Emission Of Harmful Pollutants Research Articles

Evaluation of ethanol-gasoline blends in SI engines using experimental and ANN techniques

Fuel combustion has become a major global concern, with much research focusing on the various emissions resulting from different types of fuels. Due to the harmful pollutant emissions from fossil fuels, the world has turned to renewable and alternative fuels to limit toxic emissions and greenhouse effects. Ethanol is a biofuel that, when used in spark ignition engines with gasoline can improve the octane number, combustion efficiency, and produce less emissions. The current research studies the effect of different ethanol blends E0, E5, E10, and E15 with gasoline 92 on engine performance parameters and emissions of a GX35 four-stroke engine at different engine speeds. The results along the speed range reveal that increasing ethanol amount leads to an average increase of 2.7%, 1%, and 1.1% in brake power (BP), brake thermal efficiency (BTE), and CO2 emissions, respectively. Meanwhile, it causes an average decrease of 28 °C, 3%, 15 ppm, and 0.18% in exhaust gas temperature (EGT), brake-specific fuel consumption (BSFC), HC, and CO emissions respectively. Moreover, the current study develops an Artificial Neural Networks (ANN) model for predicting the performance and emissions of spark ignition (SI) engines. Python programming language is used for ANN coding to train and validate the ANN model with E15. Regression plots were generated to visualize the correlation between the target and predicted data, indicating outstanding performance. The results confirmed the model’s reliability for BP, EGT, CO, CO2, and HC parameters with R2 values more than 0.99 and with acceptable performance for BSFC and BTE with R2 of 0.9339, and 0.9708, respectively. To ensure that the is no overfitting during the ANN study, we used different statistical methods, such as validation set, cross-validation, and learning curves.

Diesel direct injection and EGR optimization for a syngas-diesel dual-fuel generator operating at constant load

Diesel generators are widely used to produce electricity and heat in remote communities. However, their use contributes to harmful pollutant and greenhouse gas (GHG) emissions, negatively impacting the environment and public health. Syngas, which is a sustainable fuel, can play an important role in the transition from petroleum to renewable fuels. When used in dual-fuel diesel engines, it can contribute to reducing GHG emissions and the cost of transporting diesel, especially for rural and remote communities. This study investigates the effects of optimising the diesel direct injection (DI) and exhaust gas recirculation (EGR) strategies on the combustion and emission performance of a syngas-diesel dual-fuel generator at constant load. The experiments were conducted using a 30-kW generator with a four-stroke, four-cylinder, turbocharged, and electronically controlled direct-injection diesel engine. The intake manifold of the engine was modified to allow introducing syngas upstream of the turbocharger. The syngas was simulated using individually controlled flow rates of hydrogen (H2), carbon monoxide (CO), carbon dioxide (CO2), and nitrogen (N2). The syngas flow rate was adjusted to replace 40% of the energy provided by diesel fuel while optimizing the diesel DI parameters such as the pilot injection timing, main injection timing and diesel direct injection rail pressure, as well as the EGR rate. The findings of this study reveal that optimizing diesel injection strategy and appropriately raising the EGR rate have a positive impact on the engine performance and emissions.

Impact of haze on potential pathogens in surface bioaerosol in urban environments

Air quality considerably affects bioaerosol dynamics within the atmosphere. Frequent haze events, with their associated alterations in bioaerosol composition, may pose potential health risks. This study investigated the microbial diversity, community structure, and factors of PM2.5 within an urban environment. We further examined the impact of haze on potentially pathogenic bacteria in bioaerosols, and analyzed the sources of haze pollution. Key findings revealed that the highest levels of microbial richness and diversity were associated with lightly polluted air conditions. While the overall bacterial community structure remained relatively consistent across different air quality levels, the relative abundance of specific bacterial taxa exhibited variations. Meteorological and environmental conditions, particularly sulfur dioxide, nitrogen dioxide, and carbon monoxide, exerted a greater influence on bacterial diversity and community structure compared to the physicochemical properties of the PM2.5 particles themselves. Notably, haze events were observed to strengthen interactions among airborne pathogens. Stable carbon isotope analysis suggested that coal combustion and automobile exhaust were likely to represent the primary source of haze during winter months. These findings indicate that adoption of clean energy alternatives such as natural gas and electricity, and the use of public transportation, is crucial to mitigate particle and harmful pollutant emissions, thereby protecting public health.

