Search Results (976)

Cement production is associated with substantial carbon dioxide (CO₂) emissions due to the high material and energy intensity of Portland clinker manufacture. Partial clinker replacement with supplementary cementitious materials is one of the most promising strategies for reducing the carbon footprint of cement; however, the thermal activation of aluminosilicate raw materials does not always yield highly reactive products. In this study, a pillaring approach is proposed as a controlled method for modifying the structure of clays and unlocking their latent reactivity. Different clay types—namely, kaolinitic, montmorillonitic, and illite–chlorite clays—were sequentially treated with an aluminum sulfate solution and calcined at 650 °C. Their phase composition and microstructure were characterized by X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM), while specific surface area was determined by BET analysis and pozzolanic activity. The results showed that pillaring doubled the specific surface area of montmorillonitic (2:1) and illite–chlorite (2:1:1) clays. Replacing 30% of clinker with pillared clays and limestone increased the compressive strength to 86.5 MPa and the flexural strength to 34.6 MPa. The developed low-carbon composite cements also exhibited high durability: the density of the hardened cement mortar increased to 2.410 g/cm³, the strength loss after 200 freeze–thaw cycles decreased to ≤5.5%, and the sulfate resistance coefficient (Ks) increased to 0.98 (with minimal expansion of the samples <0.02%). The proposed approach makes it possible to reduce the carbon footprint of cement by 25–30% while enabling the use of locally available raw materials for the production of competitive low-carbon green cements. Reported reductions of this order are broadly consistent with the known effect of lowering clinker content through supplementary cementitious materials in blended cement systems. Full article

The building and construction sector is a major contributor to global energy consumption and greenhouse gas emissions, underscoring the need for material-level strategies to minimise environmental impacts throughout the building life cycle. This study presents a life cycle assessment (LCA) of a prototypical two-storey brick veneer residence in Sydney, Australia, using eToolLCD software V4.7 to V5.40. Two environmental impact categories were evaluated, namely embodied energy (EE) and global warming potential (GWP). Over the 55-year reference service life, the case study residence generated a total EE of 1,191,015 MJ NCV and a total GWP of 82,678 kg CO₂ eq, equivalent to 98.18 MJ NCV/m² gross floor area (GFA)/year and 6.816 kg CO₂ eq/m² GFA/year, respectively. The products stage dominated both environmental impact indicators, accounting for 99.35% of total EE and 67.85% of total GWP. Among the building elements, the wall structure was identified as one of the primary contributors, accounting for 29.54% of total EE and 31.12% of total GWP. To identify sustainable alternatives, two international case studies employing AAC block walls were examined, namely, the Wilson Residence in Florida, United States, and the IPCW Residence in Surabaya, Indonesia. A controlled wall area-based comparative environmental analysis of three wall construction systems (brick veneer, AAC blocks, and hollow concrete blocks) demonstrated that the AAC block wall system exhibited the lowest EE (9.752 MJ NCV/m² GFA/year) and GWP (1.2615 kg CO₂ eq/m² GFA/year), representing approximately a 44.1% reduction in EE and 23.9% in GWP compared to the brick veneer wall system. This wall-system finding was corroborated by a supplementary comparative analysis using environmental product declaration (EPD) data for generic AAC blocks and clay brick. Under the specific assumptions, system boundaries, and impact categories examined, AAC block walls demonstrated lower EE and GWP than brick veneer walls in this Sydney case study residence, indicating their potential as a lower-impact wall material for Australian residential construction. Compared to brick veneer walls, AAC block walls may reduce both EE and GWP while maintaining high thermal performance, durability, and construction efficiency, thereby contributing to more sustainable housing and support Australia’s transition towards net-zero emissions. Full article

Calcined clays are increasingly recognized as strategic supplementary cementitious materials for reducing clinker consumption and the environmental impacts of construction. However, life cycle assessments typically represent metakaolin production using a single carbon footprint value, despite substantial differences in calcination technology, energy supply, and feedstock characteristics. This study develops a parameterized cradle-to-gate carbon inventory for metakaolin production and evaluates how this variability affects the environmental assessment of low-carbon construction materials. The methodology combines process-based theoretical modeling, mass and energy balances, literature-derived industrial data, and life cycle assessment. A full-factorial scenario analysis was performed for three calcination technologies: rotary kiln, fluidized bed, and flash calcination, while systematically varying fuel source, electricity mix, kaolinite purity, feedstock moisture, and transport distance. The resulting inventories were subsequently propagated into representative LC3 cement and metakaolin-based geopolymer formulations to quantify their influence at the construction-material level. Across 648 production scenarios, the carbon footprint of metakaolin ranged from 34 to 578 kg CO₂e t⁻¹, demonstrating that production conditions define the environmental performance. Fuel selection was identified as the principal emission driver, while moisture content and feedstock purity produced secondary effects. The variability propagated to downstream products, resulting in carbon footprints of 363–527 kg CO₂e t⁻¹ for LC3 cement and 167–357 kg CO₂e m⁻³ for metakaolin-based geopolymers despite identical material compositions. For the building sector, the proposed framework enables designers, material producers, and LCA practitioners to select calcined clay production routes consistent with the carbon targets of concrete, mortar, masonry, precast elements, and other cement-based building applications. It therefore provides a practical basis for incorporating LC3 and geopolymer technologies into lower-carbon building projects while avoiding environmental benefits based on non-representative upstream assumptions. Full article

