Calorific Value Research Articles

Optimasi Peningkatan Karakteristik Crude Palm Oil (CPO) sebagai Bahan Bakar Diesel

Indonesia is one of the largest palm oil-producing countries in the world, significantly contributing to global palm oil needs. The use of palm oil as fuel is generally achieved through the biodiesel manufacturing process; however, this process remains costly and thus less economical. Additionally, the primary obstacle in using crude palm oil (CPO) is its high viscosity, which can cause blockages in the fuel injector channels of diesel engines. Therefore, modifications are necessary to enhance the characteristics of CPO so that it can be used directly as diesel engine fuel. This can be achieved through heating and the addition of 2-EHN additives. This study aimed to optimize the characteristics of CPO using Response Surface Methodology (RSM) to determine the optimal combination of temperature and 2-EHN concentration. The optimal point was identified at a temperature of 50°C and a 2-EHN concentration of 2%. The results of the CPO characteristic test showed a viscosity of 4.45 CSt, a density of 0.884 g/ml, a cetane number of 56.9, and a calorific value of 9314 kcal/kg

Transesterification of biodiesel from kapok seed oil (ceiba pentandra) using a natural heterogeneous katalyst (rice husk activation)

Biodiesel as a renewable energy source can be produced by a chemical reaction between vegetable oil or animal fat and short-chain alcohol such as methanol, ethanol or buthanol and is supported by a catalyst. This process is called transesterification. From an environmental point of view, the use of biodiesel has several advantages such as reducing carbon dioxide emissions, being non-toxic and biodegradable. Kapok seed oil has potential for exploitation, particularly as a raw material for the manufacture of biofuel. Kapok seeds (Ceiba pentandra) have the potential to be used as a feedstock for biodiesel because their oil content is quite high, around 18-25% oil. The controlled combustion of rice husks produces ash containing high purity amorphous silica. Amorphous silica can be obtained from RHA (rice husk ash) when rice husk is burned at a temperature of 700°C, and it is transformed into crystalline silica when burned at a temperature above 850 °C. This silica has many applications as a filler, adsorbent, catalyst support, star gel component and source for the production of premium silicon and its compounds. The aim of the research is to determine the transisterification process of biodiesel from kapok (Ceiba pentandra) seed oil. using a natural heterogeneous catalyst in It is an activated rice husk. The method used was the preparation of kapok seed samples and the extraction of sokhlet. Determination of free fatty acids (FFA) in kapok seed oil, activation of rice husk, manufacturing of biodiesel from kapok seed with addition of rice husk H2SO4 as catalyst. The characteristics of the biodiesel produced are Density: 859.88572 kg/m3 (SNI: 7182:2015) = 850-890 kg/m3), Viscosity: 2.45824 cSt (SNI: 7182:2015) = 2.3 – 6, 0 cSt, Calorific value: 7,374.5322 cal/g (SNI: 7182; 2015) = 7,100 -11,000 cal/ g, Devil's number: 48 (ASTM: D6751) = 47. Meanwhile, GC-MS with the highest values at all reaction times, namely Hexadec anoic acid, methyl ester (C17H34O2), methyl tetradecanoate (C15H30O2) and 9 - Octadecenoic acid (Z), methyl ester (C19H36O2) . The functional group found in kapok seeds is –OH.

Energy Quality of Corn Biomass from Gasoline-Contaminated Soils Remediated with Sorbents

Soil contaminated with petroleum-derived products should be used to cultivate energy crops. One such crop is Zea mays. Therefore, a study was performed to determine the suitability of Zea mays biomass obtained from gasoline-contaminated soil for energy purposes. The analysis included determining the heat of combustion and calorific value of the biomass, as well as the content of nitrogen, carbon, hydrogen, oxygen, sulfur, and ash in the biomass. Additionally, the suitability of vermiculite, dolomite, perlite, and agrobasalt for the phytostabilization of gasoline-contaminated soil was evaluated. It was found that the application of sorbents to gasoline-contaminated soil significantly reduced the severe negative effects of this petroleum product on the growth and development of Zea mays. Gasoline contamination of the soil caused a significant increase in ash, nitrogen, and sulfur, along with a decrease in carbon and oxygen content. However, it had no negative effect on the heat of combustion or calorific value of the biomass, although it did reduce the energy production from Zea mays biomass due to a reduction in yield. An important achievement of the study is the demonstration that all the applied sorbents have a positive effect on soil stabilization, which in turn enhances the amount of Zea mays biomass harvested and the energy produced from it. The best results were observed after the application of agrobasalt, dolomite, and vermiculite on gasoline-contaminated soil. Therefore, these sorbents can be recommended for the phytostabilization of gasoline-contaminated soil intended for the cultivation of energy crops.

Optimal Conversion of Food Packaging Waste to Liquid Fuel via Nonthermal Plasma Treatment: A Model-Centric Approach.

