Global CO2 Research Articles

Corelease of Genotoxic Polycyclic Aromatic Hydrocarbons and Nanoparticles from a Commercial Aircraft Jet Engine - Dependence on Fuel and Thrust.

Jet engines are important contributors to global CO2 emissions and release enormous numbers of ultrafine particles into different layers of the atmosphere. As a result, aviation emissions are affecting atmospheric chemistry and promote contrail and cloud formation with impacts on earth's radiative balance and climate. Furthermore, the corelease of nanoparticles together with carcinogenic polycyclic aromatic hydrocarbons (PAHs) affects air quality at airports. We studied exhausts of a widely used turbofan engine (CFM56-7B26) operated at five static thrust levels (idle, 7, 30, 65, and 85%) with conventional Jet A-1 fuel and a biofuel blend composed of hydro-processed esters and fatty acids (HEFA). The particles released, the chemical composition of condensable material, and the genotoxic potential of these exhausts were studied. At ground operation, particle number emissions of 3.5 and 0.5 × 1014 particles/kg fuel were observed with highest genotoxic potentials of 41300 and 8800 ng toxicity equivalents (TEQ)/kg fuel at idle and 7% thrust, respectively. Blending jet fuel with HEFA lowered PAH and particle emissions by 7-34% and 65-67% at idle and 7% thrust, respectively, indicating that the use of paraffin-rich biofuels is an effective measure to reduce the exposure of airport personnel to nanoparticles coated with genotoxic PAHs (Trojan horse effect).

Assessment of CO2 Capture in FA/GGBS-Blended Cement Systems: From Cement Paste to Commercial Products

The cement industry’s intricate production process, including kiln heating and fossil fuel use, contributes 5–8% of global CO2 emissions, marking it as a significant carbon emitter in construction. This study focuses on quantifying CO2 capture potential in blended cement systems through the utilisation of phenolphthalein and thermalgravimetric methodologies. Its primary objective is to assess the CO2 absorption capacity of these blended systems’ pastes. Initial evaluation involves calculating the carbon capture capacity within the paste, subsequently extended to estimate CO2 content in the resultant concrete products. The findings indicate that incorporating ground granulated blast-furnace slag (GGBS) or an ettringite-based expansive agent did not notably elevate carbonation depth, irrespective of their fineness. Conversely, the introduction of fly ash (FA) notably augmented the carbonation depth, leading to a substantial 36.4% rise in captured CO2 content. The observed distinctions in carbonation behaviour primarily stem from variances in pore structure, attributable to distinct hydration characteristics between GGBS and FA. Thermal analysis confirms the increased stabilisation of CO2 in FA blends, highlighting the crucial influence of material composition on carbonation and emission reduction. Incorporating both GGBS and FA notably diminishes binder emissions, constituting almost half of PC-concrete emissions. Initially, 60% GGBS shows lower emissions than 50% FA, but when considering CO2 capture, this emission dynamic significantly changes, emphasising the intricate influence of additives on emission patterns. This underscores the complexity of evaluating carbonation-induced emissions in cementitious systems.

Carbonate factory response through the MECO (Middle Eocene Climate Optimum) event: Insight from the Apulia Carbonate Platform, Gargano Promontory, Italy