Circular economy is today a key driver of every transformation process aimed at reducing and optimizing the use of energy and materials. The production of solid biofuel from waste is a typical route to lower the potential impact of greenhouse-gas emissions. In this context, olive pomace is a relevant feedstock, as 4 million tonnes are generated worldwide each year alongside olive oil production. However, only a small fraction of olive pomace is currently valorized. Fresh olive pomace must first be quickly dried to a low, controlled moisture. This step is performed poorly and at a high energy cost. This paper presents an automation-based approach to enhance biomass production from olive pomace, thereby advancing circular-economy practices in olive oil production. The work is focused on four aspects. In the first part, a review of the state of automation in agricultural engineering with a focus on biomass and olive pomace is proposed. Then, the design and construction of an innovative drying system that integrates an infrared solution directly into the transporting screw conveyor is described, integrating real-time online microwave moisture sensing and PLC control. After that, a cloud-based service is presented for remote monitoring, data analysis, and optimization. The innovative and automated drying system was validated during a preliminary field campaign at an olive mill. After about sixteen hours of continuous, cloud-monitored operation, the resulting olive pomace moisture fell below the 5% threshold across a wide range of inlet-moisture conditions, with a stable electrical power demand of approximately 1.85 kW. Finally, an environmental analysis is provided to evaluate the environmental aspects related to the proposed system. The preliminary analysis confirms a significant avoided-carbon potential if the resulting olive pomace is reused as biomass for energy production. The impact associated with 1 kWh_-eq produced from olive pomace is in the range of 0.006–0.033 kg CO_2-eq. Full article

This study presents a system-level and subsystem-level evaluation of energy performance in an industrial polyethylene film production system based on real operational data. The analysis focuses on specific energy consumption (SEC) as a key performance indicator, considering both total system behavior and the contribution of energy-intensive subsystems, namely extrusion and converting processes. The initial system exhibits SEC values ranging from 1.267 to 1.688 kWh/kg, indicating relatively high energy intensity compared to established industrial benchmarks. Following technological modernization, SEC is reduced to 0.43 kWh/kg for extrusion and 0.09 kWh/kg for converting, corresponding to improvements exceeding 60%. The total annual energy saving potential is estimated at 906 MWh (39%), accompanied by a proportional reduction in CO₂ emissions. The results demonstrate that energy performance is strongly influenced by production load, material losses, and process stability. The novelty of the study lies in the subsystem-level quantification of energy performance using real industrial data and in the identification of the interaction between production efficiency, waste generation, and energy consumption. The findings provide a practical framework for energy optimization in polymer processing systems and allow comparison with European best practices. Full article

Biocomposites reinforced with natural fibres are receiving increased attention due to growing concern over the environmental impacts of their synthetic counterparts. Grass mowed from roadside verges has the potential to serve as an alternative to commonly used natural fibres and as a renewable feedstock for the biocomposite industry. However, it is generally treated as waste due to its high volume, seasonal availability, contamination (e.g., with metals and plastic bottles), and legal status. In this study, a techno-economic assessment was performed for different roadside grass valorisation scenarios covering the entire value chain from mowing and pre-treatment to fibre and biocomposite granule production. In addition, a screening greenhouse gas emissions assessment based on the main energy and material inputs was performed for fibre production. This screening assessment provides an initial indication of the operational environmental performance and is not intended to represent a complete life cycle or integrated sustainability assessment. One scenario investigated a value chain with flail mowing and grass fibres as the final product. Grass fibres can be produced at €528/t when mowing costs are included and as low as €295/t when mowing costs are excluded under the processor/incremental-cost perspective. A reduction of 6.4% in fibre price was estimated for the rotary-mowing scenario when mowing costs were excluded. In comparison, the market price of commonly available natural fibres ranges from €300 to €4000/t, although the price is strongly dependent on fibre quality, which was not considered in this assessment. Another scenario considered biocomposite granules consisting of 25% fibres, 60% polylactic acid, and 15% filler as the final product. The biocomposite granules can be produced at €1073/t and €1013/t with and without mowing costs, respectively. The production cost of the granules is largely influenced by the price of the polymer matrix and the compound composition, while the average market price is approximately €2000/t. Overall, the results indicate that roadside grass fibres may be cost-competitive under the evaluated assumptions. The screening assessment resulted in 364.20–701.32 kg CO₂-eq/t fibre for the flail system and 275.96–327.96 kg CO₂-eq/t fibre for the rotary system, depending on whether mowing was excluded or included. Drying energy and diesel consumption associated with mowing and collection were identified as the main operational emission sources. Full article

