Search Results (640)

One of the most promising mid-term solutions for reducing GHG emissions from the aviation sector is alternative aviation fuels, especially sustainable aviation fuels (SAFs). Regulations imposed by the Fit for 55 package to use 38% of SAFs until 2050 require a comprehensive analysis of SAFs and production pathway development with increased blending limits of alternative fuel. Within this review, a summary of key aspects of alternative aviation fuels is presented. The review contains a description of the certification process and certified production pathways with an analysis of feedstocks used for SAF production. SAF emissions also have been analyzed based on available research. SAFs reduce particulate matter emissions significantly, even by 70%, compared to fossil fuels. The emission of gaseous exhaust compounds, such as carbon monoxide, unburned hydrocarbons and nitrogen oxides, also is discussed. Alternative aviation fuels have a lower LCA compared to conventional aviation fuel and the LCAs of specific feedstocks are presented. Full article

This article compares the emission of gaseous pollutants such as CO₂, CO, NO, SO₂, and HCl emissions from the combustion of the selected most popular solid fuels in a low-power boiler. The process was carried out under controlled conditions on a laboratory stand equipped with a Moderator Unica Vento Eko 25 kW boiler. Solid fuels were selected for comparison, such as hard coal with granulation above 60 mm, hard coal with a granulation of 25–80 mm, hard coal with a granulation of 8–25 mm, wood pellets, and mixed firewood. The experiment was carried out in two stages. In stage 1, previously selected solid fuels were combusted under controlled repeatable conditions, while simultaneously measuring gaseous components in the exhaust gases in real time. On the other hand, the second stage involves the combustion of the same fuels under the same conditions with combustion additives that modify the combustion process in terms of reducing the emission of pollutants. At the same time, in the second stage, gaseous components in the exhaust gas were also measured in real time. The experiments carried out have shown that, in addition to the additive, a testing system should be used to assess the profitability and improve the efficiency of energy production and distribution after using a given additive for fuel combustion. Implementation of the use of solid fuel activators on a common scale should also entail research on the emission of dioxins and furans, which may be emitted in increased amounts under the influence of some components contained in combustion modifiers. Full article

Providing electrical power to ships while they are docked, cold ironing allows ships to turn off their engines and reduces emissions of air pollutants and greenhouse gases. This study identifies and assesses ship and port emissions and analyzes the potential for emission reduction achievable by cold ironing in European ports. It includes (1) a review of the current state of cold ironing in European ports; (2) an analysis of the time spent in ports by ships; (3) a quantification of emissions potentially avoided by means of a larger-scale use of cold ironing in Europe; (4) an estimation of the benefits achievable and the perspective to play a role in meeting emission reduction targets, improving air quality in port cities; (5) an analysis of the challenges and limitations of larger-scale cold ironing implementation; (6) potential solutions to overcome them. The results of this study could have important implications for (a) the shipping industry, which could benefit from the need for additional standardized electrical equipment onboard; (b) port authorities, which could benefit from providing additional services to the ships; (c) policymakers working to reduce emissions and promote energy efficiency, who could better approach their local and global targets. Full article

Nitrate leaching, greenhouse gas emissions, and water loss are caused by conventional water and fertilizer management in vegetable fields. The Expert-N system is a useful tool for recommending the optimal nitrogen (N) fertilizer for vegetable cultivation. To clarify the fates of water and N in vegetable fields, an open-field vegetable cultivation experiment was conducted in Dongbeiwang, Beijing. This experiment tested two irrigation treatments (W1: conventional and W2: optimal) and three fertilizer treatments (N1: conventional, N2: optimal N rate by Expert-N system, and N3: 80% optimal N rate) on cauliflower (Brassica oleracea L.), amaranth (Amaranthus tricolor L.), and spinach (Spinacia oleracea L.). The EU-Rotate_N model was used to simulate the fates of water and N in the soil. The results indicated that the yields of amaranth and spinach showed no significant differences among all the treatments in 2000 and 2001. However, cauliflower yield under the W1N2 and W1N3 treatments obviously reduced in 2001. Compared with the W1 treatment, W2 reduced irrigation amount by 27.9–29.8%, water drainage by over 76%, increased water use efficiency by 5–17%, and irrigation water use efficiency by 29–45%. Nitrate leaching was one of the main pathways in this study, accounting for 8.4% of the total N input; compared to N1, the input of fertilizer N under the N2 and N3 treatments decreased by over 66.5%, consequently reducing gaseous N by 48–72% and increasing nitrogen use efficiency (NUE) by 17–37%. Additionally, compared with the W1 treatments, gaseous N loss under the W2 treatments was reduced by 18–26% and annual average NUEs increased by 22–29%. The highest annual average NUEs were under W2N3 (169.6 kg kg⁻¹) in 2000 and W2N2 (188.0 kg kg⁻¹) in 2001, respectively. We found that optimizing fertilizer management allowed subsequent crops to utilize residual N in the soil. Therefore, we suggest that the W2N3 management should be recommended to farmers to reduce water and N loss in vegetable production systems. Full article

