Search Results (902)

The Leibstadt Nuclear Power Plant (KKL) recently completed a comprehensive full-scope Fire Probabilistic Safety Assessment (Fire PSA) to fulfill the updated Swiss regulatory requirements (ENSI-A05) and align with international standards. The study was conducted using the NUREG/CR-6850 framework, incorporating state-of-the-art methodologies across different areas of the study, advanced fire modeling tools (CFAST and FDS), and the latest plant-specific data. As part of detailed fire modeling, a bespoke methodology was developed, tailored to KKL’s plant-specific characteristics, to ensure a systematic and standardized approach to fire scenario analysis while maintaining quality, consistency, and traceability. The analysis focused on evaluating fire risks in critical plant areas, such as the drywell, containment, main control room, remote shutdown areas, and cable spreading room. For each scenario, the fire-generated conditions, such as the extent of fire propagation and the time to damage targets, were analyzed using plant-specific heat release rate (HRR) and calorific potential (CALPOT) values. The study also addressed aspects such as multi-compartment analysis, fire-induced cable impacts, and treatment of multiple spurious operations. This paper highlights the methodological enhancements achieved by integrating international best practices and KKL-specific adaptations into a unified fire modeling framework. The results provide critical insights into fire propagation dynamics, validate the effectiveness of safety features, and support risk-informed decision-making for enhanced fire safety and regulatory compliance. The outcomes of fire modeling were utilized to develop fire event trees and refine the consequences of fire scenarios, thereby enabling a more realistic estimation of fire risk in the KKL Fire PSA study. Overall, the KKL PSA aims to serve as a benchmark for future fire risk assessments in the nuclear industry. Full article

Coal preparation plants pursue maximum economic benefit, yet product structure optimization under fluctuating coal quality and changing market demand is a coupled decision-making problem involving the organization of primary products such as lump clean coal, clean coal, raw fine coal, coal slime, and gangue, together with commercial coal blending and process-scheme selection. Conventional optimization methods that focus on a single stage are often insufficient to address such complex coordinated decisions. To this end, a GPSOM–WOA nested optimization model was developed to achieve the coordinated optimization of primary product separation, commercial coal blending, and process-scheme selection under the objective of economic benefit maximization. In the outer layer, where process-scheme selection and primary product structure adjustment involve both discrete decisions and continuous variables, a simplified Group-based Particle Swarm Optimization with Multiple Strategies (GPSOM) was employed to search the primary product structure parameters and generate engineering-feasible primary product balance tables. In the inner layer, where the commercial coal blending problem is subject to multiple constraints, including ash content, moisture, calorific value, and supply demand, the Whale Optimization Algorithm (WOA) was adopted to optimize blending ratios within a restricted feasible region. A piecewise penalty function was introduced for quality-limit violations to support profit-oriented constrained optimization. Subject to commercial coal quality constraints on ash content, moisture, and calorific value, a case study of a coal preparation plant in Inner Mongolia was conducted to compare product structures and economic benefits under different process conditions. The results show that the proposed model can realize the joint optimization of primary product structure and commercial coal blending, and can provide a quantitative basis for product structure optimization and process selection in coal preparation plants. Full article

The growing demand for sustainable, decentralized energy solutions has heightened interest in biomass-based technologies for rural applications. In Mexico, the expansion of oil palm cultivation in humid tropical regions has generated large quantities of agro-industrial residues that remain largely underutilized. This review analyzes the potential of oil palm residues as feedstock for small-scale thermochemical conversion, with a particular focus on gasifier stove technologies. Key residues, including empty fruit bunches, mesocarp fiber, and palm kernel shells, exhibit favorable physicochemical properties, including adequate calorific values and high volatile matter content, which support their suitability for gasification processes. However, challenges related to moisture content, ash composition, and tar formation may affect system performance and require appropriate pre-treatment and operational control. Gasifier stoves, especially fixed-bed and top-lit updraft (TLUD) configurations, represent a viable solution for decentralized energy generation in rural settings, improving combustion efficiency and reducing emissions compared to traditional biomass use. Despite their potential, current bioenergy policies in Mexico remain primarily focused on large-scale biofuel production, limiting the deployment of small-scale technologies. Overall, oil palm residues constitute a promising feedstock for gasifier stove applications, although their successful implementation depends on feedstock optimization, appropriate stove design, and the development of policy frameworks that support decentralized bioenergy systems. Full article