The building and public works sector is a major source of greenhouse gas emissions in developing countries due to the high material intensity of infrastructure and the dependence on imported materials. In Burkina Faso, as in most African countries, environmental assessments remain limited by the lack of locally representative emission factors, creating uncertainty in carbon accounting. This study estimates emission factors for key construction materials in Burkina Faso using a simplified cradle-to-gate Life Cycle Assessment (LCA) adapted to national technical, energy, and logistical conditions. The materials analyzed include cement, steel, flat glass, aluminium, aggregates, sand, timber, ceramic tiles, paint, bitumen, and asphalt mixes. The results reveal significant variations in the carbon intensity of construction materials in the Burkina Faso context. Aluminium exhibits the highest emission factor (12.804 tCO₂/t), followed by paint (2.50 tCO₂/t), steel (1.970 tCO₂/t), Portland cement (1.060 tCO₂/t), ceramic tiles (0.99 tCO₂/t), flat glass (0.84 tCO₂/t), bitumen (0.628 tCO₂/t), asphalt mixes (0.130 tCO₂/t), timber (0.16 tCO₂/t), aggregates (0.008 tCO₂/t), and sand (0.0013 tCO₂/t). Portland cement exhibits a slightly higher emission factor than the values commonly reported in the literature (0.85–0.95 tCO₂/t), while steel, aluminium, flat glass, ceramic tiles, bitumen, asphalt mixes, timber, and paint remain within internationally reported ranges. In contrast, sand exhibits a slightly lower emission factor than typical literature values, reflecting its limited processing requirements. Aggregates and sand show the lowest emission factors due to minimal industrial processing and greater local availability. These differences are mainly driven by import dependence, long- distance maritime and road transportation, the characteristics of the national electricity mix, and local production conditions. The study supports the development of context-specific carbon assessments and environmental databases for Burkina Faso and other West African countries. Full article

The development of low-cost and sustainable adsorbents for carbon dioxide (CO₂) capture has gained increasing attention as a strategy to mitigate greenhouse gas emissions. In this study, activated biochars produced from babassu, elephant grass, and Pinus elliottii were evaluated as CO₂ adsorbents after different activation treatments. The biochars were produced by slow pyrolysis at 400 °C and subsequently modified using three activation routes: steam activation, chemical activation with KOH, and KOH activation followed by acid washing. The materials were characterized by proximate analysis, specific surface area measurements, scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy, and CO₂ adsorption tests. Steam activation produced the highest specific surface areas, reaching 1270.53, 1027.28, and 907.87 m² g⁻¹ for babassu, elephant grass and Pinus, respectively. Despite the superior textural properties achieved through steam activation, the highest CO₂ adsorption capacities were obtained for the samples subjected to chemical activation followed by acid washing. These results indicate that adsorption performance is governed not only by the development of surface area but also by pore accessibility and the surface chemistry of the adsorbent. Maximum adsorption capacities of 82.78, 81.19, and 85.24 mg g⁻¹ were obtained for ACKAW B, ACKAW CE, and ACKAW P, respectively. Adsorption–desorption cycling experiments demonstrated regenerability and stable performance over repeated cycles. The results indicate that KOH activation followed by acid washing is an effective strategy for producing high-performance biochar-based adsorbents for CO₂ capture. Full article