During the Eocene, shallow-water carbonate systems were significantly impacted by climate fluctuations and hyperthermal events. Following the peak temperatures of the Early Eocene Climatic Optimum (EECO), a general cooling trend began, with short-lived (⁓200 kyr) warming events occurring alongside it. In the early Bartonian (around 40.1 Ma), a warming event known as the Middle Eocene Climatic Optimum (MECO) occurred, lasting approximately 500,000 years. In this scenario, the types and calcification rates of marine organisms such as corals and larger benthic foraminifera (LBF) were influenced by global CO2 and oceanographic changes, which had a major effect on photic carbonate factories. To better understand the effects of these factors on carbonate factories, a detailed study of shallow-water facies types, distributions, and evolution was conducted. The Middle Eocene Monte Saraceno sequence, located on the eastern margin of the Apulia Carbonate Platform (Gargano Promontory, southern Italy), was selected as a case study to investigate the relationships between carbonate factory types and climatic changes around the MECO event. This study identified two distinct intervals with different modes of carbonate production, separated by a sharp boundary. The lower interval consists of clinostratified, thick beds of rudstone to floatstone, mostly made up of various large Nummulites tests, indicating an early Bartonian age (Shallow Benthic Zone 17). Instead, the upper interval consists of coral floatstone to rudstone with a packstone matrix, rich in branching corals in association with gastropods, bivalves, and rare small larger benthic foraminifera. The appearance of Heterostegina sp. and Glomalveolina ungaroi in this interval indicates a late Bartonian age (Shallow Benthic Zone 18). By integrating biostratigraphic and stable-isotope data, the lower interval, with abundant Nummulites, was linked to the MECO event, during which higher sea-surface temperatures seem to enhance larger benthic foraminifera proliferation, as already occurred in the Early Eocene. However, in the late Bartonian, the sharp transition to a coral-dominated carbonate factory, with rare larger benthic foraminifera showing smaller sizes, could be attributed to a drop in temperature that created the conditions more favourable to corals. Overall, this study provides compelling evidence of how environmental changes can affect marine carbonate production, also highlighting the importance of investigating these relationships, to better understand climate change in the past, present and near future.

Weakened relationship between tree growth and nitrogen availability due to global CO2 increase and warming in the Taibai Mountain timberline, central China

Abstract Climate warming, rising atmospheric CO2 concentration (Ca), and nitrogen (N) availability are exerting profound impacts on global forest ecosystems, particularly in high-altitude mountains. This study investigated the tree-growth dynamics of timberline Larix chinensis in the Taibai Mountain, central China, and explored its ecophysiological responses to environmental stresses by combining tree growth and stable isotopes. The results showed that the growth rate of L. chinensis has significantly increased since the 1960s, and that tree growth in this timberline was particularly sensitive to temperature in spring. Moreover, the continuously rising intrinsic water-use efficiency (iWUE), linked to higher Ca and warmer environment, promoted the growth of L. chinensis. Before the 1960s, tree-ring δ15N gradually increased, then shifted to an insignificant decline with the acceleration of tree growth, and broke the preexisting carbon–nitrogen balance. Meanwhile, climate warming and increased iWUE have replaced N as the principal drivers of tree growth since the 1960s. It is believed that L. chinensis may gradually suffer a decline in N availability as it continues to grow rapidly. The insightful understanding of the biochemical mechanisms of plant responses to growth-related environmental conditions will improve our ability to predict the evolution of high-elevation mountain ecosystems in the future.

Comparing Methodologies for Stomatal Analyses in the Context of Elevated Modern CO2.

Leaf stomata facilitate the exchange of water and CO2 during photosynthetic gas exchange. The shape, size, and density of leaf pores have not been constant over geologic time, and each morphological trait has potentially been impacted by changing environmental and climatic conditions, especially by changes in the concentration of atmospheric carbon dioxide. As such, stomatal parameters have been used in simple regressions to reconstruct ancient carbon dioxide, as well as incorporated into more complex gas-exchange models that also leverage plant carbon isotope ecology. Most of these proxy relationships are measured on chemically cleared leaves, although newer techniques such as creating stomatal impressions are being increasingly employed. Additionally, many of the proxy relationships use angiosperms with broad leaves, which have been increasingly abundant in the last 130 million years but are absent from the fossil record before this. We focus on the methodology to define stomatal parameters for paleo-CO2 studies using two separate methodologies (one corrosive, one non-destructive) to prepare leaves on both scale- and broad-leaves collected from herbaria with known global atmospheric CO2 levels. We find that the corrosive and non-corrosive methodologies give similar values for stomatal density, but that measurements of stomatal sizes, particularly guard cell width (GCW), for the two methodologies are not comparable. Using those measurements to reconstruct CO2 via the gas exchange model, we found that reconstructed CO2 based on stomatal impressions (due to inaccurate measurements in GCW) far exceeded measured CO2 for modern plants. This bias was observed in both coniferous (scale-shaped) and angiosperm (broad) leaves. Thus, we advise that applications of gas exchange models use cleared leaves rather than impressions.

Effects of Organic Additives on Portlandite Microstructure during CaO Hydration

This study evaluates the effect of various organic additives on the microstructure of portlandite crystals during the hydration of CaO. Calcium hydroxide mixed with selected additives was prepared and characterised in terms of crystal size and habit, platelets abundance, and particle size distribution using various techniques such as XRD, SEM and Particle Size Analysis. The results suggest that the microstructure of portlandite is altered by the presence of carbohydrates and sulfonates, showing higher platelets abundance, smaller crystallite size, and higher specific surface area. The presence of hydroxyl-rich carbohydrates induces more marked effects compared to sulfonates. These results show that it is possible to tailor the properties of lime to specific applications in both, the conservation and the construction industry. Furthermore, the results show that it is possible to enable the development of materials specifically dedicated to other applications such as the synthesis of precipitated calcium carbonate and the design of CO2 sorbents, all of which will have the added value of reducing the global anthropogenic CO2 emissions.

How Age and Gender Affect the Carbon Footprint of the Population in Croatia

The term carbon footprint refers to the amount of carbon dioxide equivalent (CO2) released into the atmosphere through daily activities. The goal of the European Union is to become climate neutral by the 2050, i.e., to achieve carbon neutrality, which means achieving a balance between carbon emissions and its absorption from the atmosphere into carbon sinks. With the guidance of the Green Plan, by 2050, Europe is to become the first continent to eliminate as much CO2 emissions as it produces. Global annual CO2 growth is 1.4%. According to data from 2016, global scale of emissions was around 50 billion t/y. of CO2 (an increase of 40% compared to 1990). Croatia emitted 17.88 million tons of CO2 and EU emitted total of 2.92 billion tons. While carbon footprint can be reduced by improving energy efficiency and changing lifestyles and habits much of it depends on personal characteristics of individuals and societal values, age, gender, place of residence and habits are elaborated in this paper. Statistical methods were used to process and analyze the results.

Using Multisource Data and Time Series Features to Construct a Global Terrestrial CO₂ Coverage by Deep Learning

Using Multisource Data and Time Series Features to Construct a Global Terrestrial CO₂ Coverage by Deep Learning

The pathway to net-zero emission in aviation – How much can we rely on sustainable aviation fuel?

The aviation industry is under constant pressure to reduce its environmental footprint and eventually achieve net-zero carbon emissions by 2050. In order to accomplish this ambitious but necessary goal, a variety of measures have been employed over the last two decades, among which the application of sustainable aviation fuels (SAFs) plays a prominent role. Policymakers aim at substituting 80-90% of aviation fuel by SAF in 2050, thus reducing global aviation CO2 emissions by 62%. In theory, these fuels can already be integrated in up to 50% of the fuel capacity of current aircraft as “drop-in” fuels. However, due to numerous operational and regulatory barriers surrounding the exploitation of SAF, it is still not clear how, in combination with traditional jet fuel, it will affect the cost aspect of airline operations. Considering the traffic projection provided by EUROCONTROL according to which the traffic will undoubtedly increase in the next decade, the aim of the paper is to provide a preliminary assessment of the financial impact of SAF on an airline's total fuel cost. For this purpose, the analysis is based on a single carrier that follows a hybrid business model and mainly focuses its operation on intra-European routes. Creating different scenarios for SAF's future costs as well as the share of SAF in total fuel required, this paper provides some realistic results that may serve as a solid foundation for the airline to better understand the implications of SAF on its financial aspects, keeping in mind that fuel costs still constitute a large portion in an airline's direct operating costs. The proposed methodology may be applied to any carrier with an interest in SAF.

