Search Results (943)

Biomass combustion for the production of electricity and heat remains one of the most widespread renewable energy technologies. Biomass is commonly utilized in fluidized bed combustion systems. Over the years, numerous issues related to the preparation and combustion of biomass in fluidized beds have been identified, including fouling and slagging, which involve the formation of deposits. These phenomena can be mitigated through various methods, including design modifications to boilers, the application of additives, and the careful selection and classification of fuel. Several fuel indices have been proposed to predict the behavior of fuels in terms of their tendency to cause fouling and slagging. Most of these indices were developed for fossil fuels, and the discrepancies between them suggest that although these indices are widely applied, their applicability to agricultural residues, such as straw, remains uncertain. Researchers working in this field emphasize the need for further research, particularly focusing on the comparison of developed indices with the results of biomass combustion at both laboratory and industrial scales. In this study, ten assortments of straw sourced from Poland were selected, and chemical composition analyses were conducted to determine selected fuel indices. The analyzed straw samples were then combusted in a 100 kWₜₕ laboratory-scale circulating fluidized bed unit. Using a specialized austenitic steel probe, the growth rate of the deposit was measured. The collected deposit masses for each straw type were then compared with the calculated fuel indices. The best correlation between the interpretation of the index values and the deposit mass on the probe was observed for the Rs index. However, due to the low sulfur content of straw, Rs numerical interpretation was not adequate. Overall, the indices indicating both good correlation coefficients and an appropriate numerical interpretation for fouling tendency were B/A, Fu, and Cl. Full article

Biomass is a key energy resource in the current context of climate and energy crises, due to its lower carbon footprint compared to fossil fuels. However, wood-based energy presents several drawbacks: public health concerns related to pollutant emissions from combustion, and questions about the sustainability of the resource given the increasing demand for cleaner fuels. This study investigates the combustion of mixtures of wood pellets (WPs) and barley straw pellets (BSPs) in a domestic biomass boiler, with the aim of evaluating how such blends affect pollutant emissions and energy production under standard boiler operation, without modifications. Pellets were characterized using a bomb calorimeter and thermogravimetric analysis (TGA), while gaseous and particulate emissions were measured at the chimney using gas analyzers and an Engine Exhaust Particle Sizer (EEPS), respectively. The results show that high BSP proportions (>50%) are not compatible with domestic biomass boilers, as they led to a significant increase in gaseous pollutant emission. However, blends with moderate BSP shares (10 and 25%) can be successfully used, offering benefits in terms of reduced pollutant emissions and improved sustainability. Additionally, infrared and high-speed cameras were installed above the boiler furnace, equipped with an optical window, to provide new insights into the combustion process. Full article

At the international level, new measures, policies, and technologies are being developed to reduce greenhouse gas emissions and, more broadly, air pollutants. Road transportation is one of the main contributors to such emissions, as vehicles are extensively used in logistics operations, and many fleet owners of fossil-fueled trucks are adopting new technologies such as electric, hybrid, and hydrogen-based vehicles. This paper addresses the Hybrid Fleet Capacitated Vehicle Routing Problem with Time Windows (HF-CVRPTW), with the objectives of minimizing costs and mitigating environmental impacts. A mixed-integer linear programming model is developed, incorporating split deliveries, scheduled arrival times at stores, and a carbon cap-and-trade mechanism. The model is tested on a real case study provided by Decathlon, evaluating the performance of internal combustion engine (ICE), electric (EV), and hydrogen fuel cell (HV) vehicles. Results show that when considering economic and emission trading costs, the optimal fleet deployment priority is to use ICE vehicles first, followed by EVs and then HVs, but considering only total emissions, the result is the reverse. Further analysis explores the conditions under which alternative fuel, electricity, or hydrogen prices can achieve competitiveness, and a further analysis investigates the impact of different electricity generation and hydrogen production pathways on overall indirect emissions. Full article

The growing dependence on fossil fuels has raised concerns over energy security, resource depletion, and environmental impacts, driving the need for renewable alternatives. Coffee husk, a widely available agro-industrial residue, represents an underutilized feedstock for biodiesel production. In this study, biodiesel was synthesized from coffee husk oil using a two-step transesterification process to address its high free fatty acid content (21%). Physicochemical analysis showed that Coffee Husk Oil Methyl Ester (CHOME) possessed a density of 863 kg m⁻³, viscosity of 4.85 cSt, and calorific value of 33.51 MJ kg⁻¹, compared to diesel with 812 kg m⁻³, 2.3 cSt, and 42.4 MJ kg⁻¹. FTIR analysis confirmed the presence of ester carbonyl and C–O functional groups characteristic of CHOME, influencing its combustion behavior. Engine tests were then conducted using B0, B10, B30, B50, and B100 blends under different loads, both with and without fuel preheating. Results showed that neat CHOME (B100) exhibited 11.8% lower brake thermal efficiency (BTE) than diesel, but preheating at 95 °C improved BTE by 5%, with preheated B10 slightly surpassing diesel by 0.5%. Preheating also reduced brake-specific fuel consumption by up to 7.75%. Emission analysis revealed that B100 achieved reductions of 6.4% CO, 8.3% HC, and 7.0% smoke opacity, while NOx increased only marginally (2.86%). Overall, fuel preheating effectively mitigated viscosity-related drawbacks, enabling coffee husk biodiesel to deliver competitive performance with lower emissions, highlighting its potential as a sustainable waste-to-energy fuel. Full article

