regarding their depletion, scarcity, and increasing prices, resulting in potential economic damage in the future. To address these concerns, it is effective to consider the external costs of resource use. Although resource availability is different among mining sites, and local conditions are relevant in assessing resource scarcity, previous studies have assessed external costs and potential impacts of abiotic resource use globally. This study provides country-specific characterization factors (CFs) of abiotic resource use in life cycle impact assessment based on the user cost model, which represents the external costs of abiotic resource use to reflect country-specific resource scarcity. We demonstrate considerable variations in the CFs depending on the mining country, suggesting that the choice of mining country can affect external costs. The global external cost of abiotic resource use in 2020 was estimated at 1.9 trillion $, with a major contribution from the extraction of fossil fuels in the United States. Historical trends of the CFs and relevant parameters showed temporal fluctuations, emphasizing the importance of regularly updating the data underlying the calculation of the CFs. Country-level assessments of the external costs of resource use can contribute to discussions on the responsibilities of consuming countries by incorporating material footprint studies.

Meta-ecosystem Frameworks Can Enhance Control of the Biotic Transport of Microplastics.

The lack of systematic approaches and analyses to identify, quantify, and manage the biotic transport of microplastics (MPs) along cross-ecosystem landscapes prevents the current goals of sustainable environmental development from being met. This Perspective proposes a meta-ecosystem framework, which considers organismal and resource flows among ecosystems to shed light on the research and management challenges related to both abiotic and biotic MP transport at landscape levels. We discuss MP transport pathways through species movements and trophic transfers among ecosystems and sub-ecosystems, and highlight these pathways in the mitigation of MP pollution. The integration of biotic pathways across landscapes prioritizes management actions for MP transport using diverse approaches such as wastewater treatment and plastic removal policies to mitigate contamination. In addition, our framework emphasizes the potential sink enhancement of MPs through habitat conservation and enhancement of riparian vegetation. By considering the mechanisms of meta-ecosystem dynamics through the processes of biotic dispersal, accumulation, and the ultimate fate of MPs, advances in the environmental impact assessment and management of MP production can proceed more effectively.

Regulation Mechanism for Designing Decarbonization Pathways in the Copper Industry Toward Carbon Neutrality.

The transformation of the global power structure caused by the carbon neutrality goal will promote copper consumption. It is crucial to explore the decarbonization pathways of the copper industry to help fulfill greenhouse gas (GHG) emission reduction targets. This study utilized material flow analysis and life cycle assessment methods to investigate 12 different subscenarios based on international trade, circular economy, technology evolution, and environmental market factors. Policy combination scenario is employed to reveal the mechanism of decarbonization. The results show that refined copper consumption in China is expected to increase by 62.3% in 2060 compared to 2020. The GHG emissions of China's copper industry will reach 9.1 million tonnes (Mt) CO2e in 2060, technology evolution and environmental market are crucial for realizing carbon neutrality goal of this industry, accounting for 26.4 and 47.2% of emissions reductions, respectively, between 2020 and 2060. International trade and circular economy play important roles in the high-quality carbon peaking stage; however, imported copper and domestic secondary copper will constitute the basic supply of copper resources in China in the long run, and the comparative advantages of them will gradually weaken. Policy combination scenario can achieve the incentive synergy effect, with GHG reduced to 0.5 Mt CO2e in 2060. The enhanced application of policies such as material substitution and carbon emission trading will further promote industry to achieve net-zero GHG emission. We suggest regulating the industry's structure based on the international systemic circulation pattern and accelerating the construction of a green circular chain in the short term to achieve sustainable copper supply and high-quality carbon peaking. Promoting a high-quality technology development strategy and enhancing the environmental markets are recommended in the long term to achieve carbon neutrality.

Toward Low-Carbon Rice Production in China: Historical Changes, Driving Factors, and Mitigation Potential.

Under the "Double Carbon" target, the development of low-carbon agriculture requires a holistic comprehension of spatially and temporally explicit greenhouse gas (GHG) emissions associated with agricultural products. However, the lack of systematic evaluation at a fine scale presents considerable challenges in guiding localized strategies for mitigating GHG emissions from crop production. Here, we analyzed the county-level carbon footprint (CF) of China's rice production from 2007 to 2018 by coupling life cycle assessment and the DNDC model. Results revealed a significant annual increase of 74.3 kg CO2-eq ha-1 in the average farm-based CF (FCF), while it remained stable for the product-based CF (PCF). The CF exhibited considerable variations among counties, ranging from 2324 to 20,768 kg CO2-eq ha-1 for FCF and from 0.36 to 3.81 kg CO2-eq kg-1 for PCF in 2018. The spatiotemporal heterogeneities of FCF were predominantly influenced by field CH4 emissions, followed by diesel consumption and soil organic carbon sequestration. Scenario analysis elucidates that the national total GHG emissions from rice production could be significantly reduced through optimized irrigation (48.5%) and straw-based biogas production (18.0%). Moreover, integrating additional strategies (e.g., advanced crop management, optimized fertilization, and biodiesel application) could amplify the overall emission reduction to 76.7% while concurrently boosting the rice yield by 11.8%. Our county-level research provides valuable insights for the formulation of targeted GHG mitigation policies in rice production, thereby advancing the pursuit of carbon-neutral agricultural practices.

