CO2 Emissions Research Articles

1-D electrical inversion sensitivity applied to CO2 geological storage monitoring

Discussions on the effects of anthropogenic emissions of greenhouse gas and their consequences on climate change have gained public notoriety in recent decades. The capture of carbon dioxide (CO2) from industrial sources and its subsequent storage in geological reservoirs has the potential to play an important role in reducing the harmful effects of the atmosphere CO2 emissions in the medium and long term. Based on their physical properties for applying geophysical techniques, studying and evaluating the behavior of rocks in the presence of CO2 has shown high relevance. This study deals with monitoring geological reservoirs in the presence of CO2 through the electrical resistivity method to estimate the electrical properties of the rocks involved, such as CO2 saturation and electrical resistivity of the medium. Simulations were performed on a four-layer synthetic model. The results validated the applicability of the electrical method in monitoring CO2 injection and leakage.

Comparative Study of Life-Cycle Environmental and Cost Performance of Aluminium Alloy–Concrete Composite Columns

As is widely known, the construction industry is one of the sectors with a large contribution to global carbon emissions. Despite numerous efforts in the construction industry to develop low-carbon materials, there is a limited number of studies quantifying and presenting the overall environmental impact when these materials are applied in a construction project as structural members. To address this gap, this study focuses on assessing the life-cycle performance of novel structural aluminium alloy–concrete composite columns. In this paper, the environmental impacts and economic aspects of a concrete-filled aluminium alloy tubular (CFAT) column and a concrete-filled double-skin aluminium alloy tubular (CFDSAT) column were assessed using life-cycle assessment (LCA) and life-cycle cost analysis (LCCA) approaches, respectively. The cradle-to-grave system boundary is considered for these analyses to cover the entire life-cycle. A concrete-filled steel tubular (CFST) column is also assessed for reference. All columns are designed to have the same load-carrying capacity and, thus, are compared on a level-playing basis. A comparison is also made of the self-weight of these columns. In particular, the self-weight of the CFST column is reduced by around 17% when the steel tube is replaced by an aluminium alloy tube, and decreased by 47% when the double-skin technique is adopted in CFDSAT columns. The LCA results indicate that the CO2 emission of CFST and CFAT is almost the same, which is 21% less than the CFDSAT columns due to the use of high aluminium in the latter. The LCCA results show that the total life-cycle cost of CFAT and CFDSAT columns is around 29% and 14% lower, respectively, than that of the CFST column. Finally, a sensitivity analysis was carried out to evaluate the effects of data and assumptions on the life-cycle performance of the examined columns.

Deciphering the complex interplay: Heterogeneous, threshold, and mediation effects of trade openness on CO2 emissions in Africa.

Despite having barely anything to do with the issue of CO2 emissions, Africa has been experiencing more severe climate change and its adverse effects than most other regions of the globe. However, the issue of CO2 emissions and its adverse effects has received relatively little attention in the African research arena. To this end, the present research assesses the effect of trade openness on the CO2 emissions utilizing panel data from 46 African countries spanning 2000 through 2022. To account for the possible heterogeneity and nonlinearity, the panel quantile regression and threshold methods were employed. Moreover, this study investigates the key mediating effects of the channel. The empirical findings show that greater trade openness is associated with significantly higher CO2 emission, additionally; it demonstrates that the influence is heterogeneous across different CO2 emission quantiles in African countries. Besides the result from the double threshold model reveals a complex, nonlinear relationship between trade openness and CO2 emissions in Africa. Moreover, the findings divulge that openness to trade indirectly reduces CO2 emissions through the substitution and technology channels whereas it indirectly increases carbon dioxide production via the economic track. Therefore, it is vital to promote the use of renewable energy, effectively leverage the knowledge spillover effects of trade to decrease energy intensity and formulate pertinent policies aimed at curbing carbon emissions and addressing the imminent threat of climate change in Africa. Besides, the nonlinear and heterogeneous effects of trade openness on CO2 emissions suggest that policies and interventions related to the impact of trade openness on CO2 emissions should consider the current level of carbon dioxide emissions.

