Source Of Carbon Dioxide Research Articles

The efficacy of carbon molecular sieve and solid amine for CO2 separation from a simulated wet flue gas by an internally heated/cooled temperature swing adsorption process

Considering that most sources of carbon dioxide (CO2) emissions are also waste heat sources, CO2 recovery using self–generated low–temperature waste heat is desirable. This study examines CO2 enrichment and recovery via a temperature swing adsorption (TSA) process. The low–temperature heating–driven TSA process requires an alternative regeneration method to conventional air heating to avoid dilution of the desorbed CO2, and to apply it to actual gas, using an adsorbent that does not lose its CO2 adsorption capacity because of coexisting water vapor is necessary. Zeolites tested in our previous study lose their CO2 adsorption ability under a humid feed gas and a low–temperature regeneration condition. For the former, efficacy of an internally heated and cooled adsorbent–packed fin–coil heat exchanger has been confirmed. This study thus attempts to overcome the latter issue by employing carbon molecular sieve (CMS) and solid–supported polyethyleneimine (PEI) as CO2 adsorbents. The effects of moisture in the inlet gas on the separation performance of adsorbents were investigated. The study reveals that PEI required moisture to extend for CO2 adsorption, and CO2 separation performance increased with higher humidity. PEI can produce the desorbed gas with a CO2 concentration of ∼ 45 % and a recovery ratio of ∼ 70 % from feed gas (CO2 concentration of ∼ 10 %) at a dew point temperature of 15 °C. Conversely, the CMS separation performance is almost independent of humidity. The desorbed gas of CMS indicates a CO2 concentration of only ∼ 30 % and a recovery of ∼ 30 %. The flow of the volumetric desorbed gases and the CO2 concentration rate indicates that CMS has the potential for reducing heat consumption by shortening the regeneration time because most of the CO2 desorbs during the early regeneration step. For increasing the concentration of recovered CO2, a severe control valve is required to eliminate the desorbed nitrogen (N2) accompanied by CO2. In contrast, CO2 desorption from PEI is slower than that in CMS, and PEI needs a relatively longer regeneration time.

Analysis Of NOx, SO2, PM10, & CO Emission Loads From Motorized Vehicle at Collector’s Road Makassar City Using Tier 2 Method

The biggest factor in the global reduction in air quality in large cities is the transportation industry. This is due to the molecules that gasoline, the fuel used in the transportation sector, emits, including carbon monoxide (CO), nitrogen oxide (NOx), sulfur dioxide (SO2), and CO2 (carbon dioxide), as well as hydrocarbons (HC), which are sources of carbon dioxide. of emissions of air pollutants An imbalance results from the rising motorized vehicle sales from year to year combined with poor traffic conditions. In urban locations, several collector roads—the hub of community activity—often encounter congestion, especially during rush hours. Because of the pollution these motorized vehicles produce, the congestion they induce has a negative effect on the environment. This study aims to determine the daily and yearly emission loads for the parameters of NOx, SO2, PM10, and CO produced by motor vehicles with three types of vehicles, namely motorcycles (MC), Light Vehicles (LV), which are divided into the Sedan category, Minibus, Taxi, Public Transportation, then Heavy Vehicles (HV), which are divided into Pick-up, Jeep, micro bus, big bus, 2 axles truck, and 3 axles trucks categories, on Collector Street in Makassar City utilizing the Tier 2 method and show the form for mapping the distribution of NOx, SO2, PM10, and CO emissions from motor vehicles on Collector Street in Makassar City using the Geographic Information System application. The findings indicated that Jalan Hertasning produced the highest emission load from the NOx, SO2, PM10, and CO parameters. This is because of the significant role that Hertasning Road plays in Makassar City’s urban road network, which results in a high volume of daily vehicle traffic on this road section. The CO parameter, which accounts for 104041.57 tons of the total emission load from motor vehicles on Jalan Hertasning, per year.