Road tunnels are highly carbon-intensive due to material use, energy-intensive construction, and long service lives, yet major gaps remain regarding emission hotspots, construction method comparisons, and regional differences, particularly in Central and Eastern Europe. This article combines a PRISMA 2020-guided systematic literature synthesis with a Polish case-study life-cycle assessment (ISO 14040/14044, cradle to grave, functional unit of 1 m of tunnel, 100-year horizon) using Ecoinvent factors and the Polish energy mix, covering material production, construction, operation, maintenance, and end of life. The literature synthesis found substantial variability in tunnel carbon emissions, ranging from 1500 to 22,062 t CO₂-eq per lane-kilometer depending on the construction method, tunnel type, and region. Material production was the largest contributor to construction-phase emissions (70–95%), with concrete and steel responsible for over 90% of material-phase impacts and 75–80% of construction-phase emissions, while operational energy use dominates over the full life cycle. Concrete and steel substitution (e.g., GFRP bars and calcium sulfoaluminate cement) offers the greatest construction-phase reduction potential, while operational measures, such as LED lighting, demand-controlled ventilation, and renewable energy, can cut long-term energy use by 30–50%. For Poland, low-carbon concrete, prefabrication, and renewable electricity could reduce tunnel emissions by 40–60%. These findings highlight pathways for decarbonizing tunnel infrastructure through material innovation, energy-efficient operation, and circular economy principles. Full article

High-solar-reflectivity cladding materials are widely promoted to reduce cooling demand and mitigate urban heat island effects. However, in cold and mixed climates, their overall energy and carbon performance remains uncertain due to potential winter heating penalties and embodied carbon trade-offs. This study presents a comparative evaluation of energy use, annual operational carbon emissions, and material-level embodied carbon for high-reflectivity cladding applied to commercial buildings across representative Canadian climate zones. Dynamic simulations were conducted in EnergyPlus using a standardized warehouse archetype in Montreal, Toronto, and Vancouver, representing cold continental, mixed continental, and marine climates. Roof and wall solar reflectivity (albedo) was varied from 0.2 (baseline) to 0.8 (high reflectivity), while other envelope properties remained constant. Increasing reflectivity reduced annual cooling demand by approximately 15% in Montreal and Toronto and 20% in Vancouver, with the largest reductions during peak summer periods. However, reduced winter solar heat gains produced heating penalties, increasing total annual energy use by 1% in Montreal, 0.5% in Toronto, and less than 0.5% in Vancouver. Operational greenhouse gas emissions were calculated by converting simulated annual electricity and natural gas use into CO₂-equivalent emissions using provincial grid emission factors and combustion factors consistent with Environment and Climate Change Canada reporting. The results demonstrate the strong influence of regional energy supply on operational carbon outcomes. A cradle-to-gate (A1–A3) life cycle assessment quantified embodied carbon of representative cladding materials using Environmental Product Declarations and North American databases. Embodied carbon varied considerably: product-specific steel cladding manufactured in low-carbon electricity regions showed global warming potential as low as 1.76 kg CO₂e/kg, compared with industry averages exceeding 2.4 kg CO₂e/kg. Rather than performing a complete whole-life carbon assessment, this study comparatively evaluates annual operational carbon emissions and material-level embodied carbon to improve understanding of the energy and carbon implications of high-solar-reflectivity cladding materials in representative Canadian climates. The results demonstrate that climate conditions, envelope thermal performance, regional energy supply, and manufacturing pathways influence the environmental performance of cool envelope strategies. Full article

The construction industry accounts for a substantial share of global greenhouse gas emissions, underscoring the need to explore sustainable building technologies. Bamboo is a rapidly growing renewable resource used in various building contexts, including structural and non-structural purposes, with properties equivalent to those of other conventional building materials. The objective of this research was to compare the environmental life cycle assessment impact of bio-based bamboo floor construction with that of conventional concrete floors using a cradle-to-grave and EoL of 60 years for both materials. Comparing the data extracted from the analysis of a square metre of floor system using bio-based construction materials, the LCIA, using the database Simapro 9.5, revealed that bio-based alternatives generally have lower environmental impacts compared to conventional materials. The study establishes that whereas the global warming potential carbon (GWPC) per square metre of concrete floor recorded a mid-point result of 160 kg CO₂-eq, that for bamboo was 12 kg CO₂-eq, with bamboo exhibiting additional carbon sequestration during the growth period. The mid-point result for the acidification potential was 0.68 kg SO₂-eq and 0.12 kg SO₂-eq for concrete and bamboo, respectively, with bamboo showing an 82% improvement over concrete. Again, the eutrophication potential revealed that bamboo showed a 78% improvement over concrete. When analysed within the context of rapidly urbanising regions like Ghana, these LCIA findings provide a strong empirical justification for substituting traditional grey building materials with bio-based structural composites. Concrete and steel remain highly exposed to supply chain energy premiums, given the high energy demands during the clinker and steel production phases. Transitioning urban building models to structurally engineered bamboo could successfully mitigate localised urban heat retention and lower municipal scope 3 emissions. Full article