Parametric study of organic Rankine working fluids via Bayesian optimization of a preference learning ranking for a waste heat recovery system applied to a case study marine engine

This work presents an analysis of environmentally friendly organic Rankine cycle (ORC) fluids and their application in a marine waste heat recovery system (WHRS) to reduce the utilization of fuel, thus reducing the emission of harmful pollutants. The proposed WHRS consists of four subsystems: steam Rankine, organic Rankine, Seebeck effect heat to electricity conversion and desalination. Among the 80 ORC working fluids analyzed, R1233zd(E), Novec 649 and SES36 exhibit the best overall performance in terms of power output, efficiency, safety and environmental impact. The results indicate that the implementation of innovative energy efficiency systems that comply with MEPC.1-Circ.896, such as this proposal, can reduce the IMO technical energy efficiency index (EEXI) up to 7.26 % and the operational carbon intensity indicator (CII) up to 14.24 %.

State-of-the-Art and Recent Advances in the Abatement of Gaseous Pollutants from Waste-to-Energy

Despite their key role in integrated waste management, direct (incineration) and indirect (gasification/pyrolysis) waste combustion processes are still opposed by some of the general public due to the past emission levels of air pollutants. In fact, although the release of air pollutants (especially dioxin) to the atmosphere from waste combustion processes has gradually decreased over the years, thanks to the introduction of stricter regulations and more advanced removal technologies, there is still an unsolved problem regarding the public acceptance of waste-to-energy facilities. The aim of this paper is to provide an overview of the state-of-the-art air pollution control (APC) technologies used in waste combustion facilities. Air pollution control technologies are designed to reduce or eliminate the emissions of harmful pollutants into the atmosphere. These technologies are important for safeguarding public health, protecting ecosystems, complying with regulations, and promoting a more sustainable and resilient future for both local and global communities. This paper will highlight the complexity behind emission control and the efforts made by this sector over the years. This paper will also propose suggested configurations based on the interactions/complementarity between different APC technologies and recent findings to improve their performance.

Neighborhood-Level Air Pollution Monitoring and Analysis in Massachusetts

Air pollution is a significant environmental issue with far-reaching consequences for both human health and the planet. It arises from the emission of harmful pollutants, such as particulate matter, ozone, and nitrogen dioxide, into the atmosphere. These pollutants originate from various sources, including vehicles, industrial facilities, and power plants. The impacts of air pollution are wide-ranging, encompassing respiratory infections, cardiovascular disease, cancer, harm to ecosystems, and contributions to climate change. The study of air pollution is a multidisciplinary field that draws upon knowledge from physics, chemistry, biology, and engineering. Understanding the causes and effects of air pollution is crucial for developing effective strategies to mitigate its harmful effects. Physics, in particular, plays a vital role in this field by providing the tools and techniques required to measure and comprehend the behavior of pollutants. By examining air pollution, we gain insights into the factors driving this problem and can devise measures to reduce pollution levels. Moreover, this knowledge empowers individuals and societies to make informed decisions about minimizing exposure to pollutants and formulating policies and regulations that safeguard both human well-being and the environment. In our study conducted in the central Massachusetts region, we investigated the status of air pollution using a combination of Environmental Protection Agency (EPA) monitoring sites and hand-held sensors. While the EPA sites offer longterm monitoring data, hand-held devices’ flexible and affordable nature allowed us to explore air quality at the local neighborhood and street levels. By utilizing these tools, we assessed the spatial and temporal variations in air pollution within the city, aiding in the identification of localized hotspots. Such information is valuable for targeting specific areas requiring interventions and further understanding the dynamics of pollution distribution.