We show that in plasmas generated in deuterium in the presence of sputtered W surfaces, various molecular tungsten species are formed, whose chemical composition depends on the presence of gaseous impurities, namely, nitrogen, oxygen, and hydrogen. A magnetron discharge was used for plasma sustaining, and the species were investigated by mass spectrometry and optical emission spectroscopy. The identified tungsten-containing molecules are described by the chemical formula WO_xN_yD_zH_t, where x = 0–4, y = 0–3, z = 0–3, t = 0–5. Presumptively, even higher mass tungsten molecular species are present in plasma, which were not detected because of the limitation of the spectrometer measurement range to 300 amu. The presence of these molecules will likely impact the W particle balance and dust formation mechanisms in fusion plasmas. Full article

This study evaluated the suitability of two types of beech wood pellets as renewable, low-emission biofuel sources in order to combat the energy mix and poor air quality in Serbia. Key solid biofuel characteristics, including the heating values (18.5–18.7 MJ/kg), moisture content (5.54–7.16%), and volatile matter (82.4–84.4%) were assessed according to established standards. The elemental composition (mass fractions of 48.26–48.53% carbon, 6% hydrogen, 0.12–0.2% nitrogen, 0.02% sulfur, non-detected chlorine) and ash content (0.46–1.2%) demonstrated that the analyzed beech pellets met the criteria for high-quality classification, aligning with the ENplus A1 and ENplus A2 standards. The emissions of O₂, CO₂, CO, NO_x, SO₂, and TOC were quantified in the flue gas of an automatic residential pellet stove and compared with the existing literature. While combustion of the beech pellets yielded low emissions of SO₂ (6 mg/m³) and NO_x (188 mg/m³), the fluctuating CO (1456–2064 mg/m³) and TOC (26.75–61.46 mg/m³) levels were influenced by the appliance performance. These findings underscore the potential of beech wood pellets as a premium solid biofuel option for Serbian households, offering implications for both end-users and policymakers. Full article

Broiler farming is a significant source of gaseous emissions. The aim of this study was to assess the effects of different litter additives on the emission of NH₃, N₂O, CO₂, and CH₄ during broiler housing and subsequent manure storage. The gaseous emissions from the housing facilities were evaluated during one fattening cycle in environmentally controlled rooms with three different additives applied to the litter material (10% w/w aluminum sulphate or biochar and 2.50 mg m⁻² urease inhibitor), as well as a control. A storage experiment was conducted under laboratory conditions for 90 days to evaluate the influence of these three additives on gaseous losses. During broiler housing, the results indicated that NH₃ emissions were reduced significantly (40–60%) by litter additives, while global warming potential (GWP) emissions were reduced significantly (31%) by Alum. The addition of Biochar (a 58% reduction) had the same significant effect as Alum (a 60% reduction) to mitigate these losses. The re-application of Urease (a 41% reduction) may be required to reach an equal or higher reduction. During storage, NH₃ and GWP emissions were not significantly affected by the litter additives. During broiler housing and subsequent manure storage, NH₃ emissions were reduced significantly (22–41%) by litter additives, whereas GWP emissions did not decrease significantly. Globally, it can be concluded that Biochar appears to be a good alternative to Alum due to its equal effectiveness in mitigating NH₃ losses, without increasing the GWP potential in the housing and avoiding pollution swapping. Full article

As an emerging environmentally friendly fuel, biodiesel has excellent fuel properties comparable to those of petrochemical diesel. Oleic acid methyl ester, as the main component of biodiesel, has the characteristics of high cetane number and low emission rate of harmful gases. However, the comprehensive chemical conversion pathway of oleic acid methyl ester is not clear. In this paper, the reactive force field molecular dynamics simulation (ReaxFF-MD) method is used to construct a model of oleic acid methyl ester pyrolysis and combustion system. Further, the chemical conversion kinetics process at high temperatures (2500 K–3500 K) was studied, and a chemical reaction network was drawn. The research results show that the density of the system has almost no effect on the decomposition activation energy of oleic acid methyl ester, and the activation energies of its pyrolysis and combustion processes are 190.02 kJ/mol and 144.89 kJ/mol, respectively. Ethylene, water and carbon dioxide are the dominant and most accumulated products. From the specific reaction mechanism, the main pyrolysis path of oleic acid methyl ester is the breakage of the C-C bond to produce small molecule intermediates, and subsequent transformation of the ester group radical into carbon oxides. The combustion path is the evolution of long-chain alkanes into short-carbon-chain gaseous products, and these species are further burned to form stable CO₂ and H₂O. This study further discusses the microscopic combustion kinetics of biodiesel, providing a reference for the construction of biodiesel combustion models. Based on this theoretical study, the understanding of free radicals, intermediates, and products in the pyrolysis and combustion of biomass can be deepened. Full article