Hospital buildings (HBs) are among the most energy-intensive public buildings, yet their life-cycle carbon characteristics, emission drivers, and long-term mitigation potential remain insufficiently quantified. This study establishes a comprehensive life-cycle carbon assessment framework for HBs based on life cycle assessment (LCA), using a Grade-A tertiary hospital in Shenzhen, China, as a case study. The framework quantifies carbon emissions across the materialization, operation, and demolition stages, and estimates operational emissions from public hospital buildings at the city scale. Logarithmic Mean Divisia Index (LMDI) decomposition and Long-range Energy Alternatives Planning (LEAP) modeling were subsequently applied to identify historical drivers and evaluate future mitigation pathways. The results show that the case hospital generated approximately 0.57 Mt CO₂e of gross life-cycle carbon emissions over a 50-year service life, with the operational stage dominating approximately 88% of net emissions. Electricity consumption accounted for 94% of operational energy-related emissions, while HVAC systems and the Diagnostic departments were identified as major carbon hotspots. At the city scale, the gross operational emissions of 73 public hospitals in Shenzhen were estimated at approximately 0.74 Mt CO₂e in 2020 within the defined accounting boundary. For the broader citywide hospital sector, LMDI analysis revealed that annual operational emissions increased from approximately 0.25 Mt CO₂e in 2006 to 0.91 Mt CO₂e in 2020, primarily driven by healthcare service demand and hospital infrastructure expansion, whereas the declining operational carbon emission coefficient provided a partial offset. LEAP scenario analysis further demonstrated that net operational emissions peaked in 2050 under BS and in 2030 under SI and SII. Under SIII, emissions declined continuously from the 2020 base-year level to approximately 0.29 Mt CO₂e in 2060, representing a reduction of approximately 68%. These findings highlight the necessity of coordinate building energy optimization, healthcare infrastructure development, and energy system decarbonization for low-carbon transformation of hospital buildings. 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

Understanding the carbon emission characteristics of fused filament fabrication (FFF) is important for the development of more sustainable additive manufacturing practices. This study presents a framework for quantifying, modelling, and optimizing the carbon emissions of FFF-printed specimens of carbon-reinforced Polyethylene Terephthalate Glycol (PETG-CF) composite. Carbon emissions were assessed within a cradle-to-gate system boundary by considering material consumption and electrical energy usage during fabrication. The influence of print speed, raster angle, layer height, infill density and infill pattern on carbon emissions were experimentally investigated. Response Surface Methodology (RSM) was utilized to formulate a predictive carbon emission model, while analysis of variance was applied to assess the significance of the process parameters. The findings revealed that infill density, infill pattern, layer height, and raster angle significantly affected carbon emissions, while print speed showed a comparatively lower influence. Contour plot analysis was used to visualize parameter interactions and identify low-emission regions. RSM-based optimization predicted a minimum carbon emission of 0.0732 kgCO₂eq at a print speed of 220 mm/s, layer height of 0.12 mm, infill density of 50%, raster angle of 0°, and rectilinear infill pattern. The proposed framework presents a practical strategy for integrating carbon emissions for a sustainable FFF process. Full article

Natural blue calcite is relatively rare, and its coloration and luminescence mechanisms have not been systematically established. In this study, four natural blue calcite samples from China were comprehensively characterized using mineralogical testing, X-ray diffraction (XRD), electron probe microanalysis (EPMA), scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDS), Fourier-transform infrared spectroscopy (FTIR), Raman spectroscopy, ultraviolet–visible spectroscopy (UV-Vis), photoluminescence (PL), and electron paramagnetic resonance (EPR). XRD confirms single-phase trigonal calcite (space group R-3c). EPMA detects minor Mg, Fe, Cu, and Sr, with smaller-radius Mg²⁺, Fe²⁺, and Cu²⁺ being the main contributors to the contraction through isomorphous substitution for Ca²⁺. UV-Vis spectra show characteristic absorptions at 270 nm and 340 nm related to lattice defects with a broad emission band centered at 480 nm in the PL spectra. EPR detects a CO₂⁻ radical center (g = 2.003), and the same signal is also observed in the colorless sample. The colorless sample also contains the same CO₂⁻ radicals, indicating that these radicals alone do not account for the blue coloration. A broad 480 nm blue-violet fluorescence band is observed in the four blue samples under 405 nm excitation. These findings provide a spectroscopic and crystallographic basis for distinguishing natural blue calcite from analogous materials and for understanding the origin of its color and luminescence. Full article