High Carbon Research Articles

Integrated optimization modelling framework for low-carbon and green regional transitions through resource-based industrial symbiosis

The development and utilization of bulk resources provide the basic material needs for industrial systems. However, most current resource utilization patterns are unsustainable, with low efficiencies and high carbon emissions. Here, we report a quantitative tool for resource-based industries to facilitate sustainable and low-carbon transitions within the regional economy. To evaluate the effectiveness of this tool, the saline Qinghai Lake region was chosen as a case study. After optimizing the industrial structure, the benefits of economic output, resource efficiency, energy consumption, solid waste reduction, and carbon emission reduction can be obtained. The scenario analyses exhibit disparities in different transition paths, where the carbon mitigation, economic output, and resource efficiency that benefit from optimal development paths are significantly better than those of the traditional path, indicating the urgency of adopting cleaner technology and industrial symbiosis for regional industries.

Subalpine peatland development since the Last Glacial Maximum in subtropical China: Predominantly controlled by monsoonal climate and local topography

Peatlands interact significantly with the global carbon cycle and climate changes. A comprehensive understanding of the development of peatlands is extremely important to help address future climate challenges. Here, we combine three total organic carbon content records with seven published records from subalpine peatlands in the monsoonal region of subtropical China, aiming to reveal the general pattern of peatland development since the Last Glacial Maximum (LGM) in this region. The synthesis showed that organic carbon contents significantly increased at approximately 16 cal kyr B.P. These ten records clearly display two distinct patterns since that time: pattern one showed three intervals of high carbon contents at ca. 16−12 cal kyr B.P., 9.5−7.5 cal kyr B.P. and 6−4 (or 4−1) cal kyr B.P., whereas pattern two reached the maximum in the early Holocene and remained high and relatively stable during the Holocene. Through comparison with pollen indicators and climate reconstructions, we demonstrated that local hydrology linked to monsoonal climates (especially precipitation) was the dominant factor controlling carbon accumulation and the development of subalpine peatlands since the LGM in subtropical China. However, two dynamic patterns that occurred under the same climatic conditions were attributed to the significant modulation of local topography, i.e., intermontane basin (pattern one) or montane (pattern two) settings. The hydrology and development of peatlands are functions of the changes in monsoonal climate and local site-specific topography. These findings provide a comprehensive understanding of past long-term development of peatlands under monsoonal climates.

Cross sections for the production of radionuclides induced in W targets by high energy carbon ions and protons

Cross sections for the production of radionuclides induced in W targets by high energy carbon ions and protons

Cultivated Grassland Types Differently Affected Carbon Flux Downstream of the Yellow River

Cultivated grasslands are an important part of grassland ecosystems and have been proven to be major carbon sinks, then playing an important role in the global carbon balance. The effect of cultivated grassland type (Medicago sativa, Triticum aestivum, Secale cereale, and Vicia villosa grasslands) on carbon flux (including net ecosystem CO2 exchange (NEE), ecosystem respiration (ER), and gross ecosystem productivity (GEP)) downstream of the Yellow River was studied via the static chamber technique and a portable photosynthetic system. Bare land was used as a control. The results showed that the four cultivated grassland types were mainly carbon sinks, and bare land was a carbon source. The cultivated grassland types significantly affected carbon flux. The average NEE and GEP of the grassland types were in the following order from high to low: Medicago sativa, Secale cereale, Triticum aestivum, and Vicia villosa grassland. Stepwise regression analysis showed that among all measured environmental factors, soil pH, soil bulk density (BD), soil organic carbon (SOC), and soil microbial carbon (MBC) were the main factors affecting CO2 flux. The combined influence of soil BD, SOC, and pH accounted for 77.6% of the variations in NEE, while soil BD, SOC, and MBC collectively explained 79.8% of changes in ER and 72.9% of the changes in GEP. This finding indicates that Medicago sativa grassland is a cultivated grassland with a high carbon sink level. The changes in carbon flux were dominated by the effects of soil physicochemical properties.

Early Holocene occurrence of loess in Folldal, east-central southern Norway: Identification, origin and palaeoclimatic significance

Identified for the first time in Norway, windblown yellowish-brown dust in Folldal, east-central southern Norway, fulfils physical and geochemical criteria for sensu stricto loess, including a high carbonate content. Two extant and one relict marl pond located on low-carbonate rocks are investigated. An allochthonous origin for the marl ponds is suggested and explained by the deposition of suspended clastic carbonate as loess by aeolian processes. The scattered geographical distribution of loess and the need for a calcareous source area suggest a W-SW provenance from a relict valley sandur/existing flood plain in upper Grimsdalen. The mean grain size (~22.4 µm) of the aeolian silt is in the finer range of average loess, explained by the up to 25–30 km long transport and approximately 250–300 m airborne uphill move from the suggested source area to the marl ponds. Based on age-depth modelling using 9 AMS radiocarbon dates, loess deposition occurred from ca. 10,390 to 9780 cal. yr BP (610 years). Two prominent periods of loess accumulation occurred from ca. 10,390 to 10,190 (200 years) and ca. 10,020–9950 (70 years) cal. yr BP. Loess deposition results from W-SW wintertime winds in a dry to semi-arid climate. In southern Norway, W-SW winds in winter are associated with a positive mode of the North Atlantic Oscillation (NAO). From source to deposition, the response time to erode, transport and accumulate loess is suggested to be seasonal to 1 year. An immediate increase in organic production followed loess deposition as early initiation of a warmer and wetter Holocene climatic optimum.

Comparison of microstructure, mechanical, and electrochemical performance of laser-deposited FeCrV15 alloy at varying powder feed rates

In the realm of surface modification, repair, and reinforcement of components exposed to challenging operational conditions, such as tillage tools, laser cladding stands out as an innovative manufacturing technique. Employing this additive manufacturing approach, a functionally graded material with outstanding strength and properties is incorporated to enhance the desired attributes of the base material. This comparative investigation scrutinized and assessed the microstructural characteristics, hardness, wear resistance, and corrosion behavior of high carbon ferrochrome FeCrV15 coatings fabricated at two distinct powder feed rates, namely 5 and 6 g/min, respectively. The analysis delved into how the resultant coatings' molten bead deposition, microstructural evolution, hardness, wear resistance, and corrosion resistance were influenced by the powder feed rate. Evaluation of hardness was conducted using a Vickers microhardness testing apparatus, while phase identification was accomplished utilizing an X-ray diffractometer. The morphologies of the microstructures were scrutinized employing optical microscopy and scanning electron microscopy coupled with energy dispersive spectroscopy (SEM/EDS). Furthermore, the corrosion response of the deposits in a soil–water environment was probed utilizing an Autolab potentiostat. A comprehensive assessment of the coatings' sliding wear performance was undertaken using an Anton Paar Tribometer. The findings of the study reveal that an escalation in the powder feed rate engenders heightened grain refinement within the microstructure, yielding a defect-free sample and augmenting the wear performance (with a wear rate of 2.42 × 10–6 mm3/N/m for sample B, surpassing 2.39 × 10–5 mm3/N/m for sample A and outstripping 1.72 × 10–3 mm3/N/m for the steel substrate). Additionally, the corrosion resistance is enhanced (with a corrosion rate of 0.0032 mm/yr for sample B, surpassing 0.0036 mm/yr for sample A, which, in turn, exceeds 0.1168 mm/yr for the steel substrate) in the case of sample B.

How does climate change risk affect energy poverty? International evidence.

Based on cross-country data from 2002 to 2019, we explore the impact of climate change risk (CCR) on energy poverty (EP), and the moderating role in the CCR-EP nexus is also discussed. The empirical results suggest that CCR can exacerbate EP, especially for rural areas. Moderating effect analysis shows that financial development, technological innovation, and adaptation readiness can modify the negative impacts of CCR on EP to some extent. Moreover, the impact of CCR on EP is heterogeneous, demonstrating that CCR is more likely to exacerbate EP in countries with low economic development, low economic freedom, high carbon intensity, and the Africa region. Our findings emphasize the challenge of balancing EP alleviation with climate change response and provide the policy guidance to promote coordinated development of CCR management and energy supply security.

Mesophase pitch-based high performance carbon fiber production using coal extracts from mild direct coal liquefaction

Mild direct coal liquefaction (autogenous pressure, no catalyst, no H2 gas) of Springfield coal in fluid catalytic cracking decant oil is shown to effectively produce coal extract precursors to spinnable mesophase pitch. This work demonstrates that the coal extract can be thermally treated to obtain mesophase pitch in a facile one-step process, bypassing the production of an intermediate isotropic pitch. Furthermore, the presence of 25 wt.% coal in the initial slurry can increase the yield to mesophase pitch nearly twofold and yield to carbon fiber by approximately 70%. The coal extract-derived mesophase pitch was melt-spun and heat treated to produce carbon fiber with graphitic texture, high modulus (>400 GPa) and tensile strength up to 943 MPa. Overall, this work demonstrates that coal can be effectively utilized to markedly amplify the mesophase pitch and carbon fiber yield from fluid catalytic cracking decant oil by relatively simple processing, while conserving utility as a precursor to high performance carbon fiber and potentially other high value graphitic products.

Discovery of the first hydrothermal field along the 500-km-long Knipovich Ridge offshore Svalbard (the Jøtul field)

Oceanic spreading centers north of Iceland are characterized by ultraslow spreading rates, and related hydrothermal activity has been detected in the water column and at the seafloor along nearly all ridge segments. An exception is the 500-km-long Knipovich Ridge, from where, until now, no hydrothermal vents were known. Here we report the investigation of the first hydrothermal vent field of the Knipovich Ridge, which was discovered in July 2022 during expedition MSM109. The newly discovered hydrothermal field, named Jøtul hydrothermal field, is associated with the eastern bounding fault of the rift valley rather than with an axial volcanic ridge. Guided by physico-chemical anomalies in the water column, ROV investigations on the seafloor showed a wide variety of fluid escape sites, inactive and active mounds with abundant hydrothermal precipitates, and chemosynthetic organisms. Fluids with temperatures between 8 and 316 °C as well as precipitates were sampled at four vent sites. High methane, carbon dioxide, and ammonium concentrations, as well as high 87Sr/86Sr isotope ratios of the vent fluids indicate strong interaction between magma and sediments from the Svalbard continental margin. Such interactions are important for carbon mobilization at the seafloor and the carbon cycle in the ocean.

Unveiling 4500 years of environmental dynamics and human activity at Songo Mnara, Tanzania

Coastal East Africa has undergone massive transformations through the Late Holocene, with a combination of changes in sea level, increasing human settlement, and ensuing use of coastal resources. A comprehensive multi-proxy analysis, including pollen, phytolith, charcoal, stratigraphy, particle size, and geochemical data from sedimentary cores extracted from mangrove ecosystems combined with soils from archaeological contexts, provided valuable insights into vegetation dynamics, environmental changes, and human interactions within the mangrove ecosystem of Songo Mnara Island, Tanzania over the last 2590 BCE (4540 cal yr BP). The bottommost layers indicate a lack of vegetation, as deduced from the presence of coral rags and high calcium and carbonate content, possibly due to high mid-Holocene sea-level. Evidence of mangrove taxa suggests a decrease in sea level, enabling the establishment of mangroves from around 2590 BCE. A brief period of sea-level rise occurred between 90 BCE and 320 CE before sea-level fell until 1570 CE. Significant evidence of human activity is recorded from around 1400 CE indicated by increased charcoal, crop phytoliths, and evidence of marine resource utilisation. The timing of this human-environment interaction is also linked to the time of lower sea level. However, there was evidence suggesting human abandonment of the island from around 1500 CE. This coincided with a subsequent rise in sea levels and potentially prolonged drought conditions spanning from 1570 to 1700 CE. These factors likely contributed to a shortage of food resources in the area, impacting both agricultural practices due to the scarcity of natural freshwater and the accessibility of marine food resources. From 1700 CE to the present, fluctuations in sea level have been observed, with a signal of recent sea-level rise in tandem with shifts in mangrove, terrestrial herbaceous taxa and fire activity.The low sedimentation rates within mangrove areas suggest that the mangroves on Songo Mnara Island may not keep pace with the current rate of sea-level rise.