Cross-Correlation between Global Temperature and Atmospheric CO<sub>2</sub> with a Temperature-Leading Time Lag

Cross-Correlation between Global Temperature and Atmospheric CO<sub>2</sub> with a Temperature-Leading Time Lag

Topology Optimization in 3D Concrete Printing to Reduce Greenhouse Gas Emissions

The construction industry, responsible for 9% of global CO2 emissions and 40% of extracted natural resources, faces the challenge of reducing Greenhouse Gas (CH4, N2O, fuorinated gases, and CO2 dominant in the civil sector) emissions and managing waste sustain-ably. To address these challenges, a digital design for manufacturing methodology is proposed, which combines gradient-based topology optimization (TO) with additive manufacturing (AM) for cementitious structural design, leveraging the advantages of complex and non-traditional optimized forms. The methodology entails initially creating a finite element (FE) simulation for TO to minimize compliance within the three-dimensional design domain, taking into account volume workspace and other AM constraints. Following this, the optimized design is converted into a CAD model, and a CAM script is generated in G-Code language. Subsequently, the design is executed through a 3D Concrete Printing (3DCP) system, thereby integrating CAD-CAE-CAM technologies. The research evaluates the potential for mass reduction through TO structures and carbon dioxide emissions of 3DCP compared to traditional methods, emphasizing the potential of digital fabrication for eco-efficient construction. The observed margin highlights promising opportunities for the optimization and implementation of sustainable practices in the field of civil engineering and construction.

Dry reforming of steelworks off-gases in a pilot plant integrated into a steel mill: influence of operating parameters

Next step forward towards green steel! A pilot plant integrated into a steel mill has been operated successfully and shows promising results. This novel, retrofitted process for steel production has the potential to cut global CO2 emissions by 0.5%!

Dosagem de argamassas de alta resistência ecoeficientes otimizadas pelo modelo de empacotamento compressível

Abstract The production of eco-efficient cement-based materials is essential to reduce CO2 emissions from the construction industry. A substantial reduction in global CO2 emissions can be achieved by using clinker in mortar and concrete more efficiently and using low-CO2 minerals as partial replacements for Portland cement. However, the proportioning of eco-efficient composites is complex and the reduction in clinker content may affect its properties. This paper aims to optimize the mix design of high-strength mortars containing supplementary cementitious materials (limestone filler, fly ash, metakaolin, silica fume). The compressible packing model associated with a simplex mixture design were used together with chemical parameters, to limit the amount of active SCMs for the model iterations. The results show a significant decrease in the environmental impact of the mortars, which presented compressive strengths between 76 and 118 MPa at 91 days and binder indexes between 10 and 15 kg/m3/MPa. The reactivity of the SCMs (based on the modified Chapelle test) were successfully used to establish the Portland cement substitution (up to 13%), preventing the presence of unreacted SCMs and optimizing the use of limestone filler and sand, which have a lower environmental impact. The high-performance blends reached 8.73 kg CO2e/MPa, up to a 30% reduction in CO2e emissions compared to the mortar with only Portland cement.

Sustainable Infrastructure Development in Indonesia: A Quantitative Evaluation of CO2 Emission Reduction from Fly Ash-Cement Substitution in Ready-Mix Concrete

The construction industry is a major contributor to global CO2 emissions, particularly through Portland cement production. In Indonesia, the utilization of fly ash in ready-mix concrete presents a promising approach to sustainable construction. This strategy aligns infrastructure development with environmental objectives by potentially reducing emissions and supporting global climate change mitigation efforts. This study investigates the environmental impact of incorporating fly ash into ready-mix concrete employed for the Yogyakarta-Bawen toll road project, with a specific focus on CO2 emission reduction. Recognizing the critical role of sustainable construction practices in addressing climate change, this research aims to quantify the environmental benefits of substituting 40% of Portland cement with fly ash in FC 30 MPa ready-mix concrete. A comprehensive analysis revealed an 18% decrease in emissions associated with coarse aggregate and a 55% decrease from cement, despite a marginal increase from fine aggregate. Overall, this method achieved a significant 47% reduction in total CO2 emissions, demonstrating the effectiveness of fly ash in enhancing the sustainability of construction materials. This substantial reduction underscores the potential of fly ash integration as a key strategy for mitigating the environmental impact of large-scale infrastructure projects.