Investigation of Natural Condition in Urban Landscapes of Plain Areas Based on GIS

Cities are major sources of carbon dioxide, nitrogen oxides and other toxic gases. Strong development of transport and industry is a major factor in the deterioration of the environmental situation in the city and surrounding areas. From this point of view, the topic we have studied is also very relevant. We have analyzed the current situation of the city of Imishli, located in the central arid area of the Republic of Azerbaijan – Mil plain, on the basis of modern technologies and have studied the previous situation on the basis of funds and literature, then have compared all the results. The factors affecting the environment in the city have been comprehensively analyzed. Density of constructions, population dynamics, the relationship between population growth and area expansion, the dynamics of vegetation cover, the impact of industrial and agricultural enterprises, transport on the atmosphere, hydrosphere and biosphere were studied.

Attribution of individual methane and carbon dioxide emission sources using EMIT observations from space.

Carbon dioxide and methane emissions are the two primary anthropogenic climate-forcing agents and an important source of uncertainty in the global carbon budget. Uncertainties are further magnified when emissions occur at fine spatial scales (<1 km), making attribution challenging. We present the first observations from NASA's Earth Surface Mineral Dust Source Investigation (EMIT) imaging spectrometer showing quantification and attribution of fine-scale methane (0.3 to 73 tonnes CH4 hour-1) and carbon dioxide sources (1571 to 3511 tonnes CO2 hour-1) spanning the oil and gas, waste, and energy sectors. For selected countries observed during the first 30 days of EMIT operations, methane emissions varied at a regional scale, with the largest total emissions observed for Turkmenistan (731 ± 148 tonnes CH4 hour-1). These results highlight the contributions of current and planned point source imagers in closing global carbon budgets.

Arctic-boreal lakes of interior Alaska dominated by contemporary carbon

Northern high-latitude lakes are critical sites for carbon processing and serve as potential conduits for the emission of permafrost-derived carbon and greenhouse gases. However, the fate and emission pathways of permafrost carbon in these systems remain uncertain. Here, we used the natural abundance of radiocarbon to identify and trace the predominant sources of methane, carbon dioxide, dissolved inorganic and organic carbon in nine lakes within the Yukon Flats National Wildlife Refuge in interior Alaska, a discontinuous permafrost region with high landscape heterogeneity and susceptibility to climate, permafrost, and hydrological changes. We find that although Yukon Flats lakes primarily process young carbon (modern to 1290 ± 60 years before present), permafrost-derived carbon is present in some of the sampled lakes and contributes, at most, 30 ± 10% of the dissolved carbon in lake surface waters. Apportionment of young carbon and legacy carbon (carbon with radiocarbon age ⩾5000 years before present) is decoupled among the dissolved inorganic and organic carbon species, with methane showing a stronger legacy signature. Our observations suggest that permafrost-thaw-related transport of carbon through Yukon Flats lacustrine ecosystems and into the atmosphere is small, and likely regulated by surficial sediments, permafrost distribution, wildfire occurrence, or masked by contemporary carbon processes. The heterogeneity of lakes across our study area and northern landscapes more broadly cautions against using any one region (e.g. Yedoma permafrost lakes) to upscale their contribution across the pan-Arctic.

Environmental performance of nonthermal plasma dry and conventional steam reforming of methane for hydrogen production: Application of life cycle assessment methodology

The environmental performance of nonthermal plasma assisted dry reforming of methane (NTP-DRM) for hydrogen production from methane rich natural gas is investigated and compared with the current state of the art steam reforming technology through a cradle-to-gate life cycle assessment (LCA). The NTP-DRM technologies studied in this analysis include dielectric barrier, microwave, and pulsed plasma discharges. Due to the level of technology the study is considered as the prospective LCA of selected types of NTP-DRMs for hydrogen production. Of these, the NTP-DRM using microwave and pulsed plasma presented better environmental performance. The impact categories include midpoints levels applying TRACI 2.1 and AWARE for the water scarcity, using ecoinvent 3.8 and US NETL databases. The scenario analysis regarding carbon dioxide, electricity, and natural gas sources, revealed the highly dependency of NTP-DRMs technologies environmental performance to the energy efficiency of the processes. In terms of steam reforming of methane (SRM) despite the main contribution of steam use in the technology environmental performance, the uncertainty analysis showed higher sensitivity to natural gas input. Investigation showed that using renewable energy sources can have significant improvement regarding NTP-DRMs environmental performance and specifically global warming potential. Accordingly, at their current reactant conversion and product selectivity reaching the energy use of eV per molecule of reactant equal or less than 2, can be a proper target for the studied best case NTP-DRM to make their environmental behavior competitive with the state-of-the-art SRM technologies.