Low-Carbon Ecological Tea: The Key to Transforming the Tea Industry towards Sustainability

The realization of the value of ecological products has led to an economic means for reducing carbon emissions in China. Tea is one of the most important cash crops and one of the most popular beverages in the world. Due to the complex the tea industrial chain, it is considered to be an industry with high carbon emissions. Ecological tea products with low-carbon attributes can be considered a linkage of ecology, economy, and society. Based on this, this paper presents research on low-carbon ecological tea (LCT). Herein, we construct the formational logic of low-carbon ecological products, explore the connotations of LCT, and form a conceptual pathway for realizing LCT to contribute to climate change mitigation and adaptation. This paper starts from the upstream, midstream, and downstream of the industrial chain; it establishes three value realization pathways that keep, as a priority, the promotion of ecological industrialization, focus on restoration to improve the ecology of the industrial chain, and innovate technology to expand the industrial chain. The pathways are a set of low-emission production solutions that use techniques to enhance carbon sequestration in soil, reduce the use of fertilizers and pesticides, and help shift to clean energy from low-emission sources in the stages of plantation, processing, and distribution. In the process of realizing LCT, the government plays an important role, and its support and guidance are needed. Based on stakeholder theory, this paper builds an implementation mechanism that focuses on the micro perspective (users, organizations), integrates the mesoscopic perspective (industry), and relies on the macro perspective (government).

High stiffness 3D-printed continuous pitch carbon fiber reinforced polymer composites

This study presents a method for 3D printing very high stiffness pitch-based carbon fiber (CF) reinforced polylactic acid (PLA) composites using a modified open-source 3D printer. The fused filament fabrication (FFF) technique was used to fabricate the samples with alternating layers of PLA and PLA-coated pitch CF. The tensile Young’s modulus of the 3D-printed composite samples was measured to characterize the effect of different grades and volume fractions of pitch CF on the behaviour of the printed composites. Three grades of pitch CF which have different Young’s modulus were used with volume fractions ranging from 2.4 to 8.4%. Tensile tests showed that the K1392U CF reinforced composite with a 7.3% volume fraction demonstrated the highest improvement in Young’s modulus of 850% compared to neat 3D-printed PLA. This improvement is notably higher than any previous 3D-printed carbon-based composites at a relatively low volume fraction of CF. Statistical analysis showed increased Young’s modulus in all of 3D-printed composite samples tested. The experimental values were compared to the Halpin-Tsai model and suggest that some degree of fibre breakage occurred during the 3D printing process owing to the relative stiffness of the pitch-based fibers. Future directions and suggestions for process improvements are discussed.

The multi‐stage gasification process of low‐rank coal samples from gravity separation process

AbstractThe separation process is a well‐established method for beneficiation technologies of low‐rank coal, especially in the case of utilization in the thermochemical processes. In this study, three coal samples, including the original low‐rank coal sample and two coal samples (C1 and C2) from the gravity separation process of the original coal sample, were gasified in a multi‐stage gasification process at the gasification temperature of 900°C and the steam‐to‐carbon (S/C) ratio of 1.00 and 1.25. The separation process led to a significant improvement in the quality of coal samples. This improvement is particularly characterized by a higher carbon and volatile fractions and a lower ash content compared with the original coal. This could be the main reason for the higher gasification performance in the case of the experiment of C1 and C2 coal samples. The volume of syngas obtained from gasification experiments of C1 and C2 samples increased between 1.3 and 1.5 times that of the original coal sample. At all S/C ratios and 900°C, the gasification experiment of the C2 sample produced the highest produced gas yield followed by the gasification experiment of the C1 sample. From the chemical point of view, the produced gas had an H2/CO ratio close to the desired ratio of 2.00, which is suitable for chemical synthesis processes. In the case of C1 sample experiments, the H2/CO ratios were 2.11 and 2.18 at S/C ratios of 1.00 and 1.25, respectively. For the experiments of the C2 sample, the H2/CO ratio reached 1.88 and 2.00 at S/C ratios of 1.00 and 1.25, respectively.