The impact of lime as a replacement of cement-based mortar, on the water absorption and rain penetration of masonry

Since the 1970s, the rise of cement-based mortars has overtaken the traditional lime mortar in construction. This marks a drastic change from circular traditions of reusing ceramic facade materials to a linear economy with an increased difficulty in the reuse of bricks. Lime mortar joints make the recovery of bricks manageable, while cracks can easily occur during dismantling of cement-based masonry. This has prompted a resurgence in the use of lime mortar especially in historical restoration and renovation. It also presents lower CO2 emissions compared to cement mortar, which is a crucial aspect in an industry responsible for 37% of global CO2 emissions. Lime has the ability to capture up to 90% of its production CO2 through carbonation further emphasizes its environmental advantages. This study investigates the hygrothermal behaviour of a hybrid construction with load-bearing masonry, and an interior lime-hemp insulation. Typically, lime mortar exhibits higher moisture transport and storage characteristics, enhancing masonry waterproofing compared to cement mortar. Eighteen setups are subjected to rain-tightness tests in order to monitor potential water infiltration. During these tests, visual evaluations, weight, and moisture measurements are conducted to monitor moisture absorption and rain infiltration to assess the performance of lime mortar versus cement-mortar. This research contributes to sustainable building practices by promoting the advantages of lime mortar in enhancing material reuse, reducing CO2 emissions, and improving the hygrothermal performance.

Environmental consequences of Japan's ban on sale of new fossil fuel-powered passenger vehicles from 2035

Despite the recent increase in vehicle electrification, the transport sector remains a major contributor to the rise in global CO2 emissions. Using dynamic product lifecycle (LC) models, we analyzed the relationship between LC-CO2 emissions and the proportion of electric vehicle (EV) sales in Japan, where the introduction of EVs could increase LC-CO2 emissions. We considered the contributions of vehicle fuel efficiency and vehicle lifetime to LC-CO2 emissions under three scenarios—changes in sales, improvements in fuel efficiency, and changes in vehicle lifetimes. Our findings show that promoting EVs and decarbonization in the electricity sector will decrease CO2 emissions during the driving phase. However, even if the energy mix follows the net zero emission target, emissions from the vehicle manufacturing phase will largely remain, and the manufacturing emissions from electric will account for over 50% of the total emissions in 2050, even when the vehicle lifetime is extended by 5 years. Although the decarbonization of the power sector and vehicle electrification are important steps toward reducing LC-CO2 emissions, they are insufficient. Thus, to reduce LC-CO2 emissions, including those from the manufacturing phase, the Japanese government needs to focus on decarbonizing the supply chain and extending vehicle lifetime, especially that of EVs, as well as reducing driving phase emissions.

Green synthesis of hypercrosslinked polymers for CO2 capture and conversion: recent advances, opportunities, and challenges

Hypercrosslinked polymers and the resultant carbon materials are promising platforms for CO2 capture and conversion, because of their high specific surface areas, and modifiable and accessible surface functionalities.

Influence of rice husk ash on the mechanical properties of ultra-high strength engineered cementitious composites (UHS-ECC).

Generally, UHS-ECC should consume massive cement, which is negative to its sustainability as cement production leads to 8% of global CO2 emissions. To decrease the cost of production and carbon emissions of UHS-ECC, rice husk ash was employed to replace the cement as a supplementary cementitious material in this study. Experiment results illustrate that blending rice husk ash (RHA) would decrease the fluidity of mortar. Furthermore, the green UHS-ECC shows a maximum compressive strength of 130.3 MPa at 28 days when RHA content was 20% of cement. The ultimate tensile strength of UHS-ECCs first increased and then decreased, while both tensile strain and strain energy presented an opposite tendency. At the micro-scale, if RHA content was lower than 20% of cement, incorporating RHA can significantly decreasing fiber bridging complementary energy of UHS-ECC, thus reducing pseudo strain hardening energy (PSHenergy) index, which finely agrees with the degradation of ductility of UHS-ECCs. To guarantee the features of ultra-high strength, acceptable workability, and high tensile ductility, the RHA dosage should not be in excess 20% of cement. These researched results are prospected to the contribution of pozzolanic RHA on the efficient usage of sustainable UHS-ECC.