The development of global power-to-methane potentials between 2000 and 2020: A comparative overview of international projects

In recent times, electrification has become the most important means for decarbonization. One of the most pressing challenges to be addressed is the large-scale and long-term storage of electricity from renewable sources. By the utilization of the significant storage capacities of natural gas networks, power-to-methane technology using electrolysis offers the storage option most compatible with current electricity systems. Based on and complementing the IEA's hydrogen production database, the study compiled a database of power-to-methane projects launched globally between 2000 and 2020, also comparing these projects. The aim of the research was to examine the temporal and spatial distribution of international projects and their electrolysis technologies, types of methanation, carbon dioxide sources and utilizations of the final product. These analyses are important because it was these project factors, analyzed during the research, that best describe the synthetic methane production initiatives launched so far. The innovative importance of the research is that these aspects can be taken into account to establish the real contribution potentials of power-to-methane technology to decarbonization, especially in a changing policy and regulatory environment that seeks to accelerate its process.

Carbon dioxide release from retrogressive thaw slumps in Siberia

Thawing of ice-rich permafrost soils in sloped terrain can lead to activation of retrogressive thaw slumps (RTSs) which make organic matter available for decomposition that has been frozen for centuries to millennia. Recent studies show that the area affected by RTSs increased in the last two decades across the pan-Arctic. Combining a model of soil carbon dynamics with remotely sensed spatial details of thaw slump area and a soil carbon database, we show that RTSs in Siberia turned a previous quasi-neutral ecosystem into a strong source of carbon dioxide of 367 ± 213 gC m-1 a-1. On a global scale, recent CO2 emissions from Siberian thaw slumps of 0.42 ± 0.22 Tg carbon per year are negligible so far. However, depending on the future evolution of permafrost thaw and hence thaw slump-affected area, such hillslope processes can transition permafrost landscapes to become a major source of additional CO2 release into the atmosphere.

Multi-objective optimisation of a carbon capture and sequestration supply chain under seismic risk constraints. A case study considering industrial emissions in Italy

Carbon capture and sequestration represents a key decarbonisation option, particularly for large-scale fossil-based industry sectors (e.g. cement, steel, and oil refineries). Carbon capture and sequestration networks have nonetheless raised concerns regarding the possibility of leakages, especially in high seismic-risk regions.In this study, a multi-objective mixed integer linear programming modelling framework is developed to minimise the cost and the seismic risk associated with the deployment of a carbon capture and sequestration infrastructure in Italy. The most significant industrial carbon dioxide sources (23 cement plants, 7 refineries, and 2 steel mills) are included in the model. The optimisation variables comprise capture technologies, transport options (onshore vs. offshore pipelines), and the choice of onshore and offshore deep saline aquifers for sequestration.Three carbon dioxide emission reduction targets (20 %, 50 %, 80 %) are considered to assess the optimal design configurations in terms of either cost or seismic risk. Results show that the seismic risk optimum determines an increase in total cost ranging between 10 % (for an 80 % reduction target) and 65 % (for a 20 % reduction target) with respect to the economic optimum. Considering only offshore sequestration leads to cost increase between 20 % and 30 % with respect to solutions accepting onshore sequestration, too. Conversely, cost-optimal infrastructures have a seismic risk that is between 1.5 and 18 times higher than that of the safest chains.