Prioritizing Organic Pollutants for Shale Gas Exploitation: Life Cycle Environmental Risk Assessments in China and the US.

Environmental impacts associated with shale gas exploitation have been historically underestimated due to neglecting to account for the production or the release of end-of-pipe organic pollutants. Here, we assessed the environmental impacts of shale gas production in China and the United States using life cycle assessment. Through data mining, we compiled literature information on organic pollutants in flowback and produced water (FPW), followed by assessments using USEtox to evaluate end-of-pipe risks. Results were incorporated to reveal the life cycle risks associated with shale gas exploitation in both countries. China exhibited higher environmental impacts than the US during the production phase. Substantially different types of organic compounds were observed in the FPW between two countries. Human carcinogenic and ecological toxicity attributed to organics in FPW was 3 orders of magnitude higher than that during the production phase in the US. Conversely, in China, end-of-pipe organics accounted for approximately 52%, 1%, and 47% of the overall human carcinogenic, noncarcinogenic, and ecological impacts, respectively. This may be partially limited by the quantitative data available. While uncertainties exist associated with data availability, our study highlights the significance of integrating impacts from shale gas production to end-of-pipe pollution for comprehensive environmental risk assessments.

Life Cycle Economic and Environmental Assessment of Producing Synthetic Jet Fuel Using CO2/Biomass Feedstocks.

The aviation industry is responsible for over 2% of global CO2 emissions. Synthetic jet fuels generated from biogenic feedstocks could help reduce life cycle greenhouse gas (GHG) emissions compared to petroleum-based fuels. This study assesses three processes for producing synthetic jet fuel via the synthesis of methanol using water and atmospheric CO2 or biomass. A life cycle assessment and cost analysis are conducted to determine GHG emissions, energy demand, land occupation, water depletion, and the cost of producing synthetic jet fuel in Switzerland. The results reveal that the pathway that directly hydrogenates CO2 to methanol exhibits the largest reductions in terms of GHG emission (almost 50%) compared to conventional jet fuel and the lowest production cost (7.86 EUR kgJF-1); however, its production cost is currently around 7 times higher than the petroleum-based counterpart. Electrical energy was found to be crucial in capturing CO2 and converting water into hydrogen, with the sourcing and processing of the feedstocks contributing to 79% of the electric energy demand. Furthermore, significant variations in synthetic jet fuel cost and GHG emissions were shown when the electricity source varies, such as utilizing grid electricity pertaining to different countries with distinct electricity mixes. Thus, upscaling synthetic jet fuels requires energy-efficient supply chains, sufficient feedstock, large amounts of additional (very) low-carbon energy capacity, suitable climate policy, and comprehensive environmental analyses.

Replacing Plastics with Alternatives Is Worse for Greenhouse Gas Emissions in Most Cases.

Plastics are controversial due to their production from fossil fuels, emissions during production and disposal, potential toxicity, and leakage to the environment. In light of these concerns, calls to use less plastic products and move toward nonplastic alternatives are common. However, these calls often overlook the environmental impacts of alternative materials. This article examines the greenhouse gas (GHG) emission impact of plastic products versus their alternatives. We assess 16 applications where plastics are used across five key sectors: packaging, building and construction, automotive, textiles, and consumer durables. These sectors account for about 90% of the global plastic volume. Our results show that in 15 of the 16 applications a plastic product incurs fewer GHG emissions than their alternatives. In these applications, plastic products release 10% to 90% fewer emissions across the product life cycle. Furthermore, in some applications, such as food packaging, no suitable alternatives to plastics exist. These results demonstrate that care must be taken when formulating policies or interventions to reduce plastic use so that we do not inadvertently drive a shift to nonplastic alternatives with higher GHG emissions. For most plastic products, increasing the efficiency of plastic use, extending the lifetime, boosting recycling rates, and improving waste collection would be more effective for reducing emissions.

A Novel Sustainable and Self-Sufficient Biotechnological Strategy for Directly Transforming Sewage Sludge into High-Value Liquid Biochemicals.