Particulate and gaseous emissions were studied from a large two-stroke slow-speed diesel engine equipped with an open-loop scrubber, installed on a 78,200 metric tonnes (deadweight) containership, under real operation. This paper presents the on-board emission measurements conducted upstream and downstream of the scrubber with heavy fuel oil (HFO) and ultra-low sulfur fuel oil (ULSFO). Particle emissions were examined under various dilution ratios and temperature conditions, and with two thermal treatment setups, involving a thermodenuder (TD) and a catalytic stripper (CS). Our results show a 75% SO₂ reduction downstream of the scrubber with the HFO to emission-compliant levels, while the use of the ULSFO further decreased SO₂ levels. The operation of the scrubber produced higher particle number levels compared to engine-out, attributed to the condensational growth of nanometer particle cores, salt and the formation of sulfuric acid particles in the smaller size range, induced by the scrubber. The use of a TD and a CS eliminates volatiles but can generate new particles when used in high-sulfur conditions. The results of this study contribute to the generally limited understanding of the particulate and gaseous emission performance of open-loop scrubbers in ships and could feed into emission and air quality models for estimating marine pollution impacts. Full article

Residential wood combustion (RWC) is a significant source of gaseous and particulate emissions causing adverse health and environmental effects. Several factors affect emissions, but the effects of the fuel wood species on emissions are currently not well understood. In this study, the Nordic wood species (named BirchA, BirchB, Spruce, SpruceDry, Pine and Alder) were combusted in a modern stove, and the emissions were studied. The lowest emissions were obtained from the combustion of BirchA and the highest from Spruce and Alder. The fine particle mass (PM_2.5) was mainly composed of elemental carbon (50–70% of PM_2.5), which is typical in modern appliances. The lowest PAH concentrations were measured from BirchA (total PAH 107 µg/m³) and Pine (250 µg/m³). In the ignition batch, the PAH concentration was about 4-fold (416 µg/m³). The PAHs did not correlate with other organic compounds, and thus, volatile organic compounds (VOCs) or organic carbon (OC) concentrations cannot be used as an indicator of PAH emissions. Two birch species from different origins with a similar chemical composition but different density produced partially different emission profiles. This study indicates that emission differences may be due more to the physical properties of the wood and the combustion conditions than to the wood species themselves. Full article

In this systematic review, the PRISMA method was applied to examine publications from the last two decades that have investigated the noxious gaseous emissions from dairy barns. The aim was to analyse the outcomes from literature studies estimating the quantities of polluting gases produced in dairy barns, with a specific focus on ammonia (NH₃) emissions. Various studies, among those reviewed, have used mixed effects models, mass balance approaches and dispersion methods, revealing significant variability due to different experimental protocols and environmental contexts. Key challenges include the lack of standardised measurement techniques and the limited geographical coverage of research, particularly in climatically extreme regions. This review also explores proposed methods to reduce the associated effects through mitigation strategies. Estimation of NH₃ emissions is significantly influenced by the complex interactions between several factors; including animal management practices, such as controlling animal behavioural activities; manure management, like utilising practices for floor manure removal; the type of structure housing the animals, whether it is naturally or mechanically ventilated; and environmental conditions, such as the effects of temperature, wind speed, relative humidity, and ventilation rate on NH₃ release in the barn. These influential components have been considered by researchers and targeted mitigation strategies have been identified. Despite growing attention to the issue, gaps in the scientific literature were identified and discussed, particularly regarding the analysis of mitigation strategies and their long-term impacts (i.e., environmental, economic and productivity-wise). The purpose of this review is to help improve research into sustainable agricultural practices and technological innovations, which are fundamental to reducing NH₃ emissions and improving air quality in agricultural environments. Full article