Computation of the environmental performance of ready-mix concrete for reducing CO2 emissions: A case study in Egypt

Concrete is one of the largest sources of carbon dioxide (CO2) worldwide due to the use of cement as its main component. The share of CO2 from cement industry is about 7%. There is a growing need for ways and methods to systematically identify, asses, modify, the cement production process for emission reduction. In line with Egypt commitment to climate change in the COP27, a framework is designed for the assessment of the cement plant. The aim of this paper is to investigate and calculate the CO2 emissions from a building in the New Egyptian Administrative Capital in the area of R5 using ready mix concrete. This study used compiled data of emission factors from Titan Egypt cement plant as the producer of cement in R5. The essential data needed for the calculations were collected from the literature with the guidance of the Intergovernmental Panel of Experts on Climate Change (IPCC) Guidelines for National Greenhouse Gas Inventories, the Cement Sustainability Initiative (CSI) of the World Business Council for Sustainable Development (WBCSD) as well as the inventory sustainability reports guided by the Egyptian Environmental Affairs Agency (EEAA). This is done on two parts: the calculation of CO2 total emissions of the baseline scenario and the second part is a computation of the emissions based on the alternative use of different categories such as raw materials, fuel consumption, energy efficiency, transportation, and water consumption. A comparison between the baseline and the alternative case took place to compute the percentage of reduction in emissions from concrete. The study findings are promising. The total amount of emissions from the concrete used in this project is about 3114.49 tons. By using the mitigation measures, there is a potential reduction in the total CO2 emissions of the building by calculations is concluded to be around 5.94%.

Sources and controls of greenhouse gases and heavy metals in mine water: A continuing climate legacy

Water pollution arising from abandoned coal mines, is second only to sewage as a source of freshwater pollution and in coalfield catchments mine water can be the dominant pollutant, with oxidised iron smothering the bed of receiving rivers. This study measured greenhouse gases in mine water outflows from sixteen sites across the Midland Valley in Scotland. Radiogenic and stable carbon isotopes measurements (Δ14C and δ13C) were used to determine the sources of both methane (CH4) and carbon dioxide (CO2) produced within the flooded mine environment. Concentrations of CH4-C ranged from 20 to 215 μg l−1 and CO2-C from 30 to 120 mg l−1, with CO2 accounting for 97 % of the mine water global warming potential. Methane origins included 51 % modern biogenic, 41 % thermogenic and 8 % from hydrogenotrophic methanogenesis of coal. The most significant inverse impact on biogenic CH4 concentrations was sulphate, most likely due to sulphate reducing bacteria outcompeting methanogens. Carbon dioxide origins included 64 % from the dissolution of limestone, 21 % from terrestrial organic carbon and 15 % from coal. The limestone derived CO2 was positively correlated with high sulphate concentrations, which resulted in sulphuric acid and caused the dissolution of carbonate from limestone. The mine waters experienced significant carbonate buffering becoming only slightly acidic (pH 6–7), but with significant loss of inorganic carbon. The mine waters had low dissolved oxygen (6–25 %) and high dissolved iron (2 to 65 mg l−1) and manganese (0.5 to 5 mg l−1) concentrations. Dissolved greenhouse gases from abandoned mines were estimated as 0.27 +0.31−0.18% of Scotland's global warming potential. This novel work has contributed information about the sources and controls of greenhouse gas fluxes in mine waters and identified the need to quantify and report this emissions term.

HOW THE INCORPORATION OF 14C IN LEAD WHITE MAKES ITS ABSOLUTE DATING POSSIBLE

ABSTRACT Known as lead white, lead carbonates were used as white pigment or cosmetics from the 4th century BC to the 20th century AD. Lead white was produced by the corrosion of metallic lead by vinegar and horse manure up to the 19th c. In order to document the incorporation of carbon in the corrosion mechanism, lead carbonates were produced in the laboratory under monitored experimental conditions using materials with different isotope signatures in 14C and 13C. Six experimental setups were defined combining vinegar, acetic acid, horse manure and fossil CO2 gas. The corrosion products were characterized by X-ray diffraction. 14C content and δ13C values of the initial reactants and the final products were measured by accelerator and isotopic ratio mass spectrometry (AMS and IRSM). The reaction between lead and vinegar or acetic acid resulted in lead acetates with a carbon isotopic signature close to that of the corrosive reagent. In the presence of CO2, the carbonatation reaction occurred and the cerussite produced had a predominant 14C signature of the carbon dioxide source. These experiments demonstrate that the CO2 produced by horse manure fermentation is incorporated into the corrosion products, allowing the absolute dating of lead white by the radiocarbon method.