Sewage sludge, as a carbon-rich byproduct of wastewater treatment, holds significant untapped potential as a renewable resource. Upcycling this troublesome waste stream represents great promise in addressing global escalating energy demands through its wide practice of biochemical recovery concurrently. Here, we propose a biotechnological concept to gain value-added liquid bioproducts from sewage sludge in a self-sufficient manner by directly transforming sludge into medium-chain fatty acids (MCFAs). Our findings suggest that yeast, a cheap and readily available commercial powder, would involve ethanol-type fermentation in chain elongation to achieve abundant MCFA production from sewage sludge using electron donors (i.e., ethanol) and acceptors (i.e., short-chain fatty acids) produced in situ. The enhanced abundance and transcriptional activity of genes related to key enzymes, such as butyryl-CoA dehydrogenase and alcohol dehydrogenase, affirm the robust capacity for the self-sustained production of MCFAs. This is indicative of an effective metabolic network established between yeast and anaerobic microorganisms within this innovative sludge fermentation framework. Furthermore, life cycle assessment and techno-economic analysis evidence the sustainability and economic competitiveness of this biotechnological strategy. Overall, this work provides insights into sewage sludge upgrading independent of additional carbon input, which can be applied in existing anaerobic sludge fermentation infrastructure as well as to develop new applications in a diverse range of industries.

National Greenhouse Gas Emission Reduction Potential from Adopting Anaerobic Digestion on Large-Scale Dairy Farms in the United States.

Waste-to-energy systems can provide a functional demonstration of the economic and environmental benefits of circularity, innovation, and reimagining existing systems. This study offers a robust quantification of the greenhouse gas (GHG) emission reduction potential of the adoption of anaerobic digestion (AD) technology on applicable large-scale dairy farms in the contiguous United States. GHG reduction estimates were developed through a robust life cycle modeling framework paired with sensitivity and uncertainty analyses. Twenty dairy configurations were modeled to capture important differences in housing and manure management practices, applicable AD technologies, regional climates, storage cleanout schedules, and methods of land application. Monte Carlo results for the 90% confidence interval illustrate the potential for AD adoption to reduce GHG emissions from the large-scale dairy industry by 2.45-3.52 MMT of CO2-eq per year considering biogas use only in renewable natural gas programs and as much as 4.53-6.46 MMT of CO2-eq per year with combined heat and power as an additional biogas use case. At the farm level, AD technology may reduce GHG emissions from manure management systems by 58.1-79.8% depending on the region. Discussion focuses on regional differences in GHG emissions from manure management strategies and the challenges and opportunities surrounding AD adoption.

Quorum Quenching in Membrane Bioreactors for Fouling Retardation: Complexity Provides Opportunities.

The occurrence of biofouling restricts the widespread application of membrane bioreactors (MBRs) in wastewater treatment. Regulation of quorum sensing (QS) is a promising approach to control biofouling in MBRs, yet the underlying mechanisms are complex and remain to be illustrated. A fundamental understanding of the relationship between QS and membrane biofouling in MBRs is lacking, which hampers the development and application of quorum quenching (QQ) techniques in MBRs (QQMBRs). While many QQ microorganisms have been isolated thus far, critical criteria for selecting desirable QQ microorganisms are still missing. Furthermore, there are inconsistent results regarding the QQ lifecycle and the effects of QQ on the physicochemical characteristics and microbial communities of the mixed liquor and biofouling assemblages in QQMBRs, which might result in unreliable and inefficient QQ applications. This review aims to comprehensively summarize timely QQ research and highlight the important yet often ignored perspectives of QQ for biofouling control in MBRs. We consider what this "information" can and cannot tell us and explore its values in addressing specific and important questions in QQMBRs. Herein, we first examine current analytical methods of QS signals and discuss the critical roles of QS in fouling-forming microorganisms in MBRs, which are the cornerstones for the development of QQ technologies. To achieve targeting QQ strategies in MBRs, we propose the substrate specificity and degradation capability of isolated QQ microorganisms and the surface area and pore structures of QQ media as the critical criteria to select desirable functional microbes and media, respectively. To validate the biofouling retardation efficiency, we further specify the QQ effects on the physicochemical properties, microbial community composition, and succession of mixed liquor and biofouling assemblages in MBRs. Finally, we provide scale-up considerations of QQMBRs in terms of the debated QQ lifecycle, practical synergistic strategies, and the potential cost savings of MBRs. This review presents the limitations of classic QS/QQ hypotheses in MBRs, advances the understanding of the role of QS/QQ in biofouling development/retardation in MBRs, and builds a bridge between the fundamental understandings and practical applications of QQ technology.

Solar-Powered Direct Air Capture: Techno-Economic and Environmental Assessment.