Numerical investigation on spray, combustion and emission characteristics of marine engine for polyol solution-heavy fuel oil blend fuels

HFO is the fuel that marine engines utilize the most frequently due to its cost-effectiveness and high energy density, but it releases many harmful pollutant emissions. With increasingly stringent regulations for marine vessels, exploring fuel optimization method for HFO to reduce pollutant emissions is essential. This study concerned the exploration of spray, combustion and emission characteristics of different polyol (ethylene glycol, glycerol, glucose) solution-HFO blends. Both CVCC spray model and marine engine combustion model were established and validated. This research indicated that introduce polyol resulted in increased evaporation mass and SPL, and reduced SMD for HFO. Polyol solution-HFO blends exhibited lower cylinder pressure, cylinder temperature and HRR compared with HFO yet were higher compared to W–HFO. In addition, polyol solution-HFO blends reduced NOX emissions, but increased HC and soot emissions compared to HFO. Conversely, increased NOx emissions and decreased HC and soot emissions for polyol solution-HFO blends compared to W–HFO. At 100 % load, NOX emissions of polyol solution-HFO blends were reduced by 1.89%–56.58 % compared with HFO, and the HC emissions and soot emissions decreased by 6.55%–50.61 % and 17.63%–60.16 % respectively, compared to W–HFO.

Performance and emission analysis of ammonia-ethanol and ammonia-methane dual-fuel combustion in a spark-ignition engine: An optical study

In light of the pressing need to address climate change, it is imperative to take immediate action to reduce conventional hydrocarbon fuel demand. In pursuit of achieving decarbonization goals, it has become apparent that modern internal combustion engines need to adopt either carbon–neutral fuels or fuels with lower hydrocarbon content. To this end, there are several options available including alternatives such as ammonia (NH3), hydrogen (H2), methane (CH4), methanol (CH3OH), and ethanol (C2H5OH). These fuels offer the potential to be produced in a manner that is either carbon–neutral (the latter two) or entirely free of carbon emissions (the former two), making them an ideal choice for powering advanced IC engines with minimum climate impact. The use of ammonia as a fuel has the potential to significantly reduce the demand for conventional fuels and decrease the emission of harmful pollutants like CO, CO2, particulates, and unburned hydrocarbons during combustion. However, as a combustion fuel, it poses several challenges, including a low burning velocity, narrow flammability range, and instabilities arising during the combustion process. This study compared the two different dual fuel approaches, mixing ammonia-ethanol and ammonia-methane, and investigated their effect on engine performance and emissions. The experiments were conducted on a light-duty, single-cylinder, and spark-ignition four-stroke engine with an optically accessible cylinder head equipped with a port-fuel injection system. The results show that blending ethanol and methane with ammonia significantly improves its combustion characteristics due to the higher flame speed of the added components. Ammonia-ethanol blends produced reduced combustion duration, lower combustion instability, and higher engine efficiency compared to ammonia-methane blends due to the higher flame speed of ethanol. Additionally, ammonia-ethanol blends also produced higher NOx and CO2 emissions due to the higher in-cylinder temperature and lower H/C ratio. The study also applied high-speed natural flame luminosity imaging to observe the flame propagation speed for various fuel blending cases. The results found that ammonia-ethanol blends produced higher flame propagation speed than ammonia-methane blends.

Waste motor engine oil – the influence in warm mix asphalt

Employing Hot Mix Asphalt (HMA) technology for asphalt pavement construction results in the emission of greenhouse gases and other harmful pollutants, contributing to significant air pollution due to extensive energy consumption. Consequently, the adoption of Warm Mix Asphalt (WMA) is recommended, given its potential for enhanced energy efficiency and reduced emissions due to lower mixing and production temperatures compared to HMA. This research delves into the impact of incorporating waste motor engine oil (WMEO) as a bitumen modifier in warm mix asphalt. The investigation involved adding WMEO at various percentages, specifically 0%, 3%, 4%, and 5% based on the weight of bitumen. The study assessed the performance of the samples in terms of penetration, softening point, stability, flow, and stiffness. The findings revealed that the incorporation of WMEO in warm mix asphalt led to a substantial improvement in penetration and softening point. Moreover, the results indicated that incorporating WMEO as a bitumen modifier could enhance the performance of WMA in terms of stability, flow, and stiffness.