Syngas, a renewable fuel primarily composed of hydrogen and carbon monoxide, is emerging as a viable alternative to conventional fossil fuels in internal combustion engines (ICEs). Obtained mainly through the gasification of biomass and organic waste, syngas offers significant environmental benefits but also presents challenges due to its lower heating value and variable composition. This review establishes recent advances in understanding syngas combustion, chemical kinetics, and practical applications in spark-ignition (SI) and compression-ignition (CI) engines. Variability in syngas composition, dependent on feedstock and gasification conditions, strongly influences ignition behavior, flame stability, and emissions, demanding detailed kinetic models and adaptive engine control strategies. In SI engines, syngas can replace up to 100% of conventional fuel, typically at 20–30% reduced power output. CI engines generally require a pilot fuel representing 10–20% of total energy to start combustion, favoring dual-fuel (DF) operation for efficiency and emissions control. This work underlines the need to integrate advanced modelling approaches with experimental insights to optimize performance and meet emission targets. By addressing challenges of fuel variability and engine adaptation, syngas reveals promising potential as a clean fuel for future sustainable power generation and transport applications. Full article

To encourage the use of alternative fuels while limiting the use of fossil fuels, researchers have focused on using more environmentally friendly fuels. Furthermore, the goal is to improve engine performance to increase energy efficiency. A four-stroke, single-cylinder, diesel engine with a common rail fuel injection system runs with diesel, biodiesel, and biodiesel–alcohol fuel blends. The tests were performed using a constant engine speed of 2000 rpm and three different gas pedal positions (20%, 50% and 80%). It was found that maximum cylinder gas pressure increased in all test fuels with increased gas pedal position (GPP) and advanced injection start time. In general, the maximum heat release rate increased in blended fuels compared to diesel fuel. In addition, it was seen that advanced injection timings caused an increase in ignition delay in all fuel types. In the same test conditions, it was observed that biodiesel–alcohol fuel blends caused an increase in ignition delay by more than 10% compared to diesel fuel (D100), while shortening combustion duration (CD) by more than 10%. A decreasing trend in CO and HC emissions was observed in the use of biodiesel fuel compared to diesel fuel. With the use of biodiesel–alcohol fuel blends, CO₂ emissions tend to decrease. Advanced injection timings caused high NO emissions. Full article

The steel industry is a significant contributor to global CO₂ emissions due to the highly energy-intensive nature of its production processes. Specifically, steel production involves the conversion of iron ore into steel through processes such as the blast furnace method, which result in significant greenhouse gas emissions due to the combustion of fossil fuels and the chemical reactions involved. To address this challenge, Carbon Capture Utilization and Storage (CCUS) technologies are essential for reducing emissions by capturing CO₂ at its source, preventing its release into the atmosphere. This study focuses on a French steel plant with an annual production capacity of 6.6 million tons of steel and seeks to optimize the chemical absorption process by using a 30 wt.% MonoEthanolAmine (MEA) aqueous solution. To the authors’ knowledge, studies on this solvent, widely used for treating other types of flue gases, are still not present in the literature for the application to this gaseous stream. The goal is to minimize the thermal energy required for solvent regeneration by optimizing some key parameters. Additionally, an economic analysis is carried out, with a particular focus on different achievable CO₂ recovery ratios, with costs quantified as 102.48, 104.47, and 224.36 [$/t CO₂ removed] for 90%, 95%, and 99% CO₂ recovery, respectively. Full article