Natural resource rent, green finance, and CO2 emissions from the industrial sector

This study investigates the effect of natural resource rents and green finance on industrial sustainability in 20 OECD countries from 2010 to 2020, using the CCEMG-ARDL approach. Findings reveal that a 1% increase in green finance reduces CO2 emissions by 0.43% in the short term and 0.27% in the long term, highlighting its role in supporting environmentally friendly investments. In contrast, a 1% rise in fossil fuel rents increases CO2 emissions by 0.29% short-term and 0.05% long-term, showing the pollutive impact of fossil fuel profits. Additionally, a 1% increase in electricity usage raises CO2 emissions by 0.41% short-term and 0.16% long-term, stressing the need for cleaner energy. Industry-specific patents show limited alignment with sustainability goals. Policy measures should target resource rent management, boost green finance, and encourage sustainable practices to promote industrial greening.

Net‐Zero Transition Pathways in Belt and Road Economies: Insights From Threshold Effects and Heterogeneous Analysis

ABSTRACTGiven the pressing need for economies to mitigate climate change and champion carbon neutrality, this study investigates the threshold effects of financial development and foreign direct investment (FDI) on carbon dioxide (CO₂) emissions in Sub‐Saharan Africa (SSA) within the Belt and Road Initiative (BRI) bloc, taking into account the moderating role of the regulatory environment. Drawing on the environmental Kuznets curve and the pollution haven hypothesis, the study utilizes the dynamic generalized method of moments (GMM) modeling, proposed by Arellano and Bover, to analyze panel data from 37 SSA countries spanning 1990–2022. The findings reveal that financial development in the banking, financial, and private sectors, along with FDI outflows, is associated with a reduction in CO₂ emissions. Conversely, FDI inflows are linked to increased CO₂ emissions. A curvilinear relationship is observed, where initial increases in financial development and FDI correlate with higher emissions, which decline beyond a certain threshold. Stronger regulations enhance the positive impact of financial development on reducing CO₂ emissions. Finally, the findings show a significant heterogeneous effect across the SSA regional blocs. These findings underscore the critical need for implementing stringent environmental regulations and promoting sustainable financial practices to mitigate negative environmental impact. This research provides both theoretical and practical insights into fostering a carbon neutrality agenda and advancing Sustainable Development Goal 13.

Investigations on animal fat biodiesel selected blend by varying the fuel injection pressures and timings in the four-stroke single cylinder compression ignition engine

In the earlier investigations on the animal fat biodiesel, the authors have found that blend 20 was suitable to run the engine. In the CI engines, operating input parameters, FIPs and FITs, are the significant parameters to improve the engine performance and emission characteristics. Biodiesel was prepared by the transesterification process and blended with 20% diesel fuel to get AFB20 blend and to carried out the experiments by varying the FIPs by 180, 200, 220 and 240 bars and FITs by 19°, 21°, 23°, 25° and 27° bTDCs. The experiments were investigated in the single-cylinder 4S CI engine. In the evaluation, it was found that the FIP of 200 bar and 180 bar consumes 0.96% lower BSFC compared to 240 & 220 bars and exhibits a higher BTE of 2.6%. 1.62% lower EGT was found in 240 bar compared to 180 bar. 0.86% lower UBHC and 24.67% lower smoke emissions were observed in 200 and 240 bars. Lower BSFC was found in the 23° IT and higher BTE was found in 19° IT. Lower EGT and UBHC emissions were found in 19° IT. Lower EGT and CO emissions were found in 19° CA and higher CO emission was found in 23° IT at full load.

A sustainable and expedited ‘One‐Stop’ prostate cancer diagnostic pathway to reduce environmental impact and enhance accessibility