Machine learning reveals the effects of drivers on PM2.5 and CO2 based on ensemble source apportionment method

Air pollution and climate change are currently common global concern issues. Understanding the main pollution sources of fine particulate matter (PM2.5) and carbon dioxide (CO2), and the drivers that accelerate their concentrations can provide novel insights into the co-benefits of air-quality improvement and climate change mitigation. Hence, in this study, we conducted source apportionment of PM2.5 and CO2, and obtained impacts of common sources on PM2.5-CO2 using an ensemble source apportionment method. Then, machine learning (ML) methods were utilized to study the effects of different drivers (including main pollution sources and meteorological factors) on PM2.5 and CO2. The results demonstrate that coal combustion (40%), vehicle exhaust (37%), and industrial emissions (23%) were the main common sources of PM2.5 and CO2. Controlling the combustion of fossil fuels and long-term vehicle electrification still hold significant importance for reducing pollutions and carbon emissions. The results of data-driven ML models show that temperature had the highest effect among meteorological factors, reflecting the seasonal changes of CO2 and PM2.5. The study provides a feasible framework for exploring co-benefits of clean air policies on greenhouse gas emissions based on online observation dataset.

Reversible decentralized ventilation: Experimental determination of efficiency by carbon dioxide level

We studied decentralized ventilation devices based on a regenerative heat exchanger with a reverse mode of operation. These devices are capable of recovering up to 90% of the heat used for ventilation of premises. They are a cheaper alternative to central units, and can solve the problem of high heat consumption for ventilation of buildings. Such devices are of little use in practice, since their efficiency concerning providing the required air exchange is poorly studied. The reverse mode of operation is not typical for room ventilation, since the same device constantly changes its purpose between supply and exhaust, which constantly changes the air distribution pattern in the room and can affect the efficiency of dilution and removal of harmful substances. Taking this fact into account makes the study original. The aim of the study is to experimentally determine the efficiency of ventilation in the premises of civil buildings when using such devices. The efficiency criterion was the level of carbon dioxide concentration in the room with a specified limit value of 1000 ppm. People were the source of carbon dioxide. Ventilation was represented by two decentralized devices. The experiment consisted in determining the level of carbon dioxide concentration in natural conditions with a different number of people in the room and different ventilation performance. The results of the experiment were verified by analytical determination of the level of carbon dioxide in the room. As a result of the experiment, dependences of changes in CO2 concentration over time were obtained when one, two and five people were in a room with and without ventilation. To ensure the level of carbon dioxide concentration below the limit (1000 ppm), the required ventilation capacity for one person was 40 m3/h, for two people – 80 m3/h, for five people – more than 160 m3/h. The results allow us to make conclusions about the efficiency of decentralized ventilation devices with reversible mode for premises with a small number of people.

High-Temperature Co-Electrolysis and Degradation by Oxidized Trace Contaminants in Feed Gases