Design of Experiments for Optimized Synthesis of Carbon‐Supported Ni Nanoparticles: A Green Chemistry Approach

AbstractMetallic nickel nanoparticles supported on a high specific surface area carbon powder were synthesized by a classical polyol method without external reducing agent or surfactant. Ni/C materials were characterized by TGA, XRD, cyclic and linear voltammetry. To decrease the number of experiments, a Taguchi design of experiments (DoE) was implemented and the effects of different synthesis parameters (nature of the nickel salt, loading of Ni on carbon, nNaOH/nNi ratio and reaction time at reflux) on different responses (crystallite size, electrochemically active surface area and current density for the glucose oxidation reaction at 1.5 V) determined. Optimization of parameter values for decreasing the crystallite size down to 14 nm was achieved using the DoE. For the other responses, strong interactions between parameters avoided straightforward optimization of parameter values. However, some trends could be drawn from the experimental matrix showing that the synthesis of a catalyst loaded with only 10 wt% Ni, with NiCl2 as precursor salt, with a nNaOH/nNi ratio of 6 for 80 minutes at reflux was a good compromise between atom, time and energy savings, costs efficiencies, and electrochemically active surface area and catalytic activity towards the glucose oxidation reaction, particularly in terms of mass activity.

Corrigendum: Immobilisation of anaerobic digestate supplied nitrogen into soil microbial biomass is dependent on lability of high organic carbon materials additives

Corrigendum: Immobilisation of anaerobic digestate supplied nitrogen into soil microbial biomass is dependent on lability of high organic carbon materials additives

Liquid Chromatography Coupled to Isotope Ratio Mass Spectrometry Expanded to Include Organic Mobile Phases.

Current commercially available liquid chromatography coupled to isotope ratio mass spectrometry systems (LC-IRMS) oxidize all eluent and thus can only operate with all-aqueous mobile phases, limiting their application to a small subset of analytes and mixtures that can be separated without organic solvents. We report a novel rotating-catalytic disc desolvation device with subsequent laser-activated photocatalytic analyte combustion to create CO2 for high precision carbon isotope ratio measurements compatible with both aqueous and organic liquid mobile phases. Sucrose, glucose, androsterone, or androsterone acetate in 20% and 50% H2O-CH3OH solutions were introduced by flow injection to the interface to IRMS for sugars and steroids, respectively. Sucrose δ13CVPDB linearity was excellent over 1-10 μg (33-655 nmol C) injections, using IRMS compatible He/1%O2 oxidation gas. The limit of precise isotope analysis (LOIA) of δ13CVPDB was 1 μg (35 nmol C) for sucrose and 10 μg (655 nmol C) for androsterone with average precisions of SD(δ13C) ± 0.8‰. Calibration was performed with and bracketed the δ13CVPDB isotope ratio range using androsterone-acetate and glucose. With further development to improve sensitivity and application to chromatography, the prototype proof-of-principle LC-IRMS shows promise to resolve a major drawback in current LC-IRMS systems and may open LC-IRMS to many more compounds than currently possible.

Reinforcement learning-driven proximal policy optimization-based voltage control for PV and WT integrated power system

The depletion of conventional fuel reserves and the high carbon emissions have alarmed the energy sector drivers. The integration of renewable energy resources (RERs) towards power system transformation is an obvious approach for a new-zero future. However, this integration also brings challenges in terms of voltage stability and power losses due to the variable output of RERs. To address these challenges, this work proposes a novel approach utilizing photovoltaic (PV) inverters and static var compensators (SVCs) for reactive power control in power distribution networks (PDNs). It enhances voltage stability and minimizes power losses. The proposed study deploys a proximal policy optimization (PPO) algorithm for real-time communication and control between reactive power devices. Performance evaluation was made on an IEEE-33 Bus system to demonstrate the effectiveness of the proposed scheme in integrating RER-based distributed generators (DGs). The proposed system achieved 68 % voltage control, keeping the voltage within a certain range of ±5 % while minimizing power losses. The proposed system also reduced the voltage out-of-control ratio to 0.044, which indicates minimum voltage deviation from the standard value. The proposed study provides a promising solution for controlling the voltage of DGs integrated PDN, which can potentially enhance the efficiency and reliability of the power system.