The efficiency of employing a multifactorial approach to enhance the nonthermal plasma (NTP) chemical conversion of solid waste food packaging materials into liquid petroleum hydrocarbons was assessed for the first time in this study. The researchers adopted a hybrid approach which integrated the zero-dimensional (0-D) and response surface model (RSM) techniques. After their application, the researchers noted that these strategies significantly enhanced the model prediction owing to their accurate electrochemical description. Here, the researchers solved a set of equations to identify the optimisation dynamics. They also established experimental circumstances to determine the quantitative correlation among all process variables contributing to food plastic packaging waste degradation and the production of liquid fuels. The findings of the study indicate a good agreement between the numerical and experimental values. It was also noted that the electrical variables of NTP significantly influenced the conversion yield (Yconv%) of solid plastic packaging waste to liquid hydrocarbons. Similarly, after analysing the data, it was seen that factors like the power discharge rate (x1 ), discharge interval (x2), power frequency (x3), and power intensity (x4) could significantly affect the product yield. After optimizing the variables, the researchers observed a maximal Yconv% of approximately 86%. The findings revealed that the proposed framework could effectively scale up the plasma synergistic pyrolysis technology for obtaining the highest Yconv% of solid packaging plastic wastes to produce an aromatics-enriched oil. The researchers subsequently employed the precision of the constructed framework to upgrade the laboratory-scale procedures to industrial-scale processes, which showed more than 95% efficiency. The extracted oil showed a calorific value of 43,570.5 J/g, indicating that the liquid hydrocarbons exhibited properties similar to commercial diesel.

The Study of Post-Harvest Processing and Handling of Residues From Plants Grown Primarily For Agronomics: Soybean Stalk, Corn Stover, Tomato Vine, Cucumber, Eggplant, and Summer Squash

Information on post-harvest handling of the crop is critical to the development of new or improved plant species and traits. This paper presents a comprehensive study of the grinding characteristics and handling properties of a number of crop residues under agronomic studies. We used a laboratory-scale knife mill connected to an in-line power meter to investigate the specific energy of size reduction for each crop. The summer squash sample yielded the smallest mean particle size upon grinding (P= 0.05). The results indicate a significant correlation between the Carbon to Oxygen (C/O) ratio and the Gross Calorific Value (GCV), ash, lignin content, and net specific grinding energy consumption (NSGEC) of the samples. Among agricultural residues, the soybean stalk sample, with the highest C/O ratio (0.96), exhibited the highest GCV (17.5 MJ/kg, db) and NSGEC (31.7 kWh/t), while the summer squash sample, with the lowest C/O ratio (0.46), showed the lowest GCV (13.6 MJ/kg, db) and NSGEC (5.1 kWh/t). The flowability of the ground biomass samples varied, with cucumber showing the best free flow properties. The results also showed that there is a significant positive correlation between the lignin content and NSGEC of all samples (p= 0.05).

Catalytic hydrothermal reaction of biomass and its application in blast furnace injection: Physicochemical, conversion mechanism, combustion behavior

This study employs a combination of experimental research and computational fluid dynamics (CFD) simulation to evaluate the optimal conditions for catalytic hydrothermal carbonization suitable for blast furnace injection. Through FTIR spectroscopy, Raman spectroscopy, ICP analysis, and combustion kinetics analysis, the physical and chemical properties of the hydrochar were determined. Subsequently, these properties along with kinetic parameters were applied to an improved CFD model to compare the flow patterns and combustion performance of hydrochar with PCI coal in blast furnaces. The results indicate that the optimal HTC conditions are identified at 300 °C with FeCl3 catalysis, yielding hydrochar (HTC-300-FeCl3) characterized by a calorific value of 32.10 MJ/kg, 98 % K element removal, and enhanced carbonaceous structure ordering. This is attributed to the addition of FeCl3 effectively enhances the generation of hydroxyl radicals in the aqueous phase and promotes deoxygenation and hydrogenation reactions in the solid phase, improving the quality of hydrochars. In addition, CFD model shows that the HTC-300 FeCl3 exhibits a higher burnout (86.2 %) and average gas temperature (2383.1 K) compared to PCI coal, indicating its greater potential as a PCI coal substitute in BF injection.

Sustainable Valorisation of Coffee Waste as a Protein Source, Mycelium-Based Packaging Material and Renewable Energy Pellet.

This study investigates the valorization of spent coffee grounds (SCGs) through protein extraction and their application in mycelium-based packaging and renewable energy pellets. Three extraction methods-mechanical stirring, ultrasound-assisted, and CO2-assisted extraction-were applied to SCGs. CO2-assisted extraction yielded the highest protein content at 34.24%, followed by mechanical stirring (31.46%) and ultrasound-assisted extraction (28.51%). The total polyphenol content and antioxidant capacity were also highest in the CO2 extracts, suggesting that this method preserves bioactive compounds most effectively. After protein extraction, SCGs were tested as a component in mycelium-based packaging, with results showing an apparent density of 0.551 g/cm3 and compression resistance of 3.354 MPa, indicating its suitability for structural applications. The energy value of SCGs remained high, with a calorific value of 19,887 J/g DW, slightly decreasing after extraction but still sufficient for renewable energy production. These findings highlight the potential of SCGs as a multi-functional resource, contributing to sustainable solutions across various industries.

Quality assessment of briquettes derived from carbonized cassava peel and sawdust as sustainