Mitigate CO2 Emissions Research Articles

Greenhouse gas fluxes of microbial‐induced calcite precipitation at varying urea‐to‐calcium concentrations

AbstractMicrobial‐induced calcite precipitation (MICP) is regarded as environmentally friendly, partly due to the storage of carbon as carbonates. Although CO2 emissions during MICP have been reported, quantification of its environmental impact regarding total greenhouse gas fluxes has not yet been thoroughly investigated. In particular, N2O fluxes could occur in addition to CO2 since MICP involves the microbially mediated nitrogen cycle. This study investigated the greenhouse gas fluxes during biostimulation of MICP in quartz sand in incubation experiments. Soil samples were treated with MICP cementation solution containing calcium concentrations of 0, 20, 100 and 200 mM at a fixed urea concentration of 100 mM to offer a range of carbonation potential and/or mitigation of CO2 emissions. Greenhouse gas (CO2, CH4 and N2O) measurements were determined by gas chromatography during incubations. Soil total inorganic carbon and the isotopic composition of precipitated and emitted CO2 were determined by isotope ratio mass spectrometry. CO2 emissions (0.52 to 4.08 μg of CO2–C h−1 g−1 soil) resulted from MICP, while N2O and CH4 fluxes were not detected. Increasing Ca2+ with respect to urea resulted in lower CO2 emissions, lower solution pH, similar carbonate precipitation and urea hydrolysis inhibition. The highest urea‐to‐calcium ratio (1:0.2) emitted roughly two times the amount of CO2 (112 μg of CO2–C g−1 soil) compared to the 1:1 and 1:2 ratios (47 to 58 μg of CO2–C g−1 soil) and five to six times more than samples that did not receive Ca2+ (1:0) (~18 μg of CO2–C g−1 soil). Precipitated CaCO3–C was tenfold higher than cumulative emitted CO2–C, and isotopic analysis indicated both emitted and precipitated carbon were of urea origin. Both emitted and precipitated carbon accounted for a very low percentage of total carbon applied in the system (<0.35 and <4.5%, respectively), presumably due to limited urea hydrolysis which was negatively affected by increasing the Ca2+ concentration.

Higher education’s impact on CO2 mitigation: MENA insights with consideration for unemployment, economic growth, and globalization

This study investigates the intricate interplay between higher education and environmental pollution in the MENA region from 2000 to 2018. Employing a comprehensive analytical approach, including cross-dependency tests alongside panel unit root tests, Kao cointegration tests, fixed effect GLS, DOLS (dynamic ordinary least squares), FMOLS (fully modified ordinary least squares) estimations, and Granger causality tests, the research focuses on three critical control variables—Unemployment, gross domestic product, and the globalization index. GLS analysis reveals a positive correlation between higher education, globalization, GDP per capita, and CO2 emissions in the MENA region. However, delving deeper using DOLS and FMOLS, a nuanced perspective emerges, indicating the role of higher education and globalization in mitigating CO2 emissions in the long run, challenging the Kuznets curve hypothesis. Additionally, causality tests highlight the significant influence of higher education and globalization on CO2 emissions. These findings address a critical gap in the understanding of environmental dynamics in the MENA region and offer valuable insights for policymakers and governments, informing targeted interventions and policies for sustainable development and reduced CO2 emissions.

A Sensor-Based Application for Eco-Driving Management in Short-Term Car Rentals

How to reduce fuel consumption to mitigate CO2 emissions to the atmosphere and improve road safety is one of the priorities to be addressed in the field of transport in the European Union. Considering the trend towards more frequent car rentals, it seems important to encourage drivers to change their driving style to a more ecological and economic one. This can be achieved by a system (built of a sensor located in the car, analytical software in the cloud and a mobile application for displaying results) that analyzes driving style and tells the driver how to drive better. Solutions such as the car bus PCB, GSM/GPS modem and 3D sensors were used in the development of the sensor. The validation of the sensor and the development of the analytical system are based on tests carried out in road conditions and in a closed area. Graphical methods (box-plot charts), correlation analysis and testing statistical hypotheses using the Mann–Whitney method were used in the analysis of the test results. The developed sensor and the analytical system allow for identifying the driving style of drivers. This system, through the use of a sensor that allows for downloading data not only from the car’s CAN bus but also the forces acting on the vehicle, permits the checking of 14 driving parameters used to interpret the driver’s driving style.

Multiple thermoelectric cogeneration system in an industrial thermal peeling press machine – Thermal modeling, case studies, and parametric analysis

Cogeneration systems, exploiting waste heat sources, have emerged as crucial solutions in decreasing energy consumption and mitigating CO2 emissions across diverse industrial domains. This study delves into the innovative integration of multiple waste heat recovery (MWHR) mechanisms with thermoelectric generators (TEGs) within industrial contexts, with a specific emphasis on harnessing exhaust gas heat. Through meticulous investigation, six distinct configurations of TEG placement covering three unique systems were examined to expose their influence on overall system efficacy. Findings clarify a deep correlation between TEG positioning and system performance, with TEGs strategically positioned in close to heat sources, particularly along the inner walls of exhaust pipes, demonstrating the most auspicious outcomes in terms of power generation. Furthermore, the study reveals notable metrics, including a maximum power efficiency of 0.11 W per TEG and a water heat flow rate peaking at 5114 W. However, a comprehensive analysis underscores the imperative for interpreting the primary mechanisms governing TEG placement's impact on system performance, alongside defining the practical implications of the observed power efficiency and water heat flow rate. These empirical insights underscore the transformative potential of WHR-TEG interactions in optimizing energy utilization within industrial ecosystems, highlighting the request for further research actions aimed at implementation strategies and sustainability benchmarks.

The copper size effect of CuZn/CeO2 catalyst in CO2 hydrogenation to methanol

The escalating emission of CO2 has caused a significant environmental impact. Hydrogenation of CO2 to methanol stands as the primary objective in the liquid sunlight vision, aiming to mitigate CO2 emissions. CuZn-based transition metal catalysts, known for their cost-effectiveness, demonstrate commendable catalytic performance at moderate temperatures and pressures, showcasing considerable potential in industrial applications. Consequently, a series of catalysts, composed of CuZn-based species supported on CeO2 with strategically introduced appropriate oxygen vacancies, were meticulously prepared. It worth to noting that the size of Cu was precisely tuned, along with the enhanced ability to the adsorption and activation of CO2 and H2. As a result, the optimal CuZn/CeO2 catalyst exhibits high methanol formation rate, recording at 433.4 gMeOH kgcat−1 h−1 with selectivity of 68.5% at 260 °C and 3 MPa. Simultaneously, the reaction path and the evolution of intermediates in CO2 hydrogenation was thoroughly delineated.

Efficacy of CO2 emission reduction strategies by countries pursuing energy efficiency, nuclear power, and renewable electricity

The discussion on CO2 mitigation strategies is increasing, and investors are interested in disclosing electricity generation pathways that effectively alleviate CO2 emissions. As such, this research proposes hierarchical analyses using stepwise regression and pairwise correlation for 133 countries over 31 years to explain how they use their energy sources, including efficiency, nuclear, and renewable electricity pathways, to mitigate CO2 emissions. Firstly, the results discover that renewable electricity effectively mitigates CO2 emissions, further supported by the incremental change in the R-squared value. Secondly, the results do not support the idea that nuclear power mitigates CO2. In contrast, it is noted that the efficacy of nuclear power on CO2 emission mitigation is effective through the moderation of GDP. This relationship demonstrates that the connection between CO2 and nuclear power is conducive to environmental quality in countries with increasing economic growth. Third, the negative coefficients of energy efficiency across the tested models indicate that the countries' energy efficiency is effective in CO2 emissions reduction. Finally, the results discovered that nuclear and renewable electricity pathways tend to crowd out each other, where this phenomenon is not valid in the cases of nuclear power-energy efficiency and renewable electricity-energy efficiency, where they support each other.

The integration of solar-hydrogen hybrid renewable energy systems in oil and gas industries for energy efficiency: Optimal sizing using Fick's Law optimisation Algorithm

The global demand for sustainable energy solutions in the oil and gas industry has stimulated interest in the integration of renewable energy sources. This paper investigates the techno-economic and environmental aspects of incorporating a solar-hydrogen-based hybrid renewable energy system (SHRES) into oil and gas processing facilities.The proposed SHRES, comprising Solar PV modules, hydrogen production and storage systems, and a gas turbine generator (PV-FC-EL-Tank-GT), aims to enhance energy efficiency and reduce the carbon footprint of energy-intensive operations. The study utilises a multidisciplinary approach, encompassing engineering, economics, and environmental analysis. The techno-economic evaluation employs detailed modelling and optimisation using Fick's Law Algorithm, ensuring efficient energy production and cost-effectiveness. Ecological assessments quantify potential reductions in greenhouse gas emissions and other environmental impacts.The technical and economic evaluation identifies the electrolyser system as the most significant cost contributor (57%). The optimised system balances energy sources with 45% from PV modules, 35% from fuel cells, and 20% from gas turbines, showcasing substantial reliance on renewable energy while maintaining required power generation.Addressing the urgent need for sustainable energy solutions in the oil and gas industry, the study highlights the potential of SHRES integration. By employing Fick's Law Algorithm, alongside with 80 % of renewable energy integration, the research optimises system components to optimise the annualised cost to be $57,539.85, decrease to zero the Loss of Power Supply Probability (LPSP), and mitigate CO2 emissions to a lowest value of 0.147 gCO2eq/kWh (by 80 %). The electrolyser system's pivotal role and the distribution of power generation sources are emphasised.This study presents a novel approach to integrating solar-hydrogen systems into oil and gas processing facilities, aiming for sustainability. The findings underscore the significance of the electrolyser system and the distribution of power generation sources in optimising the SHRES. Recommendations for renewable energy integration and potential reductions in CO2 emissions and costs are discussed, providing valuable insights for future energy policies.

The effect of H2 and NH3 on the pyrolysis of coal model compounds based on reactive molecular dynamics simulation

The co-combustion of coal and ammonia (NH3) has been receiving considerable attention due to its potential for mitigating CO2 emissions. Consequently, comprehending the pyrolysis mechanism of coal under the NH3 atmosphere is of paramount significance. Using pyrrole and pyridine, which are crucial model compounds of coal, the pyrolysis mechanisms within N2/H2/NH3 is systematacially investigated with the help of chemical reaction kinetics simulations (ReaxFF MD). The results revealed that pyrrole performs inferior structural stability compared to pyridine, resulting in accelerated and shorter pyrolysis, alongside a lower activation energy for the reaction. As a result, the pyrolysis process of pyrrole is more prone to C-C and C-N bond cleavage, ultimately producing more HCN. Moreover, this investigation revealed that both H2 and NH3 atmospheres promote the pyrolysis of pyrrole and pyridine, with the NH3 atmosphere having a more pronounced influence. The presence of an NH3/H2 atmosphere increased the production of HCN, lowered the activation energy required for the pyrolysis of pyrrole and pyridine, and aided in the cleavage of C-C and C-N bonds. Additionally, this study demonstrated the reaction network of pyrrole and pyridine in N2/H2/NH3 atmospheres, focusing on the observation that NH2 radicals, during the initial phases of the reaction, stimulate the production of low-carbon fragments and assist the fracture process of the model compounds. Furthermore, this study presents the reaction network of pyrrole and pyridine in N2/H2/NH3 atmospheres, with a particular focus on the NH3 atmosphere. The existence of NH3 in the atmosphere facilitates the formation of low-carbon fragments during the cleavage phase of the model compounds. This leads to the production of low-carbon intermediates and an increase in the generation of HCN during the subsequent condensation stage. These findings highlight the significant impact of the ammonia atmosphere on the pyrolysis of the model compounds. The outcomes of this study elucidate the fundamental principles of nitrogen-containing compound pyrolysis at the mechanistic level, providing critical insights for subsequent experimental and computational research.

High-Performance Reversible Solid Oxide Cells for Powering Electric Vehicles, Long-Term Energy Storage, and CO2 Conversion.

The rapid population growth coupled with rising global energy demand underscores the crucial importance of advancing intermittent renewable energy technologies and low-emission vehicles, which will be pivotal toward carbon neutralization. Reversible solid oxide cells (RSOCs) hold significant promise as a technology for high-efficiency power generation, long-term chemical energy storage, and CO2 conversion. Herein, RSOCs were, for the first time, studied to power electric vehicles. Based on our experimental results, an ideal RSOC stack was established with reasonable assumptions. Subsequently, through analysis and comparison of important merits, such as power densities, energy densities, charging/refueling time, and fuel economy of RSOC-based electric vehicles (RSOCEVs), conventional internal combustor vehicles (ICEVs), and battery-based electric vehicles (BEVs), the advantages and prospects of RSOCEVs were highlighted. Our H2-H2O RSOCs exhibit high electrochemical performances in both fuel cell (peak power density = 1.6 W cm-2 at 750 °C) and electrolysis modes (current density = 2.0 A cm-2 at 1.3 V and 750 °C), along with durable reversible operation under a wide range of conditions. In CO-CO2, our RSOCs achieved excellent performance in fuel cell mode (peak power density = 0.68 cm-2 at 700 °C). Furthermore, a world record current density of 3.4 A cm-2 at 1.5 V and 750 °C was achieved in the CO2 electrolysis mode. Moreover, an assessment of the CO2 electrolysis efficiency was conducted, offering insights for establishing energy storage strategies and mitigating CO2 emissions. Therefore, the RSOC technology has the potential to assume a central role in a future energy system with abundant renewable power generation while mitigating the CO2 released from fossil fuels.

Exploring synergistic and individual causal effects of rare earth elements and renewable energy on multidimensional economic complexity for sustainable economic development

The ongoing global energy transition has highlighted the instrumental role of rare earth elements (REEs) in achieving green growth through the deployment of renewable energy technologies, establishing a hypothetical progressive synergistic association between them. Therefore, testing this hypothetical synergy and its potential causal effects on economic and technological proxies based on empirical foundations becomes imperative in addressing rampant climatic change. First, we employed Deep Learning algorithms to explore the combined effects of this synergy on Multidimensional Economic Complexity (MEC) as an index using panel data of the largest producers of REEs from 1990 to 2023. Second, Temporal Causal Modelling (TCM) was employed to unveil the directional causality between REEs and renewable energy, as well as their causal roles in driving economic complexities. The deep learning models accurately predicted the positive role of this synergistic relationship in promoting overall MEC. Then, the results of TCM reveal that REE production increases renewable energy use and reduces CO2 emissions. Renewable energy promotes Research and Technology complexities while REE production affects them indirectly through renewables. It implies that harnessing this synergy to enhance economic complexities can, in turn, bolster green economic and technological development while mitigating CO2 emissions and addressing pervasive climate change.

Strong electric field at the sharp tips of Cu(OH)2 nanochrysanthemums for selective electrochemical CO2 conversion into ethylene

Electrochemical CO2 reduction reaction (CO2RR) is an attractive approach for the mitigation of CO2 emissions and the production of value-added chemicals. However, it remains a challenge to achieve high selectivity of desirable C2 products like ethylene (C2H4) with high economic value and large market. Herein, we report the fabrication of unprecedented Cu(OH)2 nanochrysanthemums catalyst layer (CL). Interestingly, Cu(OH)2 nanochrysanthemums CL exhibits a C2H4 Faradaic efficiency (FE) of 51.2 ± 0.5% and a FE(C2H4+C2H5OH) of 70.0 ± 0.5% in pH nearly neutral electrolytes. It is worth mentioning that Cu(OH)2 nanochrysanthemums CL achieves the highest FEC2 among documented Cu(OH)2 electrocatalysts. The high FEC2H4 and FEC2 can be attributed to the high electrochemical surface area (ECSA, 21.9 mF/cm2) of Cu(OH)2 nanochrysanthemums. In addition, the wellbalanced hydrophilicity-hydrophobicity of the Cu(OH)2 nanochrysanthemums CL also contributes to the high FEC2H4 and FEC2 by simultaneously satisfying efficient transfer of hydrophobic CO2 and C2H4 as well as hydrophilic H2O and C2H5OH. COMSOL multiphysics simulations and density functional theory (DFT) calculations further suggest that the negatively charged sharp tips of Cu(OH)2 nanochrysanthemums would trigger the accumulation of K+ and offer strong local electric field of 9.8 V/μm, promoting C–C coupling and suppressing hydrogen evolution reaction (HER).