A DFT study of CO2 electroreduction catalyzed by hexagonal boron-nitride nanosheets with vacancy defects.

In addition to providing a sustainable route to green alternative energy and chemical supplies from a cheap and abundant carbon source, recycling CO2 offers an excellent way to reduce net anthropogenic global CO2 emissions. This can be achieved via catalysis on 2D materials. These materials are atomically thin and have unique electrical and catalytic properties compared to bigger nanoparticles and conventional bulk catalysts, opening a new arena in catalysis. This paper examines the efficacy of hexagonal boron nitride (h-BN) lattices with vacancy defects for CO2 electroreduction (CO2RR). We conducted in-depth investigations on different CO2RR electrocatalytic reaction pathways on various h-BN vacancy sites using a computational hydrogen model (CHE). It was shown that CO binds to h-BN vacancies sufficiently to ensure additional electron transfer processes, leading to higher-order reduction products. For mono-atomic defects VN (removed nitrogen), the electrochemical path of (H+ + e-) pair transfers that would lead to the formation of methanol is most favorable with a limiting potential of 1.21 V. In contrast, the reaction pathways via VB (removed boron) imposes much higher thermodynamic barriers for the formation of all relevant species. With a divacancy VBN, the hydrogen evolution reaction (HER) would be the most probable process due to the low rate-determining barrier of 0.69 eV. On the tetravacancy defects VB3N the pathways toward the formation of both CH4 and CH3OH impose a limiting potential of 0.85 V. At the same time, the HER is suppressed by requiring much higher energy (2.15 eV). Modeling the edges of h-BN reveals that N-terminated zigzag conformation would impose the same limiting potential for the formation of methanol and methane (1.73 V), simultaneously suppressing the HER (3.47 V). At variance, the armchair conformation favors the HER, with a rate-determining barrier of 1.70 eV. Hence, according to our calculations, VB3N and VN are the most appropriate vacancy defects for catalyzing CO2 electroreduction reactions.

Experimental Study on the Behavior of One Part Geopolymer Concrete Using Natural Binders and Activators

The cement industry is one of the primary factors contributing to the process of global warming with a large carbon footprint. Approximately 8% of global CO2 emissions are attributed to cement. The development of cement substitute materials has advanced with the discovery of geopolymer concrete. The conventional geopolymers are two part mixes made up of an activator-containing liquid phase and an aluminum-silicate material-containing solid phase. Among the many benefits of geopolymers are their increased environmental friendliness, better workability, greater compressive strength, increased resistance to sulfate and acids, increased temperature resistance, and decreased drying shrinkage and creep. However, geopolymerization is a difficult procedure. Furthermore, there are still certain drawbacks to geopolymer concrete, such as the fact that alkaline solutions are difficult to handle and apply because they are viscous, corrosive, difficult to transport, as well as challenging to store in huge quantities. As a result, the creation of one-part geopolymer concrete gained more advantages over the traditional two part geopolymer. Solid aluminosilicate and solid alkali activator combine to form one part geopolymer concrete. The creation of one-part geopolymer concrete with natural binders is the primary goal of this research. It should be highlighted that GGBS based geopolymer concrete is challenging to make and has poor workability. As a result, various proportions of GGBS and silica fume are utilized as binders in this experiment. Powdered NaOH is utilized as alkaline activator. The mechanical properties are established by conducting necessary experiments for finding the best concrete mixture for this present work.The concrete mix with 80%, GGBS, 10% silica fume and 10% NaOH exhibits the expected quality of fresh properties and mechanical characteristics.