Feasibility and greenhouse gas emissions of timber structures in solar photovoltaic carport construction

This contribution focuses on reducing the greenhouse gas (GHG) emissions of solar photovoltaic (PV) carport structures by replacing carbon-intensive steel with a wood-based material. There is a growing need for PV systems that are suitable for urban environments where the lack of roof spaces and open land limits the use of traditional PV installations. To date, PV carports have been mainly constructed with steel, which has a high carbon footprint and can be considered aesthetically unattractive. Wood structures, on the other hand, could act as carbon storage and thus reduce the GHG emissions of the whole system. Emissions and costs of supporting structures for PV systems have received very little attention, and there is virtually no literature specific to them. This study compares wood-based glued laminated timber (GLT) structures with conventional steel structures by investigating the GHG emissions and economic feasibility. The simulated 485 kWp system with wooden structures yielded base-case lifetime GHG emissions of 11.3 g CO2 eq/kWh in Turku Finland (60°N), and 8.2 g CO2 eq/kWh in Dijon France (47° N), representing a 48% lower value compared to systems with steel structures. Furthermore, wooden structures were competitive in terms of costs, being approximately 25% cheaper. Thus, wooden structures provide a very attractive way to make infrastructure integrated PV more sustainable.

3D intrusions transport active surface microbial assemblages to the dark ocean

Subtropical oceans contribute significantly to global primary production, but the fate of the picophytoplankton that dominate in these low-nutrient regions is poorly understood. Working in the subtropical Mediterranean, we demonstrate that subduction of water at ocean fronts generates 3D intrusions with uncharacteristically high carbon, chlorophyll, and oxygen that extend below the sunlit photic zone into the dark ocean. These contain fresh picophytoplankton assemblages that resemble the photic-zone regions where the water originated. Intrusions propagate depth-dependent seasonal variations in microbial assemblages into the ocean interior. Strikingly, the intrusions included dominant biomass contributions from nonphotosynthetic bacteria and enrichment of enigmatic heterotrophic bacterial lineages. Thus, the intrusions not only deliver material that differs in composition and nutritional character from sinking detrital particles, but also drive shifts in bacterial community composition, organic matter processing, and interactions between surface and deep communities. Modeling efforts paired with global observations demonstrate that subduction can flux similar magnitudes of particulate organic carbon as sinking export, but is not accounted for in current export estimates and carbon cycle models. Intrusions formed by subduction are a particularly important mechanism for enhancing connectivity between surface and upper mesopelagic ecosystems in stratified subtropical ocean environments that are expanding due to the warming climate.

Water extractable carbon and nitrogen across vegetated and non-vegetated coastal habitats

Many coastal ecosystems have a high carbon (C) and nitrogen (N) accumulation capacity. Extractable C and N have been shown to be useful indicators to assess changes in soil C and N in terrestrial systems but have not been widely used in coastal habitats. Here, we quantified cold and hot water extractable organic C (cweC, hweC) and N (cweN, hweN) and determined specific ultraviolet absorbance (SUVA254) to evaluate how water extractable C and N concentration and chemistry change along the transition from mangrove (vegetated) to tidal flat (non-vegetated) and with sediment depth. Sediment cores (20 cm depth) were collected along transects in a muddy (29-46 % clay+silt, Snells Beach) and sandy (8-11% clay+silt, Hobson Bay) estuary in the Auckland region, New Zealand. Cold water exactable C and N concentrations were similar in the muddy and sandy estuary (7-173 μg C g-1 soil; 1-32 μg N g-1 soil). However, cweC and cweN made up a larger proportion of sediment C and N concentration at the sandy estuary. The hweC and hweN concentrations were significantly higher in the muddy (240-2440 μg C g-1 soil; 25-244 μg N g-1 soil) than sandy estuary (50-960 μg C g-1 soil; 6-119 μg N g-1 soil) suggesting a higher release of C and N from the muddy estuary with organic matter rich sediments. Habitat had a strong effect at both sites with extractable C and N concentrations being higher in mangroves compared to tidal flat. The C:N ratios and SUVA254 values of cweC tended to be lower than hweC across all habitats in both estuaries, suggesting a higher proportion of algal-derived organic matter and a lower proportion of aromatic molecules. Our findings demonstrate that water extractable C and N provide valuable insights into the quality and drivers of C and N in coastal habitats.