With the rapid development of science, technology, and the economy of human society, the emission problem of gas pollutants is becoming more and more serious, which brings great pressure to the global ecological environment. At the same time, the natural resources that can be exploited and utilized on Earth are also showing a trend of exhaustion. As an innovative and environmentally friendly material, functionalized ionic liquids (FILs) have shown great application potential in the capture, separation, and resource utilization of gaseous pollutants. In this paper, the synthesis and characterization methods of FILs are introduced, and the application of FILs in the treatment and recycling of gaseous pollutants is discussed. The future development of FILs in this field is also anticipated, which will provide new ideas and methods for the treatment and recycling of gaseous pollutants and promote the process of environmental protection and sustainable development. Full article

Mercury (Hg) is a naturally occurring element and has been released through human activities over an extended period. The major source is the steel industry, especially sinter plants. During a sintering process, high amounts of dust and gaseous emission are produced. These gases contain high loads of SO_x and NO_X as well as toxic pollutants, such as heavy metals like Hg. These toxic pollutants are removed by adsorbing to solids, collected as by-products and deposited as hazardous waste. The by-products contain a high amount of salt, resulting in a high water solubility. In this study, to ultimately reduce the waste amount in landfills, leachates of the by-products have been produced. The dissolved Hg concentration and its distribution across different charges were determined. Hg concentrations between 3793 and 12,566 µg L⁻¹ were measured in the leachates. The objective was to lower the Hg concentration in leachates by chemical precipitation with sodium sulfide (Na₂S) or an organic sulfide followed by filtration. Both reagents precipitate Hg with removal rates of up to 99.6% for the organic sulfide and 99.9% for Na₂S, respectively. The dose of the precipitator as well as the initial Hg concentration affected the removal rate. In addition to Hg, other relevant heavy metals have to be included in the calculation of the amount of precipitator as well. Between relevant heavy metals including Hg and sulfide, the ratio should be more than 1.5. The novelty of this study is the measurement and treatment of Hg in wastewater with a high ionic strength. The high salt concentrations did not influence the efficiency of the removal methods. An adjustment of the precipitator dose for each sample is necessary, because an overdose potentially leads to the re-dissolving of Hg. It could be shown that the emission limit of 0.005 mg L⁻¹ could be reached especially by precipitation with Na₂S. Full article

Particle emissions from marine activities next to gaseous emissions have attracted increasing attention in recent years, whether in the form of black carbon for its contribution to global warming or as fine particulate matter posing a threat to human health. Coastal areas are particularly affected by this. Hence, there is a great need for shipping to explore alternative fuels that both reduce greenhouse gas emissions, as anticipated through IMO, and also have the potential to reduce particle emissions significantly. This paper presents a comparative study of the particulate emissions of two novel synthetic/biofuels (GTL and HVO), which might, in part, substitute traditionally used distillate liquid fuels (e.g., MDO). HFO particulate emissions, in combination with an EGCS, formed the baseline. The main emphasis was laid on particle concentration (PN) and particulate matter (PM) emissions, combining gravimetric and particle number measurements. Measurements were conducted on a 0.72 MW research engine at different loads (25%, 50%, and 75%). The results show that novel fuels produce slightly fewer emissions than diesel fuel. Results also exhibit a clear trend that particle formation decreases as engine load increases. The EGCS only moderately reduces particle emissions for all complaint fuels, which is related to the formation of very fine particles, especially at high engine loads. Full article

The current scientific literature predominantly focuses on pilot-scale studies concerning the effectiveness of membrane covers in reducing gas emissions during cattle manure composting. Our study centers on the application of a leading market commercial membrane cover (ePTE-TEX_comm) and a locally manufactured one (ProfiCover^®) at industrial processing levels, evaluating their efficacy in mitigating gas emission during the fifth day of the thermophilic phase. Taking into account material inhomogeneities, work environment impact, and efficiency, the results are characteristic of industrial-scale processes rarely discussed in the scientific literature. Our results, obtained with a portable gas sampler and FTIR spectroscopy measurements using corresponding standards, indicate that ePTE-TEX_comm manifested a reduction of 90.8% for NH₃ and 59.6% for CO₂. CH₄ emissions increased, suggesting their potential entrapment. N₂O and propane equivalent experienced reductions of 23.1% and 44.8%, respectively. On the other hand, ProfiCover^® presented emission reductions for NH₃ and CO₂ of 93.3% and 85.9%, respectively. CH₄, contrasting with ePTE-TEXc_omm, showed a significant reduction of 55.6%. N₂O and propane equivalent followed with reductions of 56.7% and 84.5%, respectively. All of this divergence in performance implies a potential trade-off in emission reduction efficacy between the covers. Knowledge sharing between researchers and industry partners is key to translating these technologies into widespread adoption. Full article