Enhancing Gas Turbine Power Plant Performance in Tropical Climates by Using Inlet Air Cooling with Desiccant Dehumidification and Evaporative Cooling

Abstract Gas turbine power plants play a crucial role in meeting the growing demand for electrical energy. However, their performance can be hindered by high ambient temperatures and humidity levels in tropical climates, leading to a drop in power output. This study investigates the potential benefits of using inlet air cooling with desiccant dehumidification and evaporative cooling to improve the performance of gas turbine power plants in tropical regions. The results show that this inlet air cooling method, integrating evaporative cooling, desiccant wheel, and Maisotsenko cooler, is a viable alternative for mitigating the performance decrease of gas turbines in hot tropical conditions. Furthermore, the compressor inlet temperature can be reduced on average by 11.5 °C by using turbine exhaust gases to heat the regeneration air utilized in the desiccant wheel for dehumidification. Additionally, the power requirement of the inlet air cooling system amounts to around 0.9 MW compared with an improvement of more than 2 MW in power output at peak temperature. Further research is needed to understand and quantify other benefits related to inlet air cooling, such as reducing emissions of harmful pollutants and operating at higher turbine inlet temperatures.

ENHANCED DIAGNOSTIC TECHNIQUES FOR MARINE DIESEL ENGINES: ACHIEVING IMO DECARBONIZATION COMPLIANCE

This paper discusses hardware-based methods for monitoring the operational parameters of marine diesel engines and online mathematical modeling techniques (digital twins) for calculating the emissions of CO2, NOx, soot, and other harmful pollutants. It is demonstrated that measuring and analyzing the engine's vibrational diagrams in parallel with gas pressure diagrams in the cylinders allows the evaluation of the actual fuel injection and gas distribution timings. The obtained data is used to refine the mathematical model of the engine's working process, which determines the engine's indicator parameters and power, as well as the emission of harmful substances that need to be monitored in compliance with current IMO requirements. The authors have accumulated experience in using the discussed hardware-based methods for diagnosing marine engines during operation. The hardware and software methods discussed have been implemented into a real-time system for in-service diagnostics of marine engines. The system is designed based on a modern dual-core controller with high performance and low power consumption, incorporating a high-speed ADC with sufficient capability to monitor the working process with a 0.1-degree crankshaft rotation resolution for all types of marine main and auxiliary engines. The system also utilizes wireless data transmission technology. A contemporary Android/iOS smartphone or tablet serves as the computational and graphical component of the system. This real-time system enables the utilization of all the advantages of parallel pressure and vibroacoustic analysis, including real-time determination of key operating parameters, identification of top dead center position, and evaluation of fuel delivery and gas distribution phases. Additionally, it harnesses the benefits of employing a digital twin—an online mathematical model of the engine cylinder's working process. These solutions will enhance diagnostic quality and, ultimately, improve the operational efficiency of marine engines by reducing operational costs and extending the period of reliable, trouble-free operation.

Development and assessment of a novel natural gas fuelled HCCI engine based combined power, heating, and refrigeration system

Internal combustion engines waste a significant amount of energy from the fuel they consume, mostly through the atmospheric release of engine exhaust gases. This phenomenon is well acknowledged as a significant contributor to engine inefficiencies and the production of harmful pollutant emissions. In order to tackle this issue, a bottoming cycle that combines a supercritical CO2 (S–CO2) power cycle with an ejector refrigeration cycle (ERC) is implemented. The goal is to generate power, heating, and cooling utilizing waste heat from a natural gas-powered homogeneous charge compression ignition (HCCI) engine. The study found that the HCCI engine, when not utilizing a bottoming cycle, demonstrated thermal and exergy efficiencies of 48.30% and 40.83%, respectively. However, the incorporation of S–CO2 and ERC cycles resulted in significantly higher system efficiencies of 64.90% and 48.84%, respectively. Furthermore, the proposed system has thermal efficiencies of 53.86% for electrical output, 7.801% for heating output, and 3.239% for cooling output. In addition, the HCCI engine accounts for the most exergy destruction in the system, accounting for 92.83 kW (25.72%), with losses due to in-cylinder heat transfer and system exhaust accounting for 20.63 kW (5.72%) and 12.52 kW (3.47%), respectively.

Future pathways for decarbonization and energy efficiency of ports: Modelling and optimization as sustainable energy hubs

The increasing energy demand in harbour areas, coupled with the need to reduce pollutant emissions, has led to the development of renewable energy-based polygeneration systems to face the carbon footprint of ports and ships at berth. In this way, in the coming years, ports can be converted into modern energy hubs.From this point of view, this paper presents a new dynamic simulation model for assessing and optimizing the energy and economic impact of ports. Here, energy systems and renewable sources can be designed to be connected to national electricity and natural gas grids and can include also alternative fuels (hydrogen, biomethane, etc.) and thermal energy networks, as well as different biomass fluxes (to be exploited for energy aims). Energy availability/demands of near towns and port buildings/infrastructures, as well as on-shore power supply are also included in the dynamic assessments. Hourly weather data and different prices for all the considered energy carriers are taken into account hour by hour. A multi-objective optimization approach is also implemented in the model considering energy and economic indexes to be optimized. The whole model is implemented in a computer tool written in MATLAB.For showing the capability of the developed model, a novel case study referred to the port of Naples (South-Italy) is presented. Here, several renewable energy sources are considered, including an anaerobic biodigester for producing biogas from the organic waste of docked cruise ships. A combined heat and power system (fed by biogas) is implemented in the port energy hub also for supplying absorption chillers. PV panels, and marine power generators are also included. In the conducted analysis, optimization targets are the maximization of system self-consumption and self-sufficiency as well as the minimum simple payback period. The proposed system can effectively contribute to the decarbonization of the port energy demand and reduce harmful pollutant emissions. Results showed that very high rate of renewable energy produced on-site can be exploited (up to 84%) by the considered port facilities, ensuring increasing independency from utility power grid (self-sufficiency index up to 40%). By the obtained results and through the developed simulation/optimization tool, novel design and operating criteria can be achieved for future port energy hubs featured by renewables and bi-directional energy exchange between ships and port.

Comprehensive energy footprint benchmarking of commercial electrified powertrains

This work presents a comprehensive energy management framework applied to electrified commercial powertrains with in-depth energy footprint analysis. We use our recently proposed algorithm, validated real-world powertrain system models, and Pareto-optimal analysis to optimize fuel consumption and harmful pollutant emissions. The approach involves dynamic optimization of 13 states and 4 control levers capturing complex subsystem interactions in parallel P2 and series range-extender commercial medium-duty electrified trucks. These subsystems exhibit vehicular (eco-driving), thermal, electrical, and mechanical dynamics at different time scales, and contain kinematic and combinatorial constraints, integer- and real-valued variables, interpolated look-up tables, and data maps. A Pareto-optimal solution is found by carefully optimizing fuel and NOx emissions to understand the energy footprint. Presented results exhibit rich powertrain behavior to unearth up to 6% improvement in energy demand, 2% in fuel economy and 18% in pollutant NOx reduction when compared to Dynamic Programming baseline from a coarsely modeled powertrain system. Furthermore, internal energy flow in the powertrains is analyzed to benchmark the optimal energy consumption and realize the multi-objective trade-off. Finally, a transient study problem is presented comparing cold versus warm after-treatment start conditions. It optimizes engine switching, eco-driving, and powersplit controls revealing adequate dynamic response and complex system interactions.

Inherent safety of clean fuels for maritime transport

The urgent need to reduce the emission of harmful pollutants in maritime transport promoted the development of several alternative propulsion systems based on clean fuels or carbon-neutral energy vectors. However, the alternative solutions under development pose new concerns from the safety perspective. Thus, an innovative methodology to rank the inherent safety performance of alternative systems at early design stages was developed. A case study representative of long-distance maritime transportation was analysed. The inherent safety performances of Liquefied Natural Gas (LNG), Liquid Hydrogen (LH2), and Liquid Ammonia (LNH3) were compared to that of Marine Gas Oil (MGO), assumed as a benchmark representing state-of-the-art technologies. Uncertainty and robustness of the safety ranking obtained were tested via a Monte Carlo analysis. The results show that technologies based on LNG have similar safety performances with respect to the benchmark option. Conversely, LH2 safety performance is currently limited by the lack of mature technologies for its safe storage whilst the safety of LNH3-based applications is affected by the toxicity of ammonia.

The Use of the Hierarchical Method to Group the Countries of the European Union According to their Energy and Climate Policies Adopted on the Basis of Directives of the European Parliament

Abstract Subject and purpose of work The European Union’s energy policy focuses mainly on three areas: reducing greenhouse gas emissions in the energy sector by increasing the use of RES, reducing emissions of harmful pollutants, and increasing the efficiency of the electricity used. Sustainable energy use, on the other hand, is clearly associated with an increased use of renewable energy sources, which ensures energy security, as well as diversification of energy supplies that sustain and improve the quality of the environment. The purpose of the paper is to present the diversity of the countries of the European Union in terms of the actions they take in the field of energy and climate policy resulting from the European Union directives. Materials and methods Based on the goals of energy policy presented in the EU directives a number of indicators were selected in order to describe the actions taken by EU member states. After a substantive and statistical verification, 6 variables were left. The use of the Ward’s method made it possible to create groups of countries that are similar in terms of their energy and climate policies. Conclusions The most favorable situation in terms of the effects of the climate and energy policy can be observed in the current leaders, that is in Sweden and Finland as well as in Estonia. Central European countries, mainly Poland, have high-emission economies, accompanied by low investment in modern environmentally friendly technologies. This is manifested, among others, in high concentrations of particulate matter, which contributes to poor air quality, categories in which Poland has some of the worst results in the entire EU.

Ensuring economic security of thermal power plants with accelerated decarbonization of the energy industry

The article highlights the results of a detailed study of the Report of the Institute of Economics and Forecasting of the National Academy of Sciences of Ukraine “Economically justified approach to the introduction of the National Emission Reduction Plan in Ukraine based on the experience of reducing emissions of harmful pollutants into the air by large combustion plants in Europe” and considers the European experience of state support thermal power plants/ thermal power plants. It was emphasized that among the mechanisms that were used and continue to be used to support coal generation, the most significant in terms of funding are the transitional payment mechanism, which is currently used in Poland, Germany, Portugal, the Czech Republic, Greece, Italy, and contracts for difference, which are still used in Austria, Denmark, the Netherlands, Great Britain, etc. countries It is justified that for Ukraine it is more expedient to finance reconstruction/modernization/technical re-equipment projects using the transitional payment mechanism, for which the transitional payment before payment will be calculated: for household consumers – as the product of the corresponding rate of transitional payment for final household consumers (UAH/month) and the number of household consumers connected to the network of this distribution system operator; for non-household consumers – as the product of the corresponding transitional payment rate (UAH/kWh) and the amount of electricity consumed by final non-household consumers. The inclusion in this way of a transitional payment to electricity supply tariffs (which include the cost of purchasing electricity on the market, the cost of services for its distribution and transmission, as well as the cost of the services of the electricity supplier) will not have a significant impact on their growth for both domestic and non-domestic consumers, instead, it will allow to have additional revenues, which the thermal power station/ thermal power plant will be able to direct to finance projects for their reconstruction/modernization/technical re-equipment. The introduction of transitional payment can definitely serve as only one of the alternative options for financing the implementation of projects for the modernization of thermal power plants/thermal power plants and, accordingly, ensuring their economic security, but it does not finally resolve the issue of financial support for the implementation of projects for the reconstruction/modernization/re-equipment of thermal power plants, which are provided for by the National Reduction Plan emissions from large combustion plants.

Differentiation of climate and energy policy in the countries of the European Union

Purpose: The energy policy of the European Union focuses mainly on three areas: renewable energy, reducing the emission of harmful pollutants, in particular CO2, and increasing the efficiency of electricity used. Sustainable energy management, in turn, is undoubtedly associated with the increased use of renewable energy sources ensuring energy security as well as the diversification of energy supplies that support and improve the quality of the environment. The aim of the article is to present the diversity of the European Union countries in terms of actions taken in the field of energy policy resulting from climate and energy goals. Design/methodology/approach: On the basis of the objectives of the energy policy presented in the EU directives, indicators describing the activities of the Member States in this respect were selected. Then, they were subjected to substantive and statistical verification, leaving 6 variables. The tool of Multidimensional Statistical Analysis, which is a synthetic measure, was used to develop a synthetic measure of the level of achievement of the goals of the climate and energy policy. Two types of analyses were used: static for international comparisons between the European Union countries, conducted for 2021, and dynamic, for the years 2011-2021. Findings: The most favourable situation in terms of activities aimed at reducing emissions of harmful substances and improving the energy efficiency of countries can be observed in the hitherto leaders of Sweden and Finland. Together with Denmark, these countries have set very ambitious national targets for achieving a share of at least 50% from renewable energy in gross final energy consumption. All countries have increased their energy productivity index. Bulgaria, Italy and Slovakia have made the greatest reductions in pollutant emissions. In the interests of energy independence, countries are trying to increase energy production from domestic resources. The greatest improvements in this field were made in Ireland, Latvia, Portugal and Finland. The division into three groups of countries implementing the energy and climate policy introduced by the EU showed that the indicators that differentiate countries to the greatest extent, among the group of selected variables, are greenhouse gas emissions and the energy dependency ratio. Keywords: energy and climate policy, EU countries, synthetic measure. Category of the paper: Research paper.