The transformation of our energy system will likely require the indirect electrification of the sectors heating, chemical industry and mobility by power-to-X processes, because not all processes can easily use electrical power directly. The high-temperature co-electrolysis using solid-oxide cells (SOCs) can produce syngas compositions desired by the downstream power-to-X process without the need of a reverse water-gas shift reactor and is therefore particularly well suited to produce synthesis gas as feedstock for various power-to-fuel and power-to-chemicals processes. Besides, a coupling of heat-producing downstream processes would increase system efficiency significantly.1 Besides the intrinsic degradation processes of the cells (e.g. nickel migration) and stacks (e.g. contact deterioration) any additional processes triggered by impurities in the feed gases are of relevance for any technical applications. Under certain circumstances, impurities can be introduced by Balance of Plant (BoP) components like the steam generators or preheaters that can release silicon species.2 Also, the feed gases themselves may contain harmful substances. This poisoning effect must be taken into account, because economically gases of lower qualities are preferred as purification steps increase the costs of the syngas. Depending on the exact source of carbon dioxide (CO2) the supplier uses, it contains different secondary components, of which sulfur species are of particular concern. In contrast to fuel-cell mode operation, in electrolysis mode operation hydrogen sulfide (H2S) is not the most likely candidate, but sulfur dioxide (SO2). The reasons for this is that CO2 may be obtained from combustion processes and that hydrogen sulfide is not stable in the atmosphere but has a short half-life time.Therefore, understanding the influence of SO2 contained in the supplied carbon dioxide on the performance of the co-electrolysis is of great importance. There is substantial knowledge about the impact of H2S in feed gases in fuel-cell mode, but the impact of sulfur dioxide in electrolysis mode is not as well investigated. Skafte et al. reported a severe effect in CO2 electrolysis with as low as 20 ppb H2S.3 In the context of this application, the relevant sulfur species present in the feed gases will be SO2. It should be noted, that the heterogenous reduction of SO2 with hydrogen or carbon monoxide is catalyzed by oxides with oxygen vacancies and mobility like CeO2 or YSZ and facilitated by the presence of transition metals.4 Intermediary steps and products beside H2S can include significant amounts of elemental S and COS and the formation of sulfided nickel seems likely. The formation of these products depends on the exact reaction conditions, e.g. temperature, H2/SO2 ratio, steam content, which makes the situation more complex as in fuel-cell mode with hydrogen as fuel. Jeanmonod et al. came to the conclusion, that even concentrations of SO2 as low as 0.5 ppm caused irreversible degradation in Ni/YSZ electrodes in co-electrolysis mode.5 This contribution will report about investigations performed on the degradation caused by sulfur dioxide and silicon species in sub-ppm concentrations in SOCs with Ni/YSZ and Ni/GDC fuel electrodes operated in co-electrolysis mode, using stacks in the Jülich F10 and F20 design. These targeted their impact, potential recovery, possible damage mechanisms and safe thresholds of sulfur dioxide in carbon dioxide. For this the authors performed long-term stationary operation, monitoring of poisoning experiments by electrochemical impedance spectrocopy and post-test analysis of cells, including SEM/EDX and chemical trace analyses. Acknowledgement The authors would like to thank their colleagues at Forschungszentrum Jülich GmbH for their great support and the Helmholtz Society as well as the the German Federal Ministry of Education and Research for financing these activities as part of the Kopernikus P2X-2 project (03SFK2Z0-2). References (1) Peters, R.; Wegener, N.; Samsun, R. C.; Schorn, F.; Riese, J.; Grünewald, M.; Stolten, D. A Techno-Economic Assessment of Fischer–Tropsch Fuels Based on Syngas from Co-Electrolysis. Processes 2022, 10 (4), 699. https://doi.org/10.3390/pr10040699.(2) Schäfer, D.; Queda, L.; Nischwitz, V.; Fang, Q.; Blum, L. Origin of Steam Contaminants and Degradation of Solid-Oxide Electrolysis Stacks. Processes 2022, 10 (3), 598. https://doi.org/10.3390/pr10030598.(3) Skafte, T. L.; Blennow, P.; Hjelm, J.; Graves, C. Carbon Deposition and Sulfur Poisoning during CO2 Electrolysis in Nickel-Based Solid Oxide Cell Electrodes. Journal of Power Sources 2018, 373, 54–60. https://doi.org/10.1016/j.jpowsour.2017.10.097.(4) Liu, W.; Sarofim, A. F.; Flytzani-Stephanopoulos, M. Reduction of Sulfur Dioxide by Carbon Monoxide to Elemental Sulfur over Composite Oxide Catalysts. Applied Catalysis B: Environmental 1994, 4 (2–3), 167–186. https://doi.org/10.1016/0926-3373(94)00019-0.(5) Jeanmonod, G.; Diethelm, S.; Van Herle, J. The Effect of SO 2 on the Ni-YSZ Electrode of a Solid Oxide Electrolyzer Cell Operated in Co-Electrolysis. J. Phys. Energy 2020, 2 (3), 034002. https://doi.org/10.1088/2515-7655/ab8b55.