AbstractObjectiveTo assess the carbon footprint, accessibility, and diagnostic performance of an expedited ‘One‐Stop’ prostate cancer (PCa) diagnostic pathway.Materials and methodsA total of 1083 consecutive patients undergoing magnetic resonance imaging (MRI) followed by transrectal ultrasound fusion‐guided prostate biopsy (PBx) were identified from a prospective database. The patients were divided according to the diagnostic pathway: One‐Stop, with MRI and same‐day PBx (3 hours apart), or Standard, with MRI followed by a second visit for PBx. Socioeconomic status was evaluated by the Distressed Communities Index (DCI) and the carbon footprint by the United States (U.S.) Environmental Protection Agency Greenhouse Gases Equivalencies Calculator.ResultsOverall, 260 patients underwent the One‐Stop and 823 the Standard pathway. The One‐Stop patients lived farther from the hospital (163 vs. 23 km; p < 0.001), had lower socioeconomic status with DCI scores of 49 versus 30 (p < 0.001), and were more likely to be Latinos (21% vs. 13%, p < 0.001) compared to the Standard patients, respectively. The One‐Stop saved 69 575 km in round trips, over 16 tons of travel‐related CO2 emissions, and $8214 U.S. dollars. For patients with Prostate Imaging Reporting & Data System (PIRADS) 3–5, the clinically significant PCa detection (53% vs. 50%, p = 0.55) was similar for the One‐Stop and Standard pathways, respectively.ConclusionsThe One‐Stop PCa diagnostic pathway reduces carbon footprint, distance travelled, and patient‐level cost while maintaining clinical outcomes comparable to the Standard pathway. It facilitates access to tertiary‐level care for minorities and underserved populations.

Ocean alkalinity enhancement approaches and the predictability of runaway precipitation processes: results of an experimental study to determine critical alkalinity ranges for safe and sustainable application scenarios

Abstract. To ensure the safe and efficient application of ocean alkalinity enhancement (OAE), it is crucial to investigate its impacts on the carbonate system. While modeling studies reported a sequestration potential of 3–30 Gt carbon dioxide (CO2) per year (Oschlies et al., 2023), there has been a lack of empirical data to support the applicability of this technology in natural environments. Recent studies have described the effect of runaway carbonate precipitation in the context of OAE, showing that calcium carbonate (CaCO3) formation was triggered if certain Ωaragonite saturation thresholds were exceeded. This effect could potentially lead to a net loss of the initially added alkalinity, counteracting the whole concept of OAE. The related precipitation can adversely affect the carbon storage capacity and may in some cases result in CO2 emissions. Experiments at the Espeland marine biological station (Bergen, Norway) were conducted to systematically study the chemical consequences of OAE deployment. The experiments lasted for 20–25 d to monitor the temporal development of carbonate chemistry parameters after alkalinity addition and the subsequent triggered carbonate precipitation process. Identified uniform patterns before and during the triggered runaway process can be described by empirical functional relationships. For approaches equilibrated to the CO2 concentration of the atmosphere, total alkalinity (TA) levels of up to 6500 µmol kg−1 remained stable without loss of total alkalinity (TA) for up to 20 d. Higher implemented TA levels, up to 11 200 µmol kg−1, triggered runaway carbonate formation. Once triggered, the loss of alkalinity continued until the Ωaragonite values leveled out at 5.8–6.0, still resulting in a net gain of 3600–4850 µmol kg−1 in TA. The non-CO2-equilibrated approaches, however, only remained stable for TA additions of up to 1000 µmol kg−1. The systematic behavior of treatments exceeding this level allows us to predict the duration of transient stability and the quantity of TA loss after this period. Once triggered, the TA loss continued in the non-CO2-equilibrated approaches until Ωaragonite values of 2.5–5.0 were reached, in this case resulting in a net loss of TA. To prevent a net loss of TA, treated water must be diluted below the time-dependent critical levels of TA and Ωaragonite within the identified transient stability duration. Identified stability and loss patterns of added TA depend on local environmental conditions impacting the carbonate system, such as salinity, temperature, biological activity, and particle abundance. Incorporating such stability and loss patterns into ocean biogeochemical models, which are capable of resolving dilution processes of treated and untreated water parcels, would, from a geochemical perspective, facilitate the prediction of safe local application levels of OAE. This approach would also allow an accurate determination of the fate of added alkalinity and a more realistic carbon storage potential estimation compared to the assessments that neglect carbonate system responses to OAE.

Retraction Note: Long-run equilibrium relationship between energy consumption and CO2 emissions: a dynamic heterogeneous analysis on North Africa.

Retraction Note: Long-run equilibrium relationship between energy consumption and CO2 emissions: a dynamic heterogeneous analysis on North Africa.