Effect of amide-functionalized carbon nanotubes as commercial diesel and palm-oil biodiesel additives on the ignition delay: A study on droplet scale

The wide use of diesel in transport and industry demands actions to reduce the emissions of harmful pollutants in the scenario of the energy transition to renewable energy, which is currently the trend in most countries around the world. Carbon nanomaterials added to diesel have been identified as a promising alternative for reducing particulate matter and NOx emissions. However, the stability of the dispersions of these nanomaterials in liquid fuels is an issue of major concern because it determines the applicability of nanofuels to internal combustion engines. That is why some alternatives, like carbon nanomaterial functionalization, have been explored to increase the stability of nanofuels, but the addition of these functionalized nanomaterials could have an effect on the combustion properties of the blends. This work explores for the first time the effect of using amide-functionalized carbon nanotubes on the ignition delay of blends of these nanomaterials (50 and 100 ppm) and Colombian commercial diesel (90 % petroleum diesel and 10 % palm-oil biodiesel) and palm-oil biodiesel. The characterization of the ignition delay was conducted on a droplet scale through the shadowgraph technique since this property is an indicator of the performance of real compression ignition engines in terms of combustion efficiency and pollutant emissions. Results showed that the addition of carbon nanotubes, either functionalized or not, increased the volumetric expansion of the droplets before ignition by up to 1.6 % in comparison with the raw fuels. Also, the addition of carbon nanotubes reduced the ignition delay of the blends in comparison to the raw fuels by about 18.3 % and 13.1 % for biodiesel with functionalized carbon nanotubes at 50 ppm and 100 ppm, respectively; 9.4 % and 11.8 % for biodiesel with no-functionalized carbon nanotubes at 50 ppm and 100 ppm, respectively; 12.3 % and 18.3 % for commercial diesel with functionalized carbon nanotubes at 50 ppm and 100 ppm, respectively; and 14.9 % and 14.7 % for commercial diesel with no-functionalized carbon nanotubes at 50 ppm and 100 ppm, respectively. However, the reduction for biodiesel with functionalized carbon nanotubes at 100 ppm was not significantly different from that of the biodiesel added with no-functionalized carbon nanotubes at 50 and 100 ppm. In the case of commercial diesel, despite the reduction of the ignition delay for all the nanofuels in comparison with the raw fuel, there was not a significant difference between the functionalized and no-functionalized blends.

Prenatal Exposure to Ambient PM2.5 and Early Childhood Growth Impairment Risk in East Africa.

Height for age is an important and widely used population-level indicator of children's health. Morbidity trends show that stunting in young children is a significant public health concern. Recent studies point to environmental factors as an understudied area of child growth failure in Africa. Data on child measurements of height-for-age and confounders were obtained from fifteen waves of the Demographic and Health Surveys (DHS) for six countries in East Africa. Monthly ambient PM2.5 concentration data was retrieved from the Atmospheric Composition Analysis Group (ACAG) global surface PM2.5 estimates and spatially integrated with DHS data. Generalized additive models with linear and logistic regression were used to estimate the exposure-response relationship between prenatal PM2.5 and height-for-age and stunting among children under five in East Africa (EA). Fully adjusted models showed that for each 10 µg/m3 increase in PM2.5 concentration there is a 0.069 (CI: 0.097, 0.041) standard deviation decrease in height-for-age and 9% higher odds of being stunted. Our study identified ambient PM2.5 as an environmental risk factor for lower height-for-age among young children in EA. This underscores the need to address emissions of harmful air pollutants in EA as adverse health effects are attributable to ambient PM2.5 air pollution.