Do female political leaders make the environment greener? Evidence from the United States

PurposeThis study examines the effect of female governors (gender effect) on environmental performance in terms of state-level carbon dioxide (CO2) emissions in United States.Design/methodology/approachThe study used annual data from 1970 to 2020 to investigate the relationship between female political leadership and state-level CO2 emissions. Hypothesis was tested through ordinary least squares regression (OLS). The results of the study were also validated using propensity score matching and a difference-in-difference approach.FindingsThis study provides empirical insights into the relationship between female political leadership and state-level CO2 emissions. The findings indicate that female governors have a significant negative impact on state-level CO2 emissions per capita. These results suggest that female political leadership is associated with a reduction in CO2 emissions per capita at the state level. The results also show that states under the leadership of female governors experience lower levels of CO2 emissions than those with male governors, indicating female leadership’s potential to promote environmental sustainability.Practical implicationsThe findings of this study have practical implications for policymakers, government officials, and other stakeholders involved in the formulation of strategies to promote environmental sustainability. This study highlights the significant role that female political leader play in mitigating CO2 emissions at the state level. It suggests that promoting female in political leadership positions can lead to more environmentally conscious policy decisions and actions, resulting in reduced CO2 emissions per capita. Policymakers should actively encourage women’s participation in leadership roles to utilize their potential contributions to advancing sustainability goals. Furthermore, organizations that focus on environmental issues should prioritize supporting and promoting female leaders who have demonstrated a commitment to environmental sustainability. Ultimately, this study highlights the need for female in political leadership as a potential strategy to address environmental challenges and advance a more sustainable future.Originality/valueThis study pioneers research on the links between female political leadership and state-level CO2 emissions. This study contributes to the literature by emphasizing the potential role of female political leaders in promoting environmental sustainability. Overall, this study enriches the social role and upper echelons theories literature through empirical evidence.

A thorough assessment of mineral carbonation of steel slag and refractory waste

Escalating industrial CO2 emissions necessitate innovative carbon capture and utilization strategies. This study explores the potential of mineral-carbonation of steelmaking slags, particularly White Slag (WS) and various Refractory Wastes (RWs), to mitigate CO2 emissions and valorize industrial wastes. Experiments were performed with waste materials from the production lines at CELSA (Barcelona, Spain). We delved into direct aqueous carbonation, evaluating the performance and characteristics of these wastes under different experimental conditions. Our findings reveal that all slags can effectively sequester CO2. This process is effective not only for pure CO2 but also for diluted flue gases under mild conditions (≤ 100 ºC, ≤ 6 bar). Specifically, WS exhibited peak CO2 sequestration capacities (SC) of 359.79 gCO2/kgslag (pure CO2) and 276.65 gCO2/kgslag (diluted flue gas). In contrast, the RWs presented different kinetic, reaching a maximum SC of 311 gCO2/kgslag after prolonged times. Given the large inhomogeneity of RWs, individual analysis of distinct RW fractions revealed significant variations in carbonation performance. Tundish RW exhibited the highest CO2 sequestration capacity, emphasizing the importance of waste source and mineral composition in the carbonation. Chemical and morphological evaluations confirmed the transformation of CaO to CaCO3, with MgO remaining largely inert. Additionally, the process indicated potential environmental benefits by reducing the mobility of toxic metals, particularly Pb, suggesting an ancillary avenue for waste treatment. This study underscores the utility of CO2 mineralization as a dual-benefit approach within the circular economy framework, offering insights into its application for sustainable waste management and CO2 emission reduction in the steel industry.

Investigation of the potential for electrification of remote areas using parabolic solar collectors in southern Algeria

The dish stirling technology holds great promise as a renewable energy solution for remote and off-grid electric regions, particularly in the southern areas of North Africa. In this research, we conducted simulations of a 100 kw Dish Stirling system to evaluate its feasibility in comparison to photovoltaic technology at five distinct locations in southern Algeria: Adrar (Bordj Badji Mokhtar), Illizi (Djanet), Tamanrasset (Ain Mertoutek), Tindouf, and Bechar. Our findings underscore the substantial potential of Dish Stirling Solar Power technology, with the Sahara region standing out as particularly promising. In this region, the Dish Stirling system consistently outperforms a 100 kw photovoltaic system across all selected locations. The Dish Stirling system achieves an average annual electricity generation of 256 mwh while simultaneously mitigating CO2 emissions by 177 tons annually. Among these locations, Djanet Illizi emerges as the most favorable, with the Dish Stirling system producing an impressive 288.43 mwh annually. This capacity is sufficient to meet the annual energy needs of 230 households, all while maintaining a competitive LCOE of 0.0378 USD/kwh. Comparative analysis with previous research illuminates the remarkable cost-effectiveness of Dish Stirling technology in southern Algeria, primarily due to its abundant direct normal irradiance levels. These findings underscore the immense potential of Dish Stirling systems as a clean and highly efficient energy solution, well-suited for demanding to address the energy needs of remote environments, such as those found in the southern border regions of Algeria.