Emissions and Flame Stability Assessment of Hydrogen Addition and Air Dilution in a Micro Gas Turbine Combustor Using 0D/1D Modeling by Chemical Reactor Network

Abstract Hydrogen emerges as a promising fuel for clean and sustain- able electricity production when utilized in micro gas turbines (mGTs). However, some challenges linked to hydrogen usage must be overcome as its high reactivity can lead to increased NOx emissions and flame instabilities. Literature suggests that combustion air humidification and/or exhaust gas recirculation (EGR) may be methods to reduce this reactivity. However, these measures are limited due to the small operating range of the mGT combustor. In this context, a 20 kWth mGT combustor is investigated un- der various inlet conditions to assess the effect of EGR towards increased flame stability and emission control when operating under hydrogen-enriched methane firing, using a Chemical Re- action Network (CRN) model. The CRN modeling is a fast and low computational complexity tool to model combustion perfor- mance and emissions by representing complex reactive flow fields through idealized reactor models, leading to reduced computa- tional costs. This study examines partial load conditions, fuel compositions, and the effect of combustion air dilution through EGR. The CRN model of the combustion process is designed based on combustion zones extracted from the main flow fields with similar thermo-chemical states from CFD, while emission predictions are experimentally validated for different operating points. Predicted NOx and CO emissions by the proposed CRN model show an acceptable agreement with the experimental data at high power loads. However, its accuracy diminishes for loads below 70% due to the variability in model tuning parameters across different loads, whereas the

Effect of Methane on Combustion of Glycerol and Methanol Blends Using a Novel Swirl Burst Injector in a Model Dual-Fuel Gas Turbine Combustor

Glycerol, a byproduct of biodiesel, has moderate energy but high viscosity, making clean combustion challenging. Quickly evaporating fine fuel sprays mix well with air and burn cleanly and efficiently. Unlike conventional air-blast atomizers discharging a jet core/film, a newly developed swirl burst (SB) injector generates fine sprays at the injector’s immediate exit, even for high-viscosity fuels, without preheating, using a unique two-phase atomization mechanism. It thus resulted in ultra-clean combustion for glycerol/methanol (G/M) blends, with complete combustion for G/M of 50/50 ratios by heat release rate (HRR). Lower combustion efficiencies were observed for G/M 60/40 and 70/30, representing crude glycerol. Hence, this study investigates the effect of premixed methane amount from 0–3 kW, and the effect of atomizing gas to liquid mass ratio (ALR) on the dual-fuel combustion efficiency of G/M 60/40-methane in a 7-kW lab-scale swirl-stabilized gas turbine combustor to facilitate crude glycerol use. Results show that more methane and increased ALR cause varying flame lift-off height, length, and gas product temperature. Regardless, mainly lean-premixed combustion, near-zero CO and NOx emissions (≤2 ppm), and ~100% combustion efficiency are enabled for all the cases by SB atomization with the assistance of a small amount of methane.

Techno-Economic Comparative Assessment of High Temperature Heat Pump Architectures for Industrial Pumped Thermal Energy Storage

Abstract The industrial sector is a key global source of wealth, but it is also recognized as a major challenge toward worldwide decarbonization. Today the industrial sector requires more than 22 % of the global energy demand as thermal energy and produces for this about 40 % of the total CO2 emissions. Solutions to efficiently decarbonize the industrial sector are deemed. This work presents a comparative techno-economic performance assessment of a high temperature heat pump integration within a molten salts based power to heat system for industrial heat flexible generation. The main system performance is reported in terms of required working conditions and temperature for the heat pump and thermal demand size as well as reduction of the attainable levelized cost of heat (LCoH) against non-flexible electric boiler based systems. The impact of different industrial load profiles, electricity prices, heat pump capital cost and heat pump real to Carnot efficiency ratio are also presented. The results highlight that the proposed system can be cost-competitive, particularly for thermal demand around 10 MW and waste heat temperatures above 80°C. Under these conditions LCoH reductions higher than 15 %, with respect to the considered non-flexible electric boiler alternative, are attainable. These LCoH reductions are primarily driven by savings in electrical consumption as high as 30 %. This study sets the ground for further power-to-heat techno-economic investigations addressing different industrial sectors and identifies main system and components design strategies, integrations, and targets.

