Search Results (9,136)

Environmental sustainability of natural and synthetic fibers used in textiles and composites depends on their impacts throughout production, use, and end-of-life (EoL) stages. Natural fibers are renewable and biodegradable but may require substantial water and agricultural inputs, whereas synthetic fibers contribute to fossil resource depletion, microplastic pollution, and persistent waste generation. Natural fibers are often regarded as more sustainable alternatives to synthetic fiber; however, evidence from a life cycle assessment (LCA) reveals a more nuanced reality. As demand for fiber-based materials increases across textile and composite applications, a deeper understanding of the environmental implications of both natural and synthetic options becomes essential. This review compares these fiber categories from a life cycle perspective, examining carbon footprint, energy demands, resource consumption, and EoL pathways. Natural fibers such as cotton, flax, jute, hemp, sisal, banana, coir, and emerging plant-based alternatives offer advantages including biodegradability and carbon sequestration during cultivation. Nevertheless, agricultural practices and subsequent industrial processing require substantial land, water, and chemical inputs. Synthetic fibers, predominantly derived from fossil resources, provide a long service life and consistent performance but are associated with high greenhouse gas (GHG) emissions, dependence on non-renewable feedstocks, microplastic pollution, and broader environmental impacts. By presenting a comprehensive life cycle-based comparison, this review identifies the conditions under which each fiber type may offer environmental benefits, supporting informed material selection for sustainable development. Full article

Road transport is a major contributor to greenhouse gas (GHG) emissions, representing a significant challenge when it comes to achieving climate goals. Although methodologies such as Activity–Structure–Intensity–Fuel (ASIF) are widely used to estimate transport emissions, their application as regulatory instruments remains unexplored. This study addresses this gap by proposing a framework that operationalizes ASIF for managing Scope 3 emissions in toll-road concessions. Using operational and traffic data from a major Brazilian highway concession, baseline emissions are compared with intervention scenarios involving the adoption of initiatives such as free-flow tolling and fleet electrification. The results demonstrate that emission reductions can be associated with specific ASIF components and can be translated into measurable contractual indicators. In the case study, the implementation of free-flow tolling reduced emissions at toll plazas by up to 37%. Fleet electrification, which is now limited by the charging capacity of roads, can be improved and have its effects captured by the framework so that actions resulting from the concessions made to improve availability can enable policies aimed at reducing total user-related emissions. The study is the first, to the best of the authors’ knowledge, to operationalize the ASIF methodology as a governance and contractual instrument for Scope 3 emissions management in highway concessions in Brazil. By bridging emissions estimation and concession governance, it provides a practical framework for incorporating Scope 3 mitigation targets into concession contracts and climate-oriented transport regulation. Full article

The production of hot mix asphalt (HMA) is energy-intensive, resulting in carbon dioxide (CO₂) and greenhouse gas (GHG) emissions. The primary energy source (accounting for over 97%) and emissions source is the rotary drum employed for the drying and heating of the aggregates. Quantifying the CO₂ emissions associated with combustion is of crucial importance in order to facilitate a more profound comprehension of the environmental impacts of HMA production. The objectives of this study are to develop a methodological framework for the quantification of combustion-related carbon dioxide emissions in the context of asphalt production. The proposed framework investigates three complementary approaches: (i) an energy-balance-based thermal energy (TE) model, (ii) recordings of fuel consumption and (iii) direct measurement of exhaust-gas composition. By applying these methods in parallel and cross-comparing their results batch by batch, the framework enables reliable verification of actual CO₂ emissions from the module A3—production stage of asphalt manufacturing. In this stage, the predominant source of greenhouse gases is fuel combustion during aggregate drying and heating. A comprehensive set of data was collected from two HMA batch plants, each operating under distinct conditions. The parameters considered included fuel type, asphalt mixture type, asphalt production time, aggregate moisture content, mixing temperature, and production rate. The TE model demonstrated a robust linear correlation with measured energy consumption (R² = 0.97), and fuel-based CO₂ estimates exhibited minimal discrepancy compared to direct exhaust-gas measurements on average (mean difference 1.0%; t-test p = 0.674). However, systematic discrepancies were observed between the two plants (with overestimation of up to 20% at one plant (AP1) and underestimation of up to 12% at the other (AP2)). This demonstrates that energy-based CO₂ estimation methods require plant-specific calibration against direct measurement before they can be reliably applied in life cycle assessment (LCA) and environmental product declaration (EPD) practice. Measured CO₂ emission intensities ranged from 17.39 to 21.76 kg/t at AP1 and from 16.05 to 18.44 kg/t at AP2; the casing-losses factor of the TE model was calibrated to CL = 23% for the studied diesel-fired plants (mean deviation +0.4% from measured energy); and aggregate moisture content explained 74% of the variance in measured energy consumption (R² = 0.743). Full article

