Global Warming Issues Research Articles

Optimal sizing and techno-enviro-economic evaluation of a hybrid photovoltaic/wind/diesel system with battery and fuel cell storage devices under different climatic conditions in Cameroon

Due to advancements in renewable energy technology and their ability to mitigate the issue of global warming, solar and wind energy sources are becoming increasingly popular for power generation. However, the intermittent nature of these sources means that their availability does not always correlate with load fluctuations. Hence, to solve the unpredictability concerns associated with solar and wind energy sources, they may be integrated with storage technologies and conventional energy sources (diesel generators) in a hybrid energy system (HES) to continuously supply the load demand. This paper performs a techno-economic and environmental assessment of hybrid systems integrating photovoltaic (PV), wind turbine generator (WT), and diesel generator (DSL), considering fuel cell (FC) and battery (BAT) storage devices, to supply three non-domestic loads at different locations in Cameroon, namely, Fotokol, Idabato, Kousseri, and Figuil. The Cuckoo Search Algorithm (CSA) is introduced to optimally size the various components of the proposed systems in order to fulfill the load demands in the most cost-effective manner with excellent reliability. The results show that in the short term period, hybrid systems incorporating battery storage devices are more cost effective than fuel cell storage systems. Indeed, the most optimal system found was PV/WT/BAT/DSL at the city of Idabato, with a COE of 0.151$/kWh, 0.180$/kWh, and 0.220$/kWh for high, medium, and low consumers, with corresponding break-even distances of 0 km, 0.14 km, and 0.44 km, respectively. Traditionally, using diesel generator systems for power generation costs 0.469$/kWh, 0.618$/kWh, and 0.766$/kWh, with CO2 emissions of 13694.3 kg/year, 10351.4 kg/year, and 8978.1 kg/year for high, medium, and low consumers, respectively. However, using the PV/WT/BAT/DSL configuration at Idabato in comparison to the conventional diesel generator reduces CO2 emissions in this locality by 94.32%, 95.22%, and 93.79% for high, medium, and low consumers, respectively. On the other hand, the PV/WT/FC/DSL hybrid system at Idabato presents COE of 1.018$/kWh, 1.655$/kWh, and 2.289$/kWh, with saving CO2 emissions of 91.27%, 91.76%, and 94.63% for high, medium, and low consumers, respectively.

Potential reductions of CO2 emissions from the transition to electric vehicles: Thailand’s scenarios towards 2030

The climate crisis has become a significant concern for many worldwide sectors. One of the primary causes of global warming comes from carbon dioxide (CO2) emissions, in which the transport sector is the major emitter, especially from road vehicles. Electric vehicles (EVs) have been seen as the best decarbonization choice to respond to the global warming issue by replacing fossil-fueled engines with electrically driven engines, especially electricity from renewable energy sources. Last year, Thailand’s government unveiled a roadmap with a view to achieving EV production of at least 30% of all auto production in the country by 2030 through the 30@30 policy plan. This study describes the potential reductions of CO2 emissions and their cost resulting from the transition to EVs in Thailand. The CO2 emissions of EVs caused by Thailand’s road vehicle fleet and battery production have been considered, and the forecasting scenarios of the proportion of EVs in 2030 have been studied. In the scenarios, the number of road cars in 2030 was estimated based on the registered vehicle statistics in Thailand. The data on seven-passenger cars powered by gasoline and electricity are used. A potential incentive from the government to encourage the use of EVs is also discussed based on analyzing the cost of carbon.

Development Module of Global Warming Issue to Train Science, Technology, Engineering, and Mathematics (STEM) Literacy

Teaching materials can improve students' skills. Global warming material is important to learn to solve social problems or global issues. Therefore, this study aims to develop an integrated STEM module on global warming material to train learners' STEM literacy. This research method is Research and Development (R&D). The data is analyzed descriptively. N-gain is used to determine module effectiveness and improve students' STEM literacy. The sample in this study was class X which amounted to 36 learners. The results showed that the STEM-based modules developed had criteria suitable for use in the learning process in terms of suitability of the material with STEM with a validation score of 0.75 in the high category (feasible), and aspects of the feasibility of teaching materials which were divided into several assessments with a score of 0.87 in the very high category (very feasible), module design with a score of 0.86 in the very high category (very feasible) and the language component with a score of 0.85 in the very high category (very feasible), The average perception of learners towards the use of modules in the overall learning process is 70.53 medium categories. STEM-based modules are suitable to be used as an alternative source of learning global warming in physics learning to train students' STEM literacy.

Synthesis of n-butanol-rich C3+ alcohols by direct CO2 hydrogenation over a stable Cu–Co tandem catalyst

The direct conversion of CO2 into liquid fuels and chemical heterogeneous catalysts is considered a promising route to mitigate global warming issues. However, the production of n-butanol-rich C3+ alcohol from CO2 remains a significant challenge. Herein, we demonstrate that a Cu-rich bimetallic Cu–Co catalyst can achieve an unprecedentedly high space-time yield (STYC3+OH) of 80.8 mg g−1 h−1. The decoration of Co nanoparticles onto the dendritic Cu substrate established a crucial balance between CHx and CH3O* and regulated C–C coupling, which is a prerequisite for C3+ alcohol synthesis. We provide new mechanistic insights into n-butanol synthesis involving the C–O bond dissociation of an acetaldehyde intermediate on the interfacial Cu–Co site and subsequent C–C bond formation on the Cu site. Furthermore, the Cu–Co catalyst exhibited exceptional stability up to 1000 h by effectively suppressing re-oxidation and carbon deposition. The Cu–Co catalyst has great potential for large-scale CO2 hydrogenation to C3+ alcohol owing to its high selectivity and remarkable stability.

Role of nuclear energy, geothermal energy, agriculture, and urbanization in environmental stewardship

The global issue of atmospheric variations and global warming caused by diverse anthropogenic behaviors is a global concern. There is apprehension about preserving an uncontaminated atmosphere and attaining optimal nuclear and geothermal energy utilization with agriculture sector development. In this regard, this paper investigates the influence of nuclear energy, geothermal energy, agriculture development, and urbanization on carbon emissions and ecological footprint from 1990Q1 to 2019Q4 in the case of China. The findings of unit root tests reveal that all variables are stationary at first integration order, and cointegration test findings confirm the presence of long-run relationships among series. The quantile autoregressive distributive lag (QARDL) method findings demonstrate that nuclear energy, geothermal energy, and urbanization statistically correlate with CO2 emissions and ecological footprint across all quantiles, indicating that these determinants have contributed to environmental degradation. Whereas agricultural development has a statistically significant and negative influence on the environment, implying that agriculture has a pollution-mitigation impact. Based on these empirical findings, several policy implications are presented to preserve environmental quality to achieve the 2030 Sustainable Development Goals (SDGs) target.

Effects of surface chlorine atoms on charge distribution and reaction barriers for photocatalytic CO2 reduction

Photocatalytic CO2 reduction to produce high value-added carbon-based fuel has been proposed as a promising approach to mitigate global warming issues. However, the conversion efficiency and product selectivity are still low due to the sluggish dynamics of transfer processes involved in proton-assisted multi-electron reactions. Lowering the formation energy barriers of intermediate products is an effective method to enhance the selectivity and productivity of final products. In this study, we aim to regulate the surface electronic structure of Bi2WO6 by doping surface chlorine atoms to achieve effective photocatalytic CO2 reduction. Surface Cl atoms can enhance the absorption ability of light, affect its energy band structure and promote charge separation. Combined with DFT calculations, it is revealed that surface Cl atoms can not only change the surface charge distribution which affects the competitive adsorption of H2O and CO2, but also lower the formation energy barrier of intermediate products to generate more intermediate ∗COOH, thus facilitating CO production. Overall, this study demonstrates a promising surface halogenation strategy to enhance the photocatalytic CO2 reduction activity of a layered structure Bi-based catalyst.

A novel FFA‐GWO‐based optimization paradigm for solving a dynamic economic emission dispatch in power plants

AbstractThermal power plants are the primary components of the electrical energy production industry. These plants come with certain challenges such as the production of harmful gases causing environmental pollution. This adds to global warming issues that are dangerous for the earth's ecosystem. Another crucial aim is the least cost operation of these power plants. Combining both of these results in the formulation of the Dynamic Economic Emission Dispatch (DEED). This is a multi‐objective, constrained, dynamic, complex, and non‐linear optimization problem. Traditional methods are insufficient to undertake the complexities of DEED due to challenges such as high computational requirements and local optimal solutions. Hence, for obtaining an optimal or near‐optimal solution to such a complex problem, a metaheuristic technique is greatly needed. Metaheuristic techniques offer several benefits to solving complex problems such as being robust, efficient, and overall, less affected by an increase in problem size. In this work, a novel hybrid Firefly Optimization Algorithm (FFA)—Grey Wolf Optimization Algorithm (GWO) has been proposed to solve the DEED problem. The complexity of the DEED problem is undertaken by involving constraints like power limits, power balance, and transmission losses. FFA‐GWO was applied on 5, 10, and 15‐unit standard test systems to meet 24‐h load demands. The optimal costs obtained in 5, 10, and 15‐unit standard test systems are 32264$, 1394212.615$, and 465373.448$ respectively. The comparison of results shows that the proposed framework surpasses the other methodologies in terms of reduced fuel cost and emissions.

GREEN ECONOMY IN SHARIAH ECONOMICS PERSPECTIVE IMPROVING COMMUNITY WELFARE

The emergence of the green economy due to the issue of global warming is caused bythe environmental crisis caused by a shift in pragmatic human lifestyles. This condition requireseverything to be fast and easy with the use of packaged products which results in a lot of usedproduct waste that is not environmentally friendly. Therefore, the concept of going greenemerged, namely the concept of green economy as an environmentally friendly concept that isin accordance with Islamic economic principles to support environmental development (proenvironment) which has an influence on the development of an economic system that is ableto improve the welfare of society.This research is research aimed at analyzing the greeneconomy from an Islamic economic perspective to improve community welfare. This researchis library research (library research), Data analysis techniques using the Milles and Hubermanmodel include: (1) data reduction, (2) data display, and (3) conclusion drawing. Results researchBased on the discussion it can be concluded that: concept green economyor green economy islow carbon economic activity, saves resources (resource efficient), and is sociallyinclusive/socially inclusive, where this concept is in accordance with Islamic economicprinciples, namely Islamic Eco-Ethics consisting of several principles basic Islamic ethics suchas al-adl (justice), maslahah (public needs), urf (customs), istishlah (improvement), and i'tidal(harmony), so that the green economy is a form of economic improvement that is in harmonywith nature in achieving the benefit and well-being.Key words: green economy, Islamic economy, community welfare

Upgrading catalytic properties of green synthesized TiO2 for green fuel production from apricot seeds oil

The ongoing energy crisis and global warming issues have pushed the research community to search for sustainable energy supplies such as biodiesel (methyl esters). In this regard, inedible oils which are not consumed by humans could be potential sources for methyl esters production. Herein, the methyl esters were produced by trans-esterifying the apricot seeds oil (ASO) employing series of green synthesized (mediated by banana peel extract) TiO2 based NiO-TiO2 heterogeneous nano-catalysts with varying loadings of NiO (5, 10 and 15 by wt%). The as-prepared catalysts were characterized using advanced techniques like FT-IR, XRD, SEM and FE-SEM. These studies established the successful impregnation of NiO with TiO2 NPs. The efficiency of NiO-TiO2 with 10 wt% of NiO loading calcined at 500 °C was superior due to the highest biodiesel yield compared to other nano-catalysts. The parametric study of transesterification reaction to yield methyl esters adapting this catalyst revealed the maximum yield (93.4 %) with MeOH: oil and catalyst loading of 20:1 and 2 wt% correspondingly in 1 h at 55 °C. GC–MS analysis was executed for investigating and confirming the composition of obtained methyl esters at optimized conditions. Furthermore, the heterogeneous catalyst was reusable for five cycles for transesterification of ASO. The kinetic investigations showed that transesterification of ASO was compatible with pseudo-first order model. In addition, fuel characteristics such as calorific and acid value were measured by using titrations and bomb calorimeter respectively and compared with ASTM6751 and EN14214 standards.

Rapid Estimation of Battery Storage Capacity through Multiple Linear Regression

Due to global warming issues, the rapid growth of electric vehicle sales is fully expected to result in a dramatic increase in returned batteries after the first use. Naturally, industries have shown great interest in establishing business models for retired battery reuse and recycling. However, they still have many challenges, such as high costs from the logistics of returned batteries and evaluating returned battery quality. One of the most important characteristics of a returned battery is the battery storage capacity. Conventionally, the battery’s energy capacity is measured through the low current full charging and discharging process. While this traditional measurement procedure gives a reliable estimate of battery storage capacity, the time required for a reliable estimate is unacceptably long to support profitable business models. In this paper, we propose a new algorithm to estimate battery storage capacity that can dramatically reduce the time for estimation through the partial discharging process. To demonstrate the applicability of the proposed algorithm, cylindrical and prismatic cells were used in the experiments. Initially, five indicators were selected from the voltage response curves that can identify battery storage capacity. Then, the five indicators were applied to principal component analysis (PCA) to extract dominant factors. The extracted factors were applied to a multiple linear regression model to produce a reliable estimation of battery storage capacity.

The Impact of Environmental Disclosure on Market Performance: An Empirical Study of Jordanian Listed Industrial Companies

The world is currently grappling with the daunting environmental issue of global warming and climate change, which pose a significant threat to the future of our planet from various perspectives. Increased public awareness and concern over the detrimental effects of these problems have resulted in the creation of new environmental regulations. One important aspect of corporate governance that contributes to addressing this challenge is environmental accounting. By embracing the potential of environmental accounting, businesses can work towards achieving sustainable growth and development. The study aimed to investigate the impact of environmental disclosure on market performance in Jordanian industrial companies listed on the Amman Stock Exchange. The descriptive analytical method was relied on to achieve the study’s objectives. The data was collected through annual reports in addition to the financial statements of a group of industrial companies listed on the Amman Stock Exchange, which met the requirements of environmental disclosure, which were (43) industrial companies during the period (2017-2021). The special data in the study sample were analyzed using the statistical analysis software E-views. The arithmetic means standard deviation, and each of the upper and lower values was extracted in addition to using multiple linear regression analysis. The study concluded that there is a statistically significant effect of the environmental disclosure in both the market value and the stock turnover rate, in addition to Tobin’s Q ratio in the industrial companies surveyed. According to the findings, industrial companies in Jordan should be encouraged to become more interested in and open about their environmental activities. This is because being open about these activities helps them get more investments, start their financing and investment operations, increase their market value, and increase their investment market share.

Constructing C-doped TiO2/β-Bi2O3 hybrids Z-scheme heterojunction for enhanced CO2 photoreduction

Rational fabricating advanced photocatalysts to recycle CO2 into solar fuel is one of the most promising approaches to simultaneously address energy shortages and global warming. TiO2 has been widely used in photocatalytic CO2 reduction due to its abundant reserves, non-toxicity and harmlessness etc. However, it remains significantly challenging for practical applications due to the fast electron-hole recombination. Herein, we design a direct TiO2 based Z-Scheme heterojunction by self-assembly of C-doped TiO2 nanoparticles on 3D hierarchical petal of flower-like β-Bi2O3 (C-TiO2/β-Bi2O3). In situ electron paramagnetic resonance tests, in situ X-ray photoelectron spectroscopy and theoretical calculations reveal that electrons are transferred from β-Bi2O3 to C-TiO2 due to the formation of Z-Scheme heterojunction, which greatly accelerates the separation of photogenerated carriers to promote efficient CO2 photoreduction. Ultimately, the optimal heterojunction shows significantly enhanced photocatalytic activity for CO2 reduction to CO (31.07 μmol g–1 h−1) compared to the pure TiO2 (3.28 μmol g–1 h−1) without using any photosensitizers and sacrificial agents. This work provides a unique insight to design direct Z-Scheme heterojunctions and delivers a promising photocatalyst for overcoming global warming and energy-supply issues.

The construction of subjectivities and enemies in global warming: searching for the political climate issue in Swedish Election Campaigns, 1988–2014

ABSTRACT It has been argued that the issue of global warming has become incorporated into a postpolitical condition that has deprived it of a proper political subject. In this article, the depoliticizing process is examined through a historical analysis of Swedish election campaigns, 1988 to 2014, a domain that traditionally features political language and politicizations. The analysis shows how the rhetoric of political parties was characterized by an increasingly universalizing language which made it problematic to name a political subject, and how the enemy of global warming was constructed as an outsider that threatened the current order. The article argues for the need to re-politicize the climate issue by understanding climate crises as social crises; that is, crises that can be properly politicized.

Briefed on the development and progress of CCUS projects in China, USA, Western Europe, Russia, Norway, India, and Indonesia: a journal review

The global commitment to manage climate change issues is getting stronger and stronger. Therefore this review is carried out with the objective to obtain recent progress of efforts on emission control and handling through CCUS by various countries around the world. This review is carried out to highlight the development of carbon capture utilization and/or storage (CCUS) in China, the USA, and India, as these countries are known to be the most energy consumption countries. Its campaign to reduce emissions will contribute significantly to the effort of managing the global warming issue. The method used in this study is a literature review on the policies, studies, and projects mainly in China, and several other countries for comparison. The review found that although China is relatively late in doing such activities on climate change, but the progress is significantly faster than the others. The numbers of studies and patents are much higher than other countries, and the central and local governments issued a number of policies to help encourages the industries. The USA is known as one of the leading countries implementing CCS/CCUS and still creating incentive policies. European, Russian, and Indian countries pay serious attention to this effort and implement it while Indonesia as a non-industrial country is catching up.. From this literature research, it can be concluded that the technology for implementing CCUS is still at a high cost so policy and government funding support is needed as well as non-traditional sources of capital source such as green funding, carbon trading, etc.

Optimal mixing method of ZnZrOx and MOR-type zeolite to prepare a bifunctional catalyst for CO2 hydrogenation to lower olefins

In recent years, the issue of global warming caused by CO2 emissions has become a critical problem and poses a worldwide challenge. To address this issue, we have developed a bifunctional catalyst that can convert CO2 to lower olefins in a single stage. Our bifunctional catalysts are a combination of two catalysts, a CO2-to-methanol hydrogenation catalyst (Zn-doped ZrO2, named ZnZrOx) and a methanol-to-olefin catalyst (MOR-type zeolite, named MOR104). In this research, we examined the impact of various mixing modes of the two catalysts on product distribution. We tested four different mixing modes using a down-flow fixed bed reactor: (a) ZnZrOx in the upper layer and MOR104 in the lower layer, (b) catalysts were mixed randomly after being pelletized separately, (c) MOR104 in the upper layer and ZnZrOx in the lower layer, and (d) granulated catalyst produced by physically mixing both catalyst powders. Our findings indicated that the best performance was achieved with catalyst (d), where the two catalysts were mixed in close proximity. This proximity resulted in efficient supply of methanol produced on ZnZrOx to MOR104. In other words, the MTO reaction in MOR104 efficiently consumed methanol molecules produced via equilibrium-limited CO2-to-methanol hydrogenation. When ZnZrOx and MOR104 were thoroughly mixed, the conversion of CO2 to methanol shifted towards the product side, resulting in a greater overall utilization of CO2. Furthermore, the bifunctional catalyst we developed was stable for six hours. Since there have been few studies of bifunctional catalysts containing zeolites other than ZSM-5 and SAPO-34, this study opens up new opportunities for bifunctional catalysts specialized for one-pass hydrocarbon synthesis through CO2 hydrogenation.

The future trajectory of carbon emissions in the process of carbon neutrality in South Korea

The excessive use of fossil energy in industrialization has caused the frequent occurrence of global warming and environmental pollution issues, which seriously threaten the sustainable social and economic development of South Korea and other countries. In response to the international community's call to effectively address climate change, South Korea has announced achieving carbon neutrality by 2050. In this context, this paper takes the carbon emission of South Korea from 2016 to 2021 as a sample and focuses on using the GM(1,1) model to predict the carbon emission change trajectory of South Korea in the process of achieving carbon neutrality. The results show: first, in the process of carbon neutrality, South Korea's carbon emissions show a downward trend, with an average annual rate of 2.34%. Second, by 2030, carbon emissions will decline to 502.34 Mt CO2e, down about 26.79% from the 2018 peak. By 2050, South Korea's carbon emissions will decline to 312.65 Mt CO2e, down about 54.44% from the 2018 peak. Third, it is difficult for South Korea to achieve its carbon neutrality target by 2050 based solely on its forest carbon sink storage capacity. Therefore, this study is expected to provide a reference for improving the carbon neutrality promotion strategy in South Korea and strengthening the construction of relevant systems of carbon neutrality, and so can provide some reference for other countries, including China, to improve policy design to promote the green and low-carbon transformation of the global economy.

Employees’ Perceptions of Green Supply-Chain Management, Corporate Social Responsibility, and Sustainability in Organizations: Mediating Effect of Reflective Moral Attentiveness

(1) Background: The increasing level of concern over reduction non-renewable resources, global warming, pollution, and social issues has led firms to initiate green and social activities. Furthermore, there is limited empirical evidence on the potential impact of green initiatives, corporate social responsibility (CSR), and reflective moral attentiveness (RMA) on sustainable performance. The purpose of this study was to investigate the mediating effect of reflective moral attentiveness (RMA) on the relationship between green supply-chain-management practices (GSCM) and CSR on sustainable performance. Based on the natural-resource-based view, stakeholder resource-based view, and signaling theory, this study investigated the role of GSCM practices and CSR in sustainable performance using cross-sectional data from the manufacturing and services industries from Khyber Pakhtunkhwa province, in Pakistan. (2) Methods: Using a non-probability convenience-sampling method, 500 employees were selected from the firms which are listed on the Pakistan stock exchange (PSE) and questionnaires were distributed. Complete questionnaires were received from 380 employees and used in the analysis, yielding a response rate of 76%. Partial least squares structural equation modeling (PLS-SEM) software was used for the confirmatory-factor analysis (CFA) and the testing of the hypotheses. The CFA results revealed the reliability and validity of the questionnaires. (3) Results: The results of the structural model (hypotheses testing) show that four attributes of GSCM practices (internal environmental management, green purchasing, cooperation with customers, and eco-design) have a positive influence on sustainable performance, while investment recovery and CSR were found to be insignificant. Moreover, there were significant and positive influences of GSCM and RMA on sustainable performance. On the other hand, control variables, such as gender, experience, and age, were found to have no significant role in sustainable performance. A further analysis revealed that reflective moral attentiveness mediated the relationship between GSCM, CSR, and sustainable performance. (4) Conclusions/implications: This study has several implications for green services and manufacturing firms specifically and for practitioners, researchers and academics in general. The innovation and novelty of this study lie in its determination of the contribution of RMA, GSCM, and CSR to achieving sustainable performance. Firms can improve their clean production activities by incorporating this model as a strategy. Future studies may add moderators and mediators to explore the impact of CSR and GSCM practices upon sustainability.

Politics of climate risk management in local government: a case study of the municipality of Stavanger

The case study presented in this paper was conducted to study the politics of local-level climate risk management and discuss these politics' implications for responses to climate change and democratic deliberation. Local government plays an important role in the response to climate change, in particular with reference to coping with unwanted consequences of climate change, such as more frequent and intense extreme weather events, including torrential rain and flooding. Climate risk management is an approach that local government can adopt to deal with these unwanted consequences. To investigate the politics of local-level climate risk management, we conducted a case study of the municipality of Stavanger in Norway. In analyzing this case study, we drew on literature on the securitization of climate change, in particular, that of risk-based securitization of climate change produced by governmental power. The analysis given here is derived by applying the concept of risk logic understood as the translation of unwanted consequences of climate change into climate risk together with the actions and use of tools influenced by the discipline of risk analysis thereby entailed. Risk logic manifests in political discourse, actors, and tools. In this case study, the justification for risk logic on unwanted consequences of climate change at the local level comes from national-level laws and regulations. Moreover, climate risk management is translated into existing bureaucratic routines, organizational structures, and the activities of professionals. Risk tools play an essential role in making unwanted consequences of climate change governable and can manifest as a consequence of risk logic or can convey risk logic. The analysis implies that the securitization of climate change based on governmental power at the local level has a depoliticizing effect on the issue. Moreover, the unique characteristics of unwanted consequences of climate change fade as climate risk is seen as a risk driver to be factored into existing and well-known risks, and thereby normalizes the situation. Finally, the focus on the cause of climate change seems to diminish because safety is a function of the referent objects, and the response thereby becomes decoupled from the wider issue of global warming.

Combustion Characteristics of a Novel Ammonia Combustor equipped with Stratified Injection for Low Emissions

Ammonia – a carbon-free fuel- is being considered by various research groups and organizations as a potential alternative fuel to tackle some global warming issues of the 21st century. However, ammonia faces some challenges as a fuel, particularly, the production of unwanted NOx and unburned ammonia traces at the back end of combustion systems accompanied by unstable flame regimes. Therefore, new concepts are currently being developed to address these challenges whilst also providing stable, high-power operation. This work presents a newly designed stratified combustion system for gas turbines capable of operating with both premixed and stratified modes. The system has been initially evaluated using these two modes employing solely hydrogen and ammonia. Increase of hydrogen stratification resulted in the reduction of NO and NO2, while N2O slightly increased due to the reduction of fuel in the premixed system. Further tests were conducted to evaluate the potential of the systems to replace fossil fuels. Previous work done using methane as the fuel-to-be-replaced has shown interesting trends in terms of emissions and stability. Thus, to progress on the subject, the work conducted here attempted propane/ammonia/hydrogen using this innovative strategy. Results denoted how stratification has a strong impact on NOx production at the flame front, whilst the mechanism of flame stabilization of the new burner enables large operability regions under a great variety of fuel combinations. Strategic injection setups were identified, whilst the best propane/ammonia/hydrogen blends for stability and emissions reduction are also detailed for further implementation in larger systems.

Carbon Dioxide Cycloaddition to Epoxides Promoted by Nicotinamidium Halide Catalysts: A DFT Investigation.

The utilization of CO2 as building block for the production of cyclic carbonate is a promising route to simultaneously mitigate the global warming issue and obtain valuable commercial chemicals. In this work, the activity of nicotinamidium halide catalysts towards the CO2 conversion into cyclic carbonate has been explored by means of density functional theory (DFT) calculations. DFT calculations support the ability, suggested experimentally, of the pyridium α-C-H proton of the catalysts to activate the epoxide ring via a hydrogen bond. Interestingly, DFT calculations underline the involvement of the n-octyl substituent of the pyridyl ring in the epoxide activation, while the hydrogen atom of the amide group N-H is rather involved in the stabilization of the iodide trough electrostatic interactions. Moreover, the replacement of the pyridium α-C-H proton with the bulkier methyl group leads to a different reaction mechanism. The calculated energy barriers well reproduce the experimental trends of the studied catalysts, and the computed activation barrier of 29.0 kcal/mol, relative to the ring opening step of the most active catalyst, is in line with the experimental working temperature of 80 °C. Those results shed light on the CO2 fixation reaction contributing to the development of more efficient catalytic systems.