Support Carbon Neutral Goal with a High-resolution Carbon Monitoring System in Beijing

Abstract China has committed to peak its carbon emissions before 2030 and achieve carbon neutrality before 2060, known as the Dual Carbon Goals (DCG). To support the DCG, monitoring and assessment of progresses in emissions reduction have become a central research focus. Here we describe the Beijing-Tianjin-Hebei (JJJ) Carbon Monitoring System, established over the last six years through a collaborative effort of 16 research institutions and universities. The monitoring capability includes ground-based high-precision reference stations, a dense network of medium-accuracy low-cost sensors, carbon satellites, vertical profile samplers, and mobile platforms. Observations using the network have shown CO2 variations from diurnal, synoptic to seasonal-interannual timescales, as well as dramatic on-road changes during the COVID-19 lockdown. High-resolution modeling and data assimilation at km-scale reveal major deficiencies in global carbon emissions datasets at regional/city scale. The inversion found the total fossil fuel CO2 emissions of the City of Beijing to be 117 megatonne (Mt), but much lower than the national-data-based inventories (152 MtCO2). The results have been used in emissions assessment by national and local environmental protection agencies. Similar systems are now being developed in other Chinese cities.

A Study of Heat Recovery and Hydrogen Generation Systems for Methanol Engines

Biofuels are the most essential types of alternative fuels, which currently have significant potential to reduce CO2 emissions compared to fossil fuels. Methanol is a more efficient fuel than petrol due to its physicochemical properties, such as a higher latent heat of vaporization, research octane number, and heat of combustion of the fuel–air mixture. Also, biomethanol is cheaper than traditional petrol and diesel fuel for agricultural countries. The authors have proposed a new approach to improve the characteristics and efficiency of methanol diesel engines by using biomethanol mixed with hydrogen instead of pure biomethanol. Using a hydrogen–biomethanol mixture in modern engines is an effective method because hydrogen is a carbon-free, low-ignition, highest-flame-rate, high-octane fuel. A small quantity of hydrogen added to biomethanol and its combustion in an engine with a heat exchanger increases the combustion temperature and heat release, increases engine power, and reduces fuel consumption. This article presents experimental results of methanol combustion and a hydrogen-in-methanol mixture if hydrogen was retained due to the utilization of the heat of the exhaust gases. The tests were carried on a single-cylinder experimental engine with an injection of liquid methanol and gaseous hydrogen mixtures. The experiments showed that green hydrogen generated onboard the car due to the utilization of heat significantly reduced fuel costs of engines of vehicles and technological installations. It was established a hydrogen gaseous mixture addition of up to 5% by mass to methanol requires a corresponding change in the coefficient of excess air to λ = 1.25. Also, using an additional hydrogen mixture requires adjustment at the ignition moment in the direction of its decrease by 4–5 degrees of the engine crankshaft. Hydrogen gas mixture addition reduced methanol consumption, reaching a maximum reduction of 24%. The maximum increase in power was 30.5% based on experimental data. The reduction in the specified fuel consumption, obtained after experimental tests of the methanol research engine on the stand, can be implemented on the vehicle engines and technological installations equipped with an onboard heat recovery system. Such a system, due to the utilization of heat and the supply of additional hydrogen, can be implemented for engines that work on any alternative or traditional fuels.

CH4 and CO emission estimates for megacities: deriving enhancement ratios of CO2, CH4, and CO from GOSAT-2 observations