The electrocatalytic reduction of CO₂ into value-added chemicals offers a promising route to mitigate greenhouse gas emissions, yet the uncontrollable structural reconstruction and surface rearrangement of electrocatalysts during operation often lead to severe activity degradation. Herein, we reveal that Bi₂O₂SO₄ (BSO) undergoes an irreversible phase transformation into Bi₂O₂CO₃ (BCO) nanosheets accompanied by the partial reduction of Bi³⁺ to metallic Bi⁰ under cathodic potentials. A series of BCO/BSO heterojunction catalysts with tunable compositions are synthesized via a mild in situ ion-exchange method. To circumvent the detrimental effects of this dynamic reconstruction, we devise a pre-activation strategy that deliberately completes the structural evolution prior to electrocatalysis. The optimized 20%-BCO/BSO heterojunction achieves a remarkable Faradaic efficiency of 98.4% for formate production in a flow cell at elevated potentials, with >95% FE_(HCOOH) over a wide potential window (−0.8 to −1.7 V vs. RHE). In situ infrared spectroscopy elucidates that the reconstructed interface can promote CO₂ adsorption, stabilize the *OCHO intermediate, and facilitate HCOOH desorption. This work provides experimental evidence of the reconstruction behaviour of bismuth-based catalysts and offers a rational design method for constructing structurally stable heterojunction electrocatalysts. Full article

The transport sector contributes nearly 20% of New Zealand’s total greenhouse gas emissions, making it crucial for interventions to meet the 2050 net-zero target. Transitioning to electric vehicles (EVs) presents a sustainable solution but poses challenges in electricity distribution due to unpredictable EV charging behaviours. This research addresses these challenges by developing three mathematical models that optimise EV charging patterns, manage power flow along distribution lines and incorporate battery storage systems. Using the Tāmaki area as a case study, the models analyse total energy demand and optimal battery storage size, revealing that a 3.49 MWh battery system could mitigate the projected 2040 peak daily grid energy demand of 541.5 MWh and avoid costly power line upgrades. The study also introduces a vehicle-to-grid (V2G) integration model, showcasing its potential to reduce grid dependence and improve energy utilisation. The findings provide critical insights for Auckland’s electricity distribution companies, supporting strategic asset upgrades and offering evidence-based guidance for government policies on EV adoption. In summary, this research provides innovative solutions for optimising EV charging infrastructure, benefiting utility companies and policymakers by informing data-driven decisions. The comprehensive approach, which includes power flow, battery storage, and V2G technology, presents a scalable framework for international cities facing similar challenges, promoting global sustainable transport solutions towards achieving international climate targets and sustainable urban development. Full article

A key challenge facing modern society, fueled by the relentless growth in energy and food requirements, is meeting rising energy needs without exacerbating greenhouse gas emissions. Nevertheless, fossil fuel combustion remains the primary contributor to human-induced pollution. As environmental concerns intensify and fossil resources become increasingly scarce, there is a growing push within the research community to identify alternative energy carriers and to advance more sustainable, low-impact technologies. Thus, this review focuses on catalytic CH₄ decomposition (CDM) for hydrogen production over Ni-, Fe, and Co-metal-based catalysts. Fe-based catalysts have received considerable attention for CDM due to their low cost and environmental sustainability. Furthermore, a discussion of deactivation and regeneration, along with the identified reaction mechanisms of CH₄ decomposition over these catalysts, is presented. Full article

This article presents a novel use case of the deployment of agent-based modeling (ABM) to explore developers’ decision-making along a spectrum of reuse in the built environment. This research project used ABM to model multiple pathways to realizing circularity at the community scale through the reuse of existing buildings and adoption of deconstruction as alternatives to demolition in Ithaca, New York. This exploratory analysis demonstrates (1) the use of ABM in scenario planning, (2) the use of ABM to assess how preservation and building material reuse options affect city-wide greenhouse gas emissions in the form of embodied carbon, (3) and the potential to use the model results in policy analysis. The results of the analysis emphasize trade-offs in local government policies. A Business As Usual scenario produces the most CO₂ emissions and the highest total dollars invested and total square footage developed. This is in contrast to the other three scenarios. A Maximize Preservation scenario achieves the lowest total embodied carbon emissions through retention of existing buildings while maintaining the second highest total investment in urban development. The Deconstruction Incentive and Mandatory Material Reuse scenarios, which involve incentivizing building material reuse, lead to strong ROI signals for developers, reducing the search for suitable properties for new construction as deconstruction becomes a viable avenue for generating returns. ABM-generated scenarios exhibit differences in the performance of developers according to their type and scale. This research produced a readily available ABM and graphical interface that could be used by researchers and local government agencies exploring pathways to achieving circular cities through policies that can affect urban development processes and embodied carbon emissions. Full article