This review covers the current state, challenges, and future directions of catalytic combustion technologies for mitigating fugitive methane emissions from the fossil fuel industry. Methane, a potent greenhouse gas, is released from diverse sources, including natural gas production, oil operations, coal mining, and natural gas engines. The paper details the primary emission sources, and addresses the technical difficulties associated with dilute and variable methane streams such as ventilation air methane (VAM) from underground coal mines and low-concentration leaks from oil and gas infrastructure. Catalytic combustion is a useful abatement solution due to its ability to destruct methane in lean and challenging conditions at lower temperatures than conventional combustion, thereby minimizing secondary pollutant formation such as NO_X. The review surveys the key catalyst classes, including precious metals, transition metal oxides, hexa-aluminates, and perovskites, and underscores the crucial role of reactor internals, comparing packed beds, monoliths, and open-cell foams in terms of activity, mass transfer, and pressure drop. The paper discusses advanced reactor designs, including flow-reversal and other recuperative systems, modelling approaches, and the promise of advanced manufacturing for next-generation catalytic devices. The review highlights the research needs for catalyst durability, reactor integration, and real-world deployment to enable reliable methane abatement. Full article

Compared with other fossil fuels, the combustion of natural gas releases fewer pollutants, with carbon dioxide being the main emission. As the need for environmental protection increases, gas combustion technology has been progressively developed, working to improve combustion efficiency and reduce harmful emissions. This study utilized computational fluid dynamics to conduct a numerical simulation of gas burners, establishing a physical model on the basis of the standard structural dimensions of the burners. This research focused on investigating the impacts of the excess air ratio, air temperature, and fuel load on combustion characteristics and nitrogen oxide emission levels. These results indicate that although increasing the excess air ratio can effectively reduce nitrogen oxide generation, it adversely affects the combustion efficiency. Additionally, a decrease in air temperature tends to reduce nitrogen oxide emissions, but adaptive adjustments to the combustion system are needed to sustain efficiency. While reducing the fuel load contributes to lower nitrogen oxide emissions, it compromises the combustion efficiency. Full article

Despite long-standing evidence linking fossil fuel combustion to greenhouse gas and climate change effects, and the growing advocacy for reductions and regulatory limits on their use, fossil fuel corporations remain hugely profitable and influential. In response to scientific evidence linking Big Oil’s corporate activities directly to climate change impacts, tactics favoured by Big Tobacco to medical evidence linking smoking to cancer appear to have also been adopted by Big Oil in responding to the Intergovernmental Panel on Climate Change (IPCC) findings. To examine some of these response strategies, a bespoke corpus was compiled from sustainability reports by a sample of three Big Oil corporations over a twenty-year period corresponding to the IPCC’s publication of the third through sixth Assessment Reports. This corpus is statistically and linguistically analyzed for representations and accounts by Big Oil for its activities and how, if at all, scientific evidence is addressed linking fossil fuel extraction and use to the findings of the IPCC. By highlighting corporate response strategies and preferred narrative accounts to the IPCC evidence, the aim is to equip policy- and decision-makers with key insights to develop more effective counter-narratives to facilitate scientific communications in this critical policy space. Full article

Vanadium is a transition metal whose environmental presence has increased due to human activities such as fossil fuel combustion and industrial processes. A central mechanism of its toxicity involves mitochondrial dysfunction, as vanadium exposure disrupts energy metabolism, enhances reactive oxygen species (ROS) generation, and triggers oxidative stress, ultimately leading to genetic damage and alterations in cellular signaling. These mitochondrial alterations contribute to its potential carcinogenic, immunotoxic, and neurotoxic properties, affecting multiple systems, including the neurological, renal, immune, and reproductive systems. Since there are no specific treatments for vanadium intoxication, natural compounds—particularly plant-derived metabolites with antioxidant, mitochondrial-targeted, and chelating properties—have been investigated as potential therapeutic agents to counteract its toxicity. In this context, simple models such as the nematode Caenorhabditis elegans (C. elegans), the fruit fly (Drosophila melanogaster), and the zebrafish (Danio rerio) have emerged as valuable experimental systems for studying vanadium-induced mitochondrial dysfunction and evaluating protective strategies. These organisms offer key advantages, including a short life cycle, ease of handling, and conservation of essential biological pathways with mammals, making them effective tools in environmental toxicology. The aim of this review is to outline the mitochondrial-related toxic effects of vanadium across different biological models and to explore plant-based therapeutic approaches capable of mitigating its harmful health impacts. We also propose the use of simple models, such as D. melanogaster, D. rerio, and, most notably, C. elegans, as versatile and complementary experimental platforms to advance research in this field. Full article

Carbonaceous aerosols represent a significant component of atmospheric aerosol, with implications for climate and human health. The recent EU Directive 2024/2881 highlights the need to monitor emerging pollutants like black carbon more effectively. This study presents an brief field campaign at an urban background site aimed at characterizing carbonaceous aerosols. Daily samples of PM₁₀ and PM_2.5 were analyzed using a Sunset thermal-optical analyzer to determine organic and elemental carbon (OC, EC), while real-time equivalent black carbon (eBC) was measured with three independent instruments: MAAP, AE33, and Giano BC1. Total carbon (TC) was monitored using an online TCA08 thermo-catalytic analyzer. The average concentration of PM₁₀ was 17.1 µg/m³ and 10.4 µg/m³ for PM_2.5. On average, OC and EC represented 16.5% and 3.6% of PM₁₀ mass, and 22.6% and 5.5% of PM_2.5. SOC accounted for 36% of OC. The in situ Mass Absorption Cross-section (MAC), recalculated for the ECO site, was between 8.0 and 12.2 m²/g. eBC concentrations were modulated by the daily evolution of the planetary boundary-layer height and combustion sources. The apportionment of eBC was 65% from fossil fuel and 35% from biomass burning. Biomass-burning emissions were further confirmed by optical measurements, with BrC contributing 35% of absorption at 370 nm. Full article

Ammonia fuel is expected to emerge as an effective alternative to fossil fuels due to its zero-carbon nature, high-efficiency storage and transportation advantages, and extensive industrial manufacturing infrastructure. This study discussed the impacts of compression ratio and injection timing on combustion and emission characteristics of an ammonia/diesel dual-fuel (ADDF) engine using numerical simulation. Results indicated that the corresponding optimal indicated thermal efficiency (ITE) continuously increases with an increasing compression ratio. When the compression ratio is 15:1, the injection timing corresponding to the maximum indicated thermal efficiency is −18 °CA after top dead center (ATDC). When the compression ratio ranged from 16:1 to 19:1, the corresponding optimal ITE was achieved at a retarded injection timing of −12 °CA ATDC. At a compression ratio of 19:1, the optimal ITE reached 47.9%. The in-cylinder formation regions of nitrous oxide (N₂O) are closely correlated with NH₃, NO, and temperature distributions, being primarily located at the interface between high-concentration regions of unburned NH₃ and NO. Under the comprehensive impact of increased compression ratio and advanced injection timing, both N₂O and unburned NH₃ emissions show a tendency of increasing first and then decreasing, while NO_x emissions demonstrated a monotonically increasing behavior. Full article

In this study, Copernicus Atmosphere Monitoring Service (CAMS) reanalysis data (EAC4 & EGG4) are used. To capture short-term variations and analyze long-term changes in CO₂ and CH₄, this study focuses on two specific regions of interest in each of three European countries: Greece, Italy, and France. Both CO₂ and CH₄ exhibit a positive trend with seasonally averaged increases of over 6% and 2%, respectively, compared to the reference period 2003–2013. Enhanced CH₄ concentrations in Greece are observed during winter, primarily linked to anthropogenic sources such as fossil fuel combustion, heating, industrial activities, and gas distribution. Additionally, positive CH₄ residuals exceeding 0.6% were detected in autumn, likely due to regional agricultural activities in N. Greece and/or wildfires in Athens. Winter, spring, and autumn are the seasons during which CH₄ concentrations are typically highest in the Basilicata and Po Valley regions of Italy, primarily due to agricultural activities, waste management processes, and natural gas extraction, particularly in the Val d’Agri region. Higher CH₄ variability was found during winter in France. Regarding CO₂, all countries show a large diurnal variability (approximately ± 2 ppm), that of a typical mid-northern-hemisphere site, largely associated with the biospheric cycle of photosynthesis and enhanced by anthropogenic emissions and wildfire episodes. Full article

In recent decades, pollutant emissions from the combustion of fossil fuels have become increasingly serious for the environment. The present paper reports experimental results for research carried out under laboratory conditions for a Selective Catalytic Reduction (SCR) system, implemented in different configurations on an ISUZU 4JB1 diesel engine. The obtained results allow for a comparative analysis of NOx formation as a function of diesel engine load (χ = 25–100%), at 1350, 2100, 2850, and 3600 rpm, with the engine operating under either cold (T < 343 K) or warm (T > 343 K) regimes. A preheating system for AdBlue droplets, in the form of a metal honeycomb that uses electromagnetic induction and incorporates a high-frequency generator, was introduced in the flow path of the combustion gases and tested to compare the experimental results. This system enabled temperatures of up to 643 K. A magneto-strictive system was also introduced in the SCR structure to atomize the AdBlue droplets to a minimum diameter of 3.5 μm. Using this principle, combined with preheating, the effect of calefaction was compared with the classical case of the internal heating of the SCR catalyst. For experimental purposes, piezoelectric cells dedicated to the transformation of the AdBlue solution into micro- or nano-droplets, which were entrained into the SCR by an ejector, were also used. Experimental results are presented in graphical form and reveal that the use of preheating, heating, or piezoelectric cells leads to improved NOx conversion. The tested solutions showed reductions in NOx emissions of up to eight times depending on the diesel engine load, demonstrating their strong impact on NOx reduction. Full article