Abstract Enhancement ratios among trace gases co-emitted by combustion of fossil fuels vary with emission sources and their combustion efficiency. We used column-averaged dry-air mole fractions of carbon dioxide (XCO2), methane (XCH4), and carbon monoxide (XCO) from the Greenhouse gases Observing SATellite-2 (GOSAT-2), a unique satellite that observes them simultaneously with the same field of view, to derive the enhancement ratios (ΔXCO/ΔXCO2, ΔXCO/ΔXCH4, and ΔXCH4/ΔXCO2) for the 40 most populous cities in the world. These enhancement ratios were used to evaluate the Emissions Database for Global Atmospheric Research (EDGAR). For cities where the difference in the 2015 EDGAR CO emissions between the latest versions (v6.1 and v5.0) was 30% or less, the GOSAT-2 ΔXCO/ΔXCO2 ratios and EDGAR (v6.1/v7.0) CO/CO2 emission ratios were in good agreement (correlation coefficient of 0.65). For ~70% of the cities where the difference of CO emissions exceeded 30%, the EDGAR CO/CO2 emission ratios using v6.1 CO emissions were in better agreement with the GOSAT-2 ΔXCO/ΔXCO2 ratios than those using v5.0 CO emissions, indicating that v6.1 CO emissions were improved over v5.0 emissions. However, for the remaining cities, the version upgrade may have reduced the CO emissions too much. The CH4 and CO emissions for each city were then estimated from the ΔXCH4/ΔXCO2 and ΔXCO/ΔXCO2 ratios, respectively, by reference to the CO2 emissions from the Open-data Inventory for Anthropogenic CO2 (ODIAC) or EDGAR. Compared to our estimates using the ODIAC (EDGAR) CO2 emissions, the EDGAR v7.0 CH4 and v6.1 CO emissions were underestimated for 74% (57%) and 76% (53%), respectively, of all cities where results were available. For several cities where emissions were estimated using in situ observations and ground-based remote sensing observations, our results were in reasonable agreement with these results. The implication is that satellite-derived enhancement ratios can provide informative constraints on anthropogenic emissions in megacities.

Examining the Causal and Heterogeneous Influence of Three-Dimensional Urban Forms on CO2 Emissions in 285 Chinese Cities

Despite the efforts to examine the influence of urban forms on CO2 emissions, most studies have mainly measured urban forms from a two-dimensional perspective, with relatively little attention given to three-dimensional urban forms and their causal relationships. Utilizing the built-up area dataset from the Global Human Settlement Layer (GHSL) project and the carbon emission dataset from the China City Greenhouse Gas Working Group (CCG), we examine a causal and heterogeneous effect of three-dimensional urban forms on CO2 emissions—specifically urban height, density, and intensity—in 285 Chinese cities. The empirical results reveal a robust and positive causal effect of 3D urban forms on carbon emissions. Even when incorporating the spatial spillover effect, the positive effect of 3D urban forms remains. Moreover, GDP per capita and total population have a greater impact on urban CO2 emissions. Additionally, we find that the influence of 3D urban forms on CO2 emissions is U-shaped, with total population serving as a moderating factor in this effect. Importantly, there is significant geographic and sectoral heterogeneity in the influence of 3D urban forms on CO2 emissions. Specifically, the influence of 3D urban forms is greater in eastern cities than in non-eastern cities. Furthermore, 3D urban forms primarily influence household carbon emissions rather than industrial and transportation carbon emissions. Therefore, in response to the growing challenges of global climate change and environmental issues, urban governments should adopt various strategies to develop more rational three-dimensional urban forms to reduce CO2 emissions.

Predicting China’s Energy Consumption and CO2 Emissions by Employing a Novel Grey Model

The accurate prediction of China’s energy consumption and CO2 emissions is important for the formulation of energy and environmental policies and achieving carbon neutrality. This paper proposes a new weighted error evaluation criterion that emphasizes the importance of new data, thereby enabling more accurate capture of the variation characteristics of new data and reflecting the principle of new information priority. By optimizing the development coefficient, grey action, and parameters in the time response formula of the traditional GM(1,1), a novel optimized model, OGMW(1,1), is constructed. The accuracy of the new model is verified by three cases from the literature. The future trends of primary energy, oil, and coal consumption and CO2 emissions in China are predicted over the next five years. The conclusions are as follows: First, the new weighted error evaluation criteria are effective and reasonable and can indicate whether a grey model can reliably use the most recent information for modeling. Second, based on the new error evaluation criteria, the development coefficient, ash action, and parameter C in the time response function can be optimized. The results show that the optimization method is reasonable. Third, compared with the traditional models GM, GMO, and ARIMA, the OGMW(1,1) provides better simulation and prediction accuracy, and new information can be prioritized more effectively. Fourth, the forecasting results indicate that China will increase its consumption of primary energy, oil, and coal, as well as its CO2 emissions. Notably, the growth rates of primary energy and oil consumption are high at approximately 22.7% and 25%, coal consumption will increase slightly, and CO2 emissions will increase by approximately 11%.

Coal Phase-Out and Carbon Tax Analysis with Long-Term Planning Models: A Case Study for the Chilean Electric Power System

Large CO2 emissions constitute a significant problem today due to their effect on climate change, and the need to design appropriate energy policies to mitigate their consequences and reduce emissions requires a detailed analysis of one of the main sources of such emissions: the electricity system. Thus, this paper presents a study on the effects of energy policies on decarbonization by comparing the detailed phase-out of coal-fired power plants across a range of cases with the implementation of a carbon tax to meet Nationally Determined Contributions (NDCs). The case study focuses on the Chilean electricity system, using a long-term generation and transmission expansion planning model (GTEP) that incorporates a wide range of generation technologies. The study examines the long-term effects of these policies, including costs, investments, and CO2 emissions, as well as their impact on consumer prices reflected in the marginal costs of the system. The transmission system modeling covers various regions of Chile and significant projections for renewable energy sources. It evaluates three economic scenarios based on generation technology costs, fuel prices, and electricity demand under four different closure schemes and fourteen different carbon tax levels. The results indicate that implementing a carbon tax can be more cost-effective for the system than the implementation of a phase-out schedule for coal plants, taking the form of reduced CO2 emission and overall system costs, with an optimal carbon tax value of 37 USD/tCO2. Additionally, the study reveals significant effects on consumer prices, showing that a carbon tax as an energy policy leads to lower prices compared to a phase-out scheme.

The Effect of the Use of a Novel Urease Inhibitor Coated Urea on the Greenhouse Gas Emissions and Ammonia Volatilization Losses from a Maize Field

Nitrogen fertilizers are essential for enhancing agricultural productivity but are also major contributors to greenhouse gas (GHG) emissions and ammonia volatilization, which affect environmental sustainability. This study evaluated the effect of cashew nut shell liquid (CNSL)-coated urea on GHG emissions and ammonia losses from maize fields in the Indo-Gangetic Plains, known for excessive nitrogen fertilizer usage. A randomized block design was employed with four treatments: control (no nitrogen), prilled urea, neem-coated urea (NCU), and CNSL-coated urea (CCU). Gas samples were collected using the closed chamber method, and emissions of CO₂ and N₂O were analyzed via gas chromatography. Ammonia volatilization was measured using the forced air draft method. Results showed that the CCU treatment significantly reduced ammonia volatilization compared to prilled urea (15.84% reduction), with reductions of 9% to those observed with NCU. Moreover, CCU-treated plots exhibited reduced cumulative GHG and lower global warming potential (GWP) without compromising maize yields. Cumulative GHG emissions varied among the treatments in the order urea> CCU> NCU> Control. CCU treated plots exhibited a net GWP decrease of 8.59% compared to urea and an increase of 4.13% compared to NCU. These findings suggest that CNSL-coated urea can serve as an eco-friendly alternative to conventional urea, potentially mitigating environmental impacts associated with nitrogen fertilization. Further studies are recommended to assess the long-term efficacy of CNSL in various soil types and climatic conditions.

Evaluating the environmental benefits of autonomous vehicles in urban intersections: a microscopic simulation approach

This research delves into the environmental and energy implications of incorporating autonomous vehicles (AVs) into urban traffic systems, mainly focusing on emissions and fuel efficiency. The study employed PTV VISSIM simulation software to model a four-leg signalized intersection in Balgat, Ankara, under varying levels of AV integration and driving behaviors. A total of 21 scenarios were simulated, assessing the impact of cautious, normal, aggressive, and platooning AV behaviors on emissions of CO, NOx, and VOCs, as well as fuel consumption, across different traffic signal cycle durations. The results indicate that shorter signal cycle times consistently significantly reduce emissions and fuel consumption, irrespective of AV driving behavior. The most notable improvements were observed in platooning scenarios, attributed to their optimized traffic flow. In contrast, longer cycle times increased emissions and fuel consumption, especially with human-driven and cautious AVs, due to more frequent idling and stop-and-go traffic patterns. This study highlights the importance of refining AV driving algorithms and optimizing signal control systems to reduce environmental impacts and improve fuel efficiency in urban settings, providing crucial insights for advancing sustainable urban mobility and traffic management strategies.