Hydrogen is not intrinsically low-carbon; its environmental value depends on how, where, and with which energy system it is produced. This PRISMA 2020 systematic review synthesizes 28 peer-reviewed life cycle assessment (LCA) studies on major hydrogen production pathways, including steam methane reforming, electrolysis, biomass-based routes, thermochemical cycles, and emerging photoelectrochemical systems. Unlike reviews focused only on carbon intensity, this study jointly evaluates environmental performance, economic feasibility, and technology readiness to identify where apparent advantages remain robust and where they disappear under real deployment conditions. The evidence shows that renewable-powered electrolysis can deliver the lowest greenhouse gas emissions when supported by additional low-carbon electricity, but the same technology can lose its climate benefit in fossil-dominated grids. Biomass and emerging routes diversify supply options but introduce water, land, material, and maturity trade-offs that are often underrepresented in policy narratives. Regional conditions, especially grid carbon intensity and resource availability, explain much of the variation observed across studies. The review also identifies persistent methodological gaps, including inconsistent system boundaries, limited dynamic grid modelling, weak treatment of indirect land use effects, and insufficient accounting for system-level benefits from flexible electrolysis. Overall, the findings support performance-based carbon intensity standards, region-specific deployment strategies, and more transparent LCA methods capable of capturing hydrogen’s role in integrated energy systems. Full article

The transportation sector is a major contributor to global greenhouse gas emissions, driving the need for low-carbon energy solutions. Hydrogen is increasingly recognised as a promising option for decarbonising heavy-duty and long-distance transport; however, hydrogen storage systems contribute significant environmental burdens through material production, manufacturing and end-of-life challenges. This study presents a comparative life cycle assessment of a conventional Type IV composite pressure vessel and a novel additively manufactured, internally reinforced titanium alloy pressure vessel concept for heavy-duty vehicle applications. The two pressure vessel designs were compared within the same available packaging volume on a heavy-duty vehicle. A cradle-to-grave system boundary was applied, covering production, manufacturing, transport, use and end-of-life stages. The environmental assessment was limited to cumulative energy demand and CO₂ emissions, which were used as the metrics for comparing the two hydrogen storage systems. Across the entire life cycle, the Type IV pressure vessel exhibited approximately 16% lower energy demand and CO₂ emissions that the titanium alloy pressure vessel. The use phase dominated both energy demand and environmental impacts, contributing more than 75% of the total life cycle impacts for both pressure vessel designs due to the high energy demand for hydrogen production. For the manufacturing phase, when normalised per kilogram of pressure vessel, the Type IV vessel produced 21.9 kgCO₂eq/kg, compared with 80 kgCO₂eq/kg for the titanium alloy vessel. Material production dominated the cradle-to-gate impact of the titanium alloy pressure vessel, primarily because of the energy-intensive primary production of titanium. Although the use of recycled titanium was also assessed, it reduced the manufacturing stage impacts by only 9%, and the overall impacts remained higher than those of the composite alternative. Full article

Nitrous oxide (N₂O) is a potent greenhouse gas and a major ozone-depleting substance of the nitrogen cycle. While global N₂O budgets focus on microbial soil sources, evidence suggests that living plants can also contribute to N₂O emissions. However, the origin of plant-associated N₂O fluxes is contested: measured emissions may arise from endogenous plant metabolism or merely from transport of soil-derived N₂O. In this review, we clarify these pathways and synthesize current findings from laboratory and field studies. Experimental evidence from ¹⁵N-tracer and axenic-culture studies supports N₂O formation linked to nitrate (NO₃⁻) and nitrite (NO₂⁻) in photosynthetic organisms, although mechanistic resolution varies among taxa. In angiosperms, proposed plastid/chloroplast and hypoxia-associated mitochondrial routes are linked to NO₃⁻/NO₂⁻ metabolism and NO formation, but the terminal NO-to-N₂O step remains unresolved and differs from the flavodiiron-dependent mechanism demonstrated in algae. We discuss key environmental and physiological controls (substrate availability, light, O₂ status, reductant supply) on these processes and highlight methodological challenges in source attribution (chamber artefacts, destructive sampling, isotope analysis). Our analysis suggests that plant-associated N₂O fluxes are real, but highly variable and context-dependent. Rather than assuming generic “plant emission factors”, we emphasize source-specific approaches that distinguish endogenous formation from soil-derived transport and microbial production. This framework can improve N₂O budgets and guide mitigation by indicating whether management should target soil N availability and microbial processes or physiological conditions favouring plant-associated N₂O formation. Full article