The dynamic growth of global maize production results in the generation of large amounts of residues originating from both cultivation and processing, creating a need to develop efficient and sustainable management pathways. The aim of this study was to evaluate the feasibility of utilizing selected maize-derived residues (straw, cobs, technical maize, and post-fermentation DDGS) for the production of densified solid fuels based on biochar obtained through pyrolysis at 500 °C. The study included analyses of the mineral composition of biomass and biochar, determination of biochar yield, ash content, and higher heating value (HHV). The biochar yield ranged from 30.19% to 42.49%, with the highest values obtained for DDGS (dried distillers grains with solubles). The pyrolysis process led to an increase in HHV to 25.3–32.14 MJ/kg. These values are comparable to the calorific values of hard coal. The results indicate that biochar derived from maize residues may represent a promising feedstock for the production of solid fuels with increased energy density, while the ashes generated during their combustion show potential for agricultural applications. Full article

Indonesia, particularly Central Java, generates substantial amounts of agricultural biomass residues, including melinjo shells, tobacco stalks, and cacao shells, which remain underutilized for energy applications. This study addresses the limited scientific evidence on the fuel properties and environmental performance of these residues by systematically evaluating their suitability as briquette feedstocks. A factorial experimental design was applied using three biomass types and two binders (tapioca starch and clay). The produced briquettes were characterized for moisture content, ash content, volatile matter, and higher heating value according to the Indonesian National Standard (SNI 01-6235-2000), and their environmental performance was assessed using a Life Cycle Assessment (LCA) approach to estimate associated environmental costs. The results indicate that briquettes made from melinjo shells with tapioca starch binder exhibited the most favorable performance, achieving a moisture content of 7.01%, ash content of 13.58%, volatile matter of 47.15%, and a calorific value of 5453.43 cal g⁻¹. However, the ash and volatile matter contents exceeded the recommended limits for solid biofuels. These findings demonstrate that melinjo shells are a promising feedstock for briquette production due to their relatively high energy content, while further improvements in carbonization conditions and reductions in binder proportion are required to enhance fuel quality and environmental performance. Full article

The improper disposal of end-of-life tires poses significant environmental challenges due to their petroleum-based composition and slow degradation, while simultaneously representing an underutilized energy resource. This study investigates the slow pyrolysis of shredded waste tires in a fixed-bed electrically heated reactor to evaluate the production and fuel properties of gaseous, liquid, and solid fractions. Experiments were conducted with 100 g samples under nitrogen at final temperatures of 400, 500, and 600 °C, with residence times of 40, 25, and 10 min, respectively. Higher temperatures promoted gas formation, increasing yields from 27% to 32% and achieving a maximum lower heating value of 30.54 MJ m⁻³ at 600 °C, with enhanced H₂ and CH₄ contents. Solid yields decreased slightly (41% to 37%), while char maintained stable heating values (~29 MJ kg⁻¹). Liquid yields remained near 33% and showed high calorific values (~41 MJ kg⁻¹), densities of 700–770 kg m⁻³, low acidity, low ash content, and increased viscosity at higher temperatures. Energy conversion efficiency reached 74.4% at 500 °C. The integrated evaluation of all fractions under identical conditions highlights fixed-bed pyrolysis as a promising pathway for waste-tire valorization and decentralized fuel production. Full article

A total of three variants of pellets from field bean and potato waste mixtures were investigated and analyzed. Their physical, mechanical and chemical properties were examined, and the burning emissions of pellets were measured. An experimental study was performed to determine the dependence of density and compressive strength. An empirical linear regression model was developed, allowing calculation of the density and compressive strength dependence of pellets with 84–91% accuracy. The lower calorific value of the dry waste pellets was similar across all tested samples. The chemical properties of pellet ash were determined, and its suitability for use as a fertilizer was assessed. The pellet density ranged from 1269.24 kg m⁻³ (potato pellets) to 1369.89 kg m⁻³ (potato and bean MIX DC pellets). The moisture content of the pellets varied from 6.14% to 7.37%. The moisture content of the pellets increased with the proportion of potato waste meal in the mixture. The ash contains elements magnesium, iron, calcium, potassium, silicon, sodium and phosphorus. Potassium in potato pellet ash was found to have the highest concentration (60.42%), which has a direct effect on boiler slag. The share of potato waste in biofuels helps to remove soot from the chimney in the form of solid particles. It can therefore be stated that bean and potato waste can be used in the production of solid biofuels and that pellets produced with a 20% (1:4 ratio) potato waste fraction obtain the best properties. Full article

The higher heating value (HHV), sometimes referred to as the gross calorific value, is a crucial metric for determining a fuel’s primary energy potential in energy production systems. By combining extreme gradient boosting (XGBoost) with the differential evolution (DE) optimizer, an innovative machine learning-based model was created in this study to forecast the HHV (dependent variable). As input variables, the model included the constituents of the coal’s ultimate analysis: carbon (C), oxygen (O), hydrogen (H), nitrogen (N), and sulfur (S). For comparative purposes, random forest regression (RFR), M5 model tree, multivariate linear regression (MLR), and previously reported empirical correlations were also applied to the experimental dataset. The results showed that the XGBoost strategy produced the most accurate predictions. An initial XGBoost analysis was carried out to identify the relative contribution of the input variables to coal HHV prediction. In particular, for coal HHV estimates reliant on experimental samples, the XGBoost regression produced a correlation coefficient of 0.9858 and a coefficient of determination of 0.9691. The excellent agreement between observed and anticipated values shows that the DE/XGBoost-based approximation performed satisfactorily. Lastly, a synopsis of the investigation’s key conclusions is provided. Full article