Assessing the impact of resource efficiency, renewable energy R&D spending, and green technologies on environmental sustainability in Germany: Evidence from a Wavelet Quantile-on-Quantile Regression

One important challenge in the world today is how to reverse the growth of carbon dioxide emissions to save the planet from environmental degradation without putting economic growth at risk. Several measures and initiatives such as resource efficiency, green energy transition, energy technologies, emission control, etc. Have been adopted by several countries worldwide in order to mitigate CO2 emissions. This study investigates the impact of resource efficiency, renewable energy Research and Development (R&D) expenditures, and green technologies towards fostering environmental sustainability in Germany. Using quarterly data spanning from 1974 to 2019, the study applies the Wavelet Quantile-on-Quantile Regression (WQQR) approach. This method embeds a wavelet kernel into quantile-on-quantile regression to capture the time-varying coefficients. The empirical findings reveal a negative impact of resource efficiency, renewable energy R&D expenditures, and green technologies on energy-based carbon intensity. The results further reveal that, with the exception of green technologies, the negative effects of resource efficiency and renewable energy R&D expenditures are stronger in the middle quantiles. The study demonstrates the robustness of these results through the wavelet quantile regression analysis. Finally, the study offers valuable policy implications that align with the United Nations’ Sustainable Development Goals (SDGs) 7 and 13, aiming to achieve a sustainable environment.

Overcoming equilibrium constraints in the reverse water gas shift with counter-current gas–solid flow and oxygen transport in La0.75Sr0.25Cr0.5Mn0.5O3-δ

Utilizing carbon dioxide in the reverse water gas shift (RWGS) reaction (CO2+H2→CO+H2O) is a potential pathway for mitigating CO2 emissions, as the resulting CO can be used to produce valuable products, such as chemicals and fuels. Here, we explore the implementation of the RWGS reaction by solid-oxide redox cycling in a two-reactor moving-bed process with counter-current gas–solid flow. We also develop a method for obtaining design diagrams from the thermodynamic data of the solid oxide utilized for redox cycling. Using this tool and screening the previous literature for relevant thermodynamic data, we identify the perovskite La0.75Sr0.25Mn0.5Cr0.5O3-δ as a highly promising candidate material, and we experimentally determine its non-stoichiometry under conditions relevant for the RWGS. The reaction kinetics are also obtained for its reduction in H2 and its reoxidation in CO2. We observe that the inward diffusion of oxygen into the perovskite grains during reoxidation in CO2 is likely to determine the minimum feasible temperature at which this process can be operated, and we estimate an effective diffusion coefficient of D = 7.7−1.4+1.8 *10−14 cm2 s−1 at T = 550 °C, with an activation energy of 122±4.4 kJ mol−1. Implementing the RWGS with this material in counter-current gas–solid flow is expected to significantly improve the RWGS process by decreasing the operating temperature, enabling continuous gas production, and increasing the gas conversion.

What drives environmental sustainability? The role of renewable energy, green innovation, and political stability in OECD economies

ABSTRACT One possible way to achieve environmental sustainability is by addressing the issue of rising CO2 emissions, which significantly cause climate change by intensifying the greenhouse gas effect. The Organization for Economic Cooperation and Development (OECD), which substantially contributes to global CO2 emissions, necessitates a paradigm shift towards using clean energy sources and promoting green innovations to ensure environmental sustainability. Thus, this study aims to inspect the role of renewable energy use, green technology innovation, political stability, and fiscal decentralization in attaining environmental sustainability by limiting CO2 emissions for seven OECD economies from 2000 to 2019. This study has employed the ‘Cross-Sectional Augmented Autoregressive Distributed Lag and Augmented Mean Group Estimator’ for robust empirical analysis. The results indicate that renewable energy use, political stability, and fiscal decentralization can mitigate CO2 emissions and ensure environmental sustainability in OECD economies. In contrast, green technology innovation exhibits an insignificant effect on CO2 emissions. Furthermore, the moderation effects of fiscal decentralization and political stability exhibit a negative relationship with CO2 emissions. Notably, this study advises OECD nations to encourage regional cooperation to ensure political stability and devolution of fiscal powers to promote green innovation and renewable energy use to achieve sustainable goals.

Decomposition analysis of electricity generation on carbon dioxide emissions in Ghana

This study analyses the factors driving CO2 emissions from electricity generation in Ghana from 1990 to 2020. Employing Logarithmic Mean Divisia Index (LMDI) and Autoregressive Distributed Lag (ARDL) techniques, the research decomposes electricity generation into different factors and assesses their impact on CO2 emissions, considering both short and long-run effects. The LMDI analysis reveals that the total CO2 emissions from electricity generation amount to 3.33%, with all factors contributing positively in each subperiod. Notably, fossil fuel intensity, production, and transformation factors exhibit substantial contributions of about 1.16%, 0.49%, and 0.48%, respectively. Contrastingly, the ARDL results highlight that only electricity intensity and production factors significantly increase CO2 emissions by about 0.20% and 0.09% (0.38% and 0.10%) in the short-run (long-run), while other factors contribute to a reduction in electricity generation emissions. Overall, we conclude that electricity intensity and production factors are the primary drivers of CO2 emissions from electricity generation in Ghana. Nevertheless, effective measures to address all decomposition factors is crucial for effective mitigation of electricity generation CO2 emissions.

Evaluation of a novel fertilizer-drawn forward osmosis and membrane contactor hybrid system for CO2 capture using ammonia-rich wastewater

Chemical absorption is widely employed to capture carbon dioxide (CO2) for addressing climate change. While monoethanolamine (MEA) currently dominates as an absorption solvent, utilizing ammonia-rich wastewater offers advantages such as reduced costs, high absorption capacity, and the generation of ammonium carbamate. This study proposes an innovative fertilizer-drawn forward osmosis (FDFO)-membrane contactor (MC) hybrid system for economically and sustainably mitigating CO2 emissions using ammonia-rich wastewater. First, ammonia-lean synthetic wastewater was concentrated through an FDFO system, using three fertilizers (KCl, monoammonium phosphate, and diammonium phosphate) as draw solutions. While KCl achieved a 45% ammonia dilution, diammonium phosphate yielded the highest concentration approximately 49%. Also, MCs were assessed for CO2 absorption under various operational conditions. Increased liquid concentration and flow rates improved CO2 capture efficiency, whereas higher CO2 flow rates and concentrations resulted in an adverse effect. Furthermore, a simulation study of a hybrid FDFO-MC system was conducted to evaluate the feasibility and potential of the system. The results indicated that the FDFO-MC hybrid system has the potential to efficiently remove CO2 if sufficient concentration and flow rate of ammonia-rich solution was secured at the FDFO outlet. This innovation addresses CO2 emissions and wastewater challenges, adhering to circular economy principles.

Gas-to-Biochar Byproducts of Pyrolysis and Gasification of Star Anise Biomass

In a transition to a circular economy, second-generation biomass energy has come to the forefront. The present study is aimed at characterizing biochar and byproducts of the pyrolysis of star anise residue (ANI) in the N2 and CO2 atmospheres as well as the kinetics and optimal reaction mechanisms based on the Flynn–Wall–Ozawa and Coats-Redfern methods. The ANI pyrolysis involved three stages, with the first one (161.5–559.1°C) as the main phase. The activation energy was lower in the N2 atmosphere than in the CO2 atmosphere (179.44–190.17 kJ/mol). The primary volatile products generated during the ANI pyrolysis were small molecule products (H2O, CO2, CO, and CH4), organic acids, alcohols, and ketones. The atmosphere type exerted a minimal impact on the types of gases released, with the CO2 atmosphere increasing CO and CH4 emissions. The pyrolytic oil of ANI contained a variety of organic compounds, including alcohols, phenols, ketones, acids, sugars, and other nitrogen- and oxygen-containing cyclic compounds, with its predominant compounds being acids, esters, ketones, and sugars. The elevated temperature range of 300–700°C enhanced the charring degree of the ANI biochar. The biochar showed stronger aromaticity in the CO2 atmosphere but better granularity in the N2 atmosphere. This study introduced an innovative perspective by showcasing the potential of ANI as a promising biomass source for energy generation and underscored its abundance, sustainability, and applicability as a raw material in fragrance production. It also emphasized the significance of CO2-reuse technology as a means to mitigate CO2 emissions. The findings of this work offer a theoretical and practical basis for the comprehensive utilization and efficient disposal of star anise residues.