Direct air capture (DAC) of CO2 has gained attention as a sustainable carbon source. One of the most promising technologies currently available is liquid solvent DAC (L-DAC), but the significant fraction of fossil CO2 in the output stream hinders its utilization in carbon-neutral fuels and chemicals. Fossil CO2 is generated and captured during the combustion of fuels to calcine carbonates, which is difficult to decarbonize due to the high temperatures required. Solar thermal energy can provide green high-temperature heat, but it flourishes in arid regions where environmental conditions are typically unfavorable for L-DAC. This study proposes a solar-powered L-DAC approach and develops a model to assess the influence of the location and plant capacity on capture costs. The performed life cycle assessment enables the comparison of technologies based on net CO2 removal, demonstrating that solar-powered L-DAC is not only more environmentally friendly but also more cost-effective than conventional L-DAC.

Temperature-Pressure Swing Process for Reactive Carbon Capture and Conversion to Methanol: Techno-Economic Analysis and Life Cycle Assessment.

A model was developed to conduct techno-economic analysis (TEA) and life cycle assessment (LCA) for reactive carbon capture (RCC) and conversion of carbon dioxide (CO2) to methanol. This RCC process is compared to a baseline commercialized flue gas CO2 hydrogenation process. An ASPEN model was combined with existing TEA and LCA models into a larger TEA/LCA framework in Python. From preliminary experimental data, the model found a levelized cost of $0.79/kg methanol for the baseline process and $0.99/kg for the RCC process. The cradle-to-gate carbon intensity of the baseline process was 0.50 kg-CO2e/kg-methanol, compared to 0.55 kg-CO2e/kg-methanol for the RCC process. However, water consumption for RCC (10.21 kg-H2O/kg-methanol) is greatly reduced compared to the baseline (12.89 kg-H2O/kg-methanol). Future improvements in hydrogen electrolysis costs will benefit the RCC. A target H2/methanol mass ratio of 0.26 was developed for RCC laboratory experiments to reduce methanol cost below the baseline. If a ratio of 0.24 can be achieved, a levelized cost of $0.76/kg methanol is projected, with a carbon intensity of 0.42 kg-CO2e/kg-methanol.

Impacts of Behavioral, Organizational, and Spatial Factors on the Carbon Footprint of Traditional Retail and E-commerce in the Paris Region.

Carbon footprint assessment of retail is necessary to optimize procurement strategies and adopt sustainable shopping habits. However, estimating carbon footprints is a complex task, given the diversity of existing distribution channels. Average values for carbon emissions of "conventional" retail (i.e., purchasing and receiving the product directly at the physical point of sale) found in most studies mask a heterogeneous reality: different retail strategies entail diverse shopping behavior for consumers, as well as varied procurement processes for outlets. In this paper, we propose a methodology to assess greenhouse gas (GHG) impacts of different distribution systems related to the consumption of goods in the Paris Region by coupling traditional transport modeling with a life-cycle assessment (LCA) approach. We model and compare six distribution systems, including five traditional retail formats (hypermarkets, supermarkets, small generalist retail, small food retail, and small nonfood retail) and E-commerce home deliveries. Our model includes warehouse activity, shop and home delivery, shop energy consumption, consumer mobility, and goods packaging. Overall, we conclude that E-commerce emits fewer GHG emissions than retail outlets per kilogram of product purchased. This result is in line with the existing literature on the topic. However, the carbon footprint varies greatly within the case study depending on the characteristics of the logistics procurement processes of outlets, the behavior of shoppers, and spatial characteristics.

Combining Fleetwide AviTeam Aviation Emission Modeling with LCA Perspectives for an Alternative Fuel Impact Assessment.

Reducing aviation emissions is important as they contribute to air pollution and climate change. Several alternative aviation fuels that may reduce life cycle emissions have been proposed. Comparative life cycle assessments (LCAs) of fuels are useful for inspecting individual fuels, but systemwide analysis remains difficult. Thus, systematic properties like fleet composition, performance, or emissions and changes to them under alternative fuels can only be partially addressed in LCAs. By integrating the geospatial fuel and emission model, AviTeam, with LCA, we can assess the mitigation potential of a fleetwide use of alternative aviation fuels on 210 000 shorter haul flights. In an optimistic case, liquid hydrogen (LH2) and power-to-liquid fuels, when produced with renewable electricity, may reduce emissions by about 950 GgCO2eq when assessed with the GWP100 metric and including non-CO2 impacts for all flights considered. Mitigation potentials range from 44% on shorter flights to 56% on longer flights. Alternative aviation fuels' mitigation potential is limited because of short-lived climate forcings and additional fuel demand to accommodate LH2 fuel. Our results highlight the importance of integrating system models into LCAs and are of value to researchers and decision-makers engaged in climate change mitigation in the aviation and transport sectors.