Microbial oil production has gained attention as a sustainable and cost-effective alternative to conventional vegetable and fish oils. Among oleaginous microorganisms, Yarrowia lipolytica is notable for its ability to accumulate lipids exceeding 20% of its dry weight. This study aimed to evaluate semi-continuous cultivation as a strategy for sustainable microbial oil production by Y. lipolytica, while also assessing the potential utility of the spent supernatant. Three different feeding frequencies were evaluated. In the 24 h feeding regime, the maximum oil concentration reached 11.22 g/L, decreasing to 8.43 g/L by the 88th hour. In the 6–6–12 h feeding strategy, crude protein content peaked at 43.75% of dry mass at 22 h. Fatty acid profiling revealed consistently low saturated fatty acid (SFA) levels (4.93–10.30%), while unsaturated fatty acids (UFA) dominated (89.69–95.05%). Monounsaturated fatty acids (MUFA) were predominant, reaching up to 81.24%, whereas polyunsaturated fatty acids (PUFA) ranged from 20.78% to 29.98%. Oleic acid was the most abundant fatty acid across all conditions. This composition supports the potential of microbial oil from Y. lipolytica as a sustainable alternative edible lipid ingredient for human food applications, complementing conventional plant-based oils. The favorable unsaturated fatty acid profile indicates its potential suitability for incorporation into food formulations requiring nutritionally desirable lipid sources. As part of the sustainability-oriented approach of the study, the freeze-dried post-culture supernatant was also evaluated for its potential further utilization. With a calorific value of 10.43 kJ/g and significant phosphorus and potassium levels, it shows potential as a biofuel feedstock and as a biofertilizer or biostimulant. Full article

This study examines the potential of using agricultural residues for energy production in the Córdoba department of Colombia in response to the need to diversify the energy matrix and reduce inequality in energy access. The aim was to estimate and visually represent the energy potential of nine key crop residues using agricultural data from 2015 to 2018, physical-energy characterisation, and UPME and SERI models integrated into a geographic information system (GIS). A total annual generation of 2.6 million tonnes of residual biomass was identified, with Tierralta, Lorica and Montería emerging as the main generators. Although maize did not produce the largest volume of residue, it had the highest theoretical energy potential (2621 GWh/year) due to its low moisture content and high calorific value. The total theoretical energy potential of the available biomass was estimated at 4550 GWh/year, which could cover over twice the department’s electricity demand and avoid around 745 thousand tonnes of CO₂ emissions per year. This study demonstrates that the strategic use of this biomass can promote a just and sustainable energy transition and proposes a replicable model combining technical and territorial analysis to inform public policy and encourage decentralised bioenergy projects. Full article

Steam Explosion (SE) is a relatively newly developed physicochemical pretreatment method that has received increasing attention since it can effectively upgrade biomass for further utilization. During SE, biomass is first exposed to high-temperature, high-pressure steam and then rapidly depressurized. This process efficiently breaks down the lignocellulosic structure, reduces moisture content, and increases fixed carbon and calorific value. It also enhances biomass grindability and densification, making it more suitable as a renewable solid fuel. This review carefully discusses the fundamental principles of SE and its effects on particle characteristics. Then, the types of SE reactors (mainly composed of batch reactors and continuous reactors) are systematically compared, and the challenges in scaling up and commercialization are discussed. Also, the characteristics of pyrolysis or gasification of biomass pretreated by SE are described in detail. Studies indicate that SE is beneficial for the enhancement of product quality. Finally, the prospects and future challenges in the development of SE (including superheated steam explosion, reaction kinetics improvement, and heat and mass transfer intensification) are presented and discussed. Full article