The investigation of treatment design parameters on carbon integration networks

Carbon Integration methods help identify the appropriate allocation of captured carbon dioxide (CO2) streams into CO2-using sinks, and are especially useful when a number of CO2 sink options are present simultaneously. The method helps identify CO2 allocation scenarios when subjected to an emission target on the CO2 overall network. Many carbon dioxide sink options are costly, and more often than not, require a high purity carbon dioxide source to satisfy the sink demand. Hence, it is imperative to effectively incorporate treatment units in such networks, to obtain high-purity CO2 streams. In fact, it has been previously reported in many studies that the most expensive step in Carbon Capture, Utilization and Sequestration (CCUS) is the treatment system. As a result, this paper focuses on reassessing the performance of carbon integration networks using a more rigorous cost model for the treatment design stage. The effect of utilizing different treatment operating conditions on the overall cost of the treatment stage of CO2 (before allocation) is first captured using a detailed cost model. Subsequently, this information is then fed into a network design problem that involves a CO2 source-sink allocation network problem, and different CO2 net capture targets within the network. For this, an enhanced treatment model that captures all necessary treatment design parameters has been utilized alongside the original model. The original carbon integration formulation has been adopted from previous work. Many of the cost items have been lumped into single parameters in the original formulation, and lack the necessary depth required to carry out the necessary investigations for this work. Hence, the treatment model introduced in this paper is more rigorous, as it accounts for important technical performance constraints on the system to be assessed. Utilizing a more detailed cost model was found to be very helpful in understanding several effects of varying parameters on the overall source-sink allocations, when subjected to different CO2 net emission reduction targets. The cost of the carbon network increases when the solvent temperatures are increased. However, there was a noticeable linear trend at lower temperatures compared to higher temperatures, where the increase became non-linear. Furthermore, it was discovered that for net capture targets of 20% and 25%, no revenue from carbon storage could be generated beyond a solvent temperature of 25 °C. Additionally, the optimal diameter of the treatment column was more responsive to changes in solvent temperature for cases with low net capture targets (below 10%), while its sensitivity decreased for higher capture targets (above 10%).Graphical

Two contrasting years of continuous N[formula omitted]O and CO[formula omitted] fluxes on a shallow-peated drained agricultural boreal peatland

Drained agricultural boreal peatlands comprise a large source of nitrous oxide (N2O) and carbon dioxide (CO2) but a small sink or source of methane (CH4). N2O fluxes have high spatial and temporal variability and are often measured with the chamber technique. Therefore, continuous measurements of N2O fluxes are needed to better understand how N2O emissions are triggered and to reduce the uncertainty of annual N2O budget estimations. Here we present a two-year-long time series of continuous measurements of CO2 and N2O fluxes of a shallow-peated drained agricultural boreal peatland cultivated for grass silage. The fluxes were measured with the area-averaging eddy covariance technique. Several N2O peak events were observed throughout all seasons. The peaks were associated with meteorological or management events, such as soil thawing or freezing, precipitation, fertilization and glyphosate application. The annual N2O budget was 4.74 ±0.47 and 6.08 ±0.49 kg N2O-N ha−1 y−1 in 2020 and 2021, respectively. The annual CO2 budget, comprising the sum of net ecosystem exchange and biomass export, was 3.70 ±0.22 and 5.54 ±0.33 t CO2-C ha−1 y−1 in 2020 and 2021, respectively. The N2O budget during the first, warmer winter was 106% higher than during the second, meteorologically more typical winter, due to the higher frequency of soil freezing–thawing cycles. The average annual N2O budget was 36%–50% lower than the IPCC Emission Factor (EF) while the CO2 budget was in accordance with the IPCC EF. CO2 emissions dominated the total CO2-eq emissions of our site but N2O also had a significant contribution of 12%. Our results also suggest that glyphosate application enhanced N2O emissions in the last quarter of 2021. However, the full rotation should be measured to confirm whether there is a need to re-evaluate the N2O IPCC EF for ‘grassland drained boreal’ land-use class.