Small lakes are widespread, yet their biogeochemistry, particularly regarding greenhouse gases, remains insufficiently studied. This article presents the findings from an investigation of six small lakes in the Southern European part of Russia, conducted from September to October 2024. The primary aim was to examine the coupled distribution of methane (CH₄) and sulfide sulfur (a key metabolite of H₂S) in the lake sediments, in relation to geochemical parameters such as pH, Eh, sediment density, moisture, and the contents of sulfate ions (SO₄²⁻), organic matter, and granulometric composition. The studied sediment layers, reaching depths of up to 110 cm, consist primarily of silty clay. The lakes studied represent both freshwater (0.2–0.7 g/L) and brackish (1.3–24.2 g/L) systems. During the study period, the water column exhibited temperatures of 10.4–22.1 °C, pH values of 7.36–8.53, and dissolved O₂ concentrations ranging from 3.16 mg/L (34% saturation) to 11.79 mg/L (125% saturation). Methane concentrations in the water varied widely, from 1.6 µL/L to 37,380 µL/L. The lowest values were found in the highly mineralized Lake Bolshoy Tambukan (1.6–2.0 µL/L), while exceptionally high concentrations were detected in the bottom waters of the thermally stratified freshwater Lake Staroe. In the shallow, productive freshwater lakes, a significant portion of the organic matter undergoes limited mineralization in the water column and settles to the sediments as partially decomposed remains of sand- and coarse-silt-sized organisms. The subsequent degradation of this labile organic matter reduces bottom-water oxygen, triggering intense anaerobic processes in the upper sediment layer. In these freshwater sediments, where sulfate concentrations are relatively low, sulfate reduction is typically suppressed. Combined with an abundance of labile substrates, this condition fosters intensive methanogenesis, resulting in maximum CH₄ concentrations (33–179 µg/g). Under stable thermal stratification, such high CH₄ concentrations can also accumulate in the bottom water (e.g., up to 37. 4 mL/L in Lake Staroe), posing a risk of significant pulse emissions during autumn mixing. Conversely, the brackish Lake Bolshoy Tambukan exemplifies the crucial role of sulfate reduction, which is stimulated by sulfate-dependent anaerobic oxidation of CH₄. This process acts as a powerful natural biogeochemical barrier that curtails the emission of a major greenhouse gas. The sediments of this lake exhibited minimal CH₄ content (0.14–0.57 µg/g) alongside maximal sulfide sulfur concentrations (1.06–8.57 mg/g). Overall, this theoretical and experimental analysis demonstrates that sulfate reduction is a key determinant of redox potential, acid–base conditions, and the vertical distribution of CH₄ in the anaerobic sediments of small lakes in Southern Russia. Given the projected salinization of lakes in steppe and arid landscapes under climate change, a reduction in CH₄ emissions to the atmosphere is likely due to the enhanced sulfate-dependent anaerobic CH₄ oxidation associated with sulfate reduction in the sediments. Full article

Climate change is one of the most serious global challenges, and greenhouse gas emissions continue to rise despite mitigation efforts. Household consumption accounts for approximately 72% of global emissions, indicating the central role of individual behaviors. Traditional measurement instruments, such as surveys and interviews, are costly, time-consuming, and subject to response biases. User-generated textual content provides an alternative source of evidence, and natural language processing (NLP) enables its analysis at scale. Despite this potential, existing reviews have not systematically mapped its use for individual-level climate behaviors. The main goal of this research is to address this gap through a scoping review following PRISMA-ScR guidelines. Systematic searches were performed in Web of Science, Engineering Village, and Google Scholar, covering January 2015 to April 2026. A total of 2580 records were screened, and ten studies met the inclusion criteria. These studies analyzed Twitter/X, Sina Weibo, Reddit, and e-commerce reviews, covering behaviors from green transportation to waste management. The findings demonstrate that topic modeling and transformer-based models are the dominant techniques, typically combined with sentiment analysis. Recent studies extend beyond describing climate discourse toward explaining behavior. NLP-based text analysis constitutes a scalable complement to surveys and a foundation for targeted climate interventions. Full article

Agricultural management influences progress towards carbon neutrality through its effects on water consumption, energy use, and greenhouse gas (GHG) emissions. However, few studies have translated policies across sectors into management scenarios and evaluated their combined consequences for the agricultural carbon neutrality. We quantified the water, energy use, and carbon nexus for wheat, rice, and corn production across the North China Plain using 2018 as a baseline scenario. We then evaluated conditional management scenarios informed by China’s 14th Five-Year Plan. The three crop production generated net emissions of 1.8 × 10¹⁰ kg C yr⁻¹ in 2018, while cropland net ecosystem productivity offset 16.9% of GHG emissions related to crop production. Energy use was positively correlated with GHG emissions (r = 0.74, p < 0.01). The integrated scenario combining a 30% reduction in nitrogen fertilizer, more efficient nitrogen fertilizer production, sprinkler irrigation, and a 50% crop straw return rate reduced the water footprint, energy use, and GHG emissions by 4.9%, 27.6%, and 39.2%, respectively. By contrast, drip irrigation alone reduced the water footprint but increased energy use by 6.8% and GHG emissions by 12.9%. The results show that water saving measures do not necessarily improve the carbon neutrality when their energy requirements are overlooked. These findings also provide more enlightenment for local policy-makers. Full article

The maritime sector is increasingly focused on green propulsion technologies to address stringent regulations on greenhouse gas emissions and other pollutants. In recent years, research has proposed novel electric and hybrid propulsion architectures and advanced energy management systems. This paper reviews the fundamentals and the most recent developments of hybrid and electric propulsion technologies, evaluating their environmental and economic implications. Particular attention is given to the various onboard energy storage, conversion, and generation technologies, outlining their potential and limitations. Through the analysis of numerous research studies in alternative marine propulsion, the suitability of Li-ion batteries, supercapacitors, flywheels, and different types of fuel cells for maritime transport needs is evaluated, along with the possibilities offered by renewable energy to reduce the environmental impact of marine energy systems. Additionally, it discusses important future directions, research gaps, and emerging paradigms in sustaining maritime eco-systems. Unlike previous reviews that mainly focus on individual technologies, this study provides an integrated analysis connecting propulsion architectures, energy storage systems, fuel cells, alternative fuels, renewable energy integration, and energy management strategies. The review also discusses technology limitations, operational suitability for different vessel categories, and future research challenges toward maritime decarbonization. In presenting these issues, the author’s intention is to promote interdisciplinary cooperation between shipbuilders, policymakers, and researchers for the benefit of more sustainable development of the maritime industry. Full article

Agricultural and livestock production plays an important role in Inner Mongolia, China, but its continued development poses challenges for greenhouse gas mitigation. Using multi-source data from 2005 to 2023, this study integrates the IPCC emission-factor approach, panel STIRPAT modeling, uncertainty and sensitivity analyses, and Ridge regression forecasting to quantify carbon-equivalent emissions and emission intensity from selected agricultural and livestock sources, examine emission changes and associated factors, and project future emissions under a trend-continuation scenario (TCS) and a policy-target scenario (PTS). Total emissions increased from 9.8472 Mt C-eq in 2005 to 14.5223 Mt C-eq in 2023, while carbon-equivalent emission intensity declined over the same period. Livestock-related emissions remained dominant, although the contribution of agricultural emissions increased over time, with cattle and sheep accounting for most livestock-related emissions. Panel estimates showed significant positive associations between emissions and year-end rural population, year-end large-livestock inventory, and real agricultural and animal husbandry output value per capita at constant 2005 prices. Monte Carlo analysis showed that emission-factor uncertainty had a notable influence on absolute emission levels, with a coefficient of variation of 9.04% in 2023; enteric-fermentation CH₄ emission factors for cattle and sheep were the dominant sources of uncertainty. Among the models compared, Ridge regression showed the strongest overall validation performance. Emissions are projected to continue increasing through 2035 under both the TCS and PTS, reaching 16.5974 and 16.5012 Mt C-eq, respectively, indicating that the currently quantifiable policy constraints alone are insufficient to reverse the projected upward trend. Future mitigation should therefore prioritize major livestock-related emission sources and regionally differentiated management, while further refinement of the emission inventory should focus on developing more regionally representative livestock emission factors. Full article