As a primary associated by-product of coal mining, the comprehensive utilization of coal gangue has become a core pathway for the green transformation of the energy system and the establishment of a resource recycling system. The fully mechanized top-coal caving mining method used in China lacks a quality linkage mechanism between underground matched mining and surface coal blending, resulting in significant fluctuations in coal quality, larger volumes of gangue brought to the surface, and low utilization rates of coal washing by-products. In this paper, we propose a reverse decision-making method for whole-lifecycle coal quality control and construct an ash content tracing and regulation model to coordinate coal blending and matched mining in fully mechanized caving faces. In the coal blending stage, under the constraints of calorific value balance and cost minimization, the method transforms low-calorific-value by-products, such as middlings and fine gangue, into valuable resources. In the matched mining stage, a reverse tracking model based on the surface–underground ash content balance is proposed, grounded in material flow analysis theory. The model formulates correlation equations among face length, the low calorific value of raw coal, daily advance per cycle, and caved gangue volume. It further proposes a reverse coal quality tracing theory that links commercial coal sales targets with caving process parameters. The study clarifies the deep coordination mechanism between underground matched mining and surface coal blending. The results demonstrate that the proposed method systematically establishes a closed-loop pathway integrating underground gangue reduction at the source and surface fine gangue blending. The implementation has yielded direct economic benefits totaling RMB 65.31 million, increased commercial blended coal output by 104.5 thousand tons, and reduced gangue emissions by 258.5 thousand tons. This study provides a reference for the reduction, resource utilization, and recycling of coal gangue. Full article

The heat release rate in internal combustion engines obtained from in-cylinder pressure data is a fundamental method to analyse the combustion characteristics of engines. As the measured in-cylinder pressure is lower than the pressure in the absence of heat loss to the walls, the methodology typically leads to the apparent rate of heat release as the heat loss to the cylinder walls cannot be segregated. Heat loss can then be inferred by reference to the chemical fuel energy expected to be released by the fuel. Typically, in engine thermodynamic analysis, the lower heating value is used to determine the energy released by the fuel. However, in this article, we argue that when detailed comparison with validated combustion modelling was done, it was concluded that the higher heating value is the more appropriate calorific value. In this research, the analysis of heat release rate and its determination using the first law of thermodynamics with constant ratio of specific heats $\gamma$ and also varying $\gamma$ is discussed. It was noted that the use of the “3rd term” (term due to the $d\gamma /d\mathsf{\vartheta }$) in the heat release rate is advisable as it gives a more reasonable heat loss even in the compression stroke. Full article

Microalgae are a promising third-generation biomass resource due to their high photosynthetic efficiency, rapid growth rates, capacity to accumulate energy-rich biochemical fractions, and efficient utilisation of carbon dioxide (CO₂). In this study, the effect of illumination colour on the growth and energetic properties of Chlorella vulgaris cultivated in laboratory-scale photobioreactors was investigated. Four independent cultivation cycles were conducted under controlled conditions using a 16 h light/8 h dark photoperiod, temperatures of 20–30 °C, and aeration with air enriched with 10% CO₂. Cultures were illuminated using six light colours: plant-specific, white, green, red, blue, and ultraviolet. Biomass productivity was quantified, and the higher heating value (HHV) of the produced biomass was determined by bomb calorimetry. In addition, proximate (technical) analysis was performed for Chlorella vulgaris and compared with Chlorella pyrenoidosa, Spirulina, and Fucus vesiculosus (bladderwrack). The results showed that white illumination promoted both the highest biomass growth and the highest HHV for Chlorella vulgaris (15.08 MJ·kg⁻¹), while ultraviolet illumination had a disruptive effect, leading to the lowest growth and calorific value (11.49 MJ·kg⁻¹). Comparative analysis revealed that Chlorella pyrenoidosa exhibited the most favourable energetic properties; however, Chlorella vulgaris remains attractive for cultivation due to its robustness and broad tolerance to operating conditions. Full article

This study investigates the key performance-related fuel properties of emulsifier–diesel solutions and ethanol-in-diesel microemulsions. This work begins with the in situ polymerization of long alkyl chain-substituted glycidyl methacrylate (R-GMA) in diesel and the optional presence of a second methacrylate monomer. The resulting diesel-soluble oligomer functions as a nonionic emulsifier. Controlled amounts of ethanol are subsequently incorporated into the emulsifier–diesel solution to form a stable microemulsion, referred to as E-Diesel. This study examines how the structure of the emulsifier influences key fuel properties, including (i) ethanol–diesel miscibility, (ii) gross calorific value, (iii) Ramsbottom carbon residue (% of fuel), (iv) entrapped polycyclic aromatic hydrocarbons (PAHs), and (v) fuel lubricity. Both the hydrophilic–hydrophobic balance and the structure of the emulsifier side chains are found to significantly affect these properties. Compared with neat diesel, oligomeric emulsifiers enable the substantial dispersion of ethanol in diesel (up to 18 wt.%). The resulting fuel exhibits a gross calorific value exceeding the theoretical sum of diesel and ethanol at the same composition (a synergistic effect) and achieves an enhancement in lubricity up to 49.5% relative to neat diesel at a 5% emulsifier loading. Although the presence of emulsifiers leads to an increase in the carbon residue by up to 54.7% compared to neat diesel during controlled pyrolysis, it simultaneously reduces the PAH content in the exhaust. Overall, this study establishes fundamental correlations among microemulsion stability, combustion synergy, carbon residue formulation, and fuel lubricity, which are governed by the structure of the emulsifier. Full article