Drivers of soil nitrogen availability and carbon exchange processes in a High Arctic wetland

Increased soil nutrient availability, and associated increases in vegetation productivity, could create a negative feedback between Arctic ecosystems and the climate system, thereby reducing the contribution of Arctic ecosystems to future climate change. To predict whether this feedback will develop, it is important to understand the environmental controls over nutrient cycling in High Arctic ecosystems and their impact on carbon cycling processes. Here, we examined the environmental controls over soil nitrogen availability in a High Arctic wet sedge meadow and how abiotic factors and soil nitrogen influenced carbon dioxide exchange processes. The importance of environmental variables was consistent over the 3 years, but the magnitudes of their effect varied depending on climate conditions. Ammonium availability was higher in warmer years and wetter conditions, while drier areas within the wetland had higher nitrate availability. Carbon uptake was driven by soil moisture, active layer depth, and variability between sampling sites and years ( R2 = 0.753), while ecosystem respiration was influenced by nitrogen availability, soil temperature, active layer depth, and sampling year ( R2 = 0.848). Considered together, the future carbon dioxide source or sink potential of high latitude wetlands will largely depend on climate-induced changes in moisture and subsequent impacts on nutrient availability.

Cross efficiency model of network DEA and its application on low carbon efficiency evaluation of multimodal transport

The transportation industry is the main source of carbon dioxide (CO2) emissions, and the development of multimodal transport is conducive to reducing transportation carbon emissions. In order to evaluate the low carbon efficiency of multimodal transport, this article proposes a cross efficiency data envelopment analysis (DEA) method for complex network structures from the perspective of fairness, and takes China's rail-water intermodal transport as an example for research. The proposed method includes two secondary goal models that reduce the unreasonable differences between self-evaluation and peer-evaluation and treat all stages within the network system equally. Then, the improved entropy weight method is used to aggregate the cross efficiency. In addition, a numerical example is given to verify the effectiveness of the proposed method. The results of the case study show that the efficiency of Tangshan Port and Rizhao Port is relatively high, and others should learn from the successful experiences and develop improvement strategies based on their own characteristics. The conclusions can provide reference for transportation enterprise management and policy formulation, and the proposed method can be widely applied to the performance analysis of enterprise network, industrial chain, and supply chain.

Assessing feasible H2–CO2 sources in the US as Feedstocks for Sustainable Aviation Fuel Precursors: Acetic Acid and Ethanol Production via Hydrogenotrophic Pathways

The environmental impact of carbon dioxide emissions is significant, and research is focused on mitigating these emissions and developing eco-friendly technologies in line with green chemistry principles. Waste-to-energy technologies play a crucial role in converting waste into renewable energy and valuable biofuels and bioproducts. This study specifically explores the utilization of waste gas emissions, particularly carbon dioxide, from various sources in the United States for the production of sustainable aviation fuel (SAF) precursors, such as ethanol and acetic acid. The study categorizes and quantifies the volumes of carbon dioxide emissions into three types: non-biogenic, biogenic, and biogenic emissions from ethanol production facilities. Stoichiometric calculations are applied to compare the amounts of carbon dioxide from each category with the available hydrogen production capacity, determining if sufficient hydrogen is present for converting carbon dioxide into SAF precursors. The study reveals two key findings. Firstly, there is a significant reserve of carbon dioxide, approximately 1648 million metric tons per year (MMTy), combining all three categories, which would require a substantial increase of approximately 35–40 times in the existing hydrogen production capacity of 4.988 MMTy. This increased hydrogen production has the potential to yield approximately 1067.82 MMTy of acetic acid and 189.19 MMTy of ethanol annually. Secondly, upon analyzing the quality and application of the three sources of carbon dioxide with the currently available hydrogen production capacity, it is found that biogenic carbon dioxide from ethanol plants is the most suitable choice for immediate production of SAF precursors. This would theoretically result in an annual production of 1.36 MMTy of ethanol and 1.772 MMTy of acetic acid. The other two sources of carbon dioxide can be considered potential reserves for future utilization when additional hydrogen production facilities are established.The study provides a foundation for assessing the aggregation potential required for acetic acid and ethanol production. By optimizing the use of waste gases as raw materials, the study not only enables the production of SAF precursors but also contributes to the passive reduction of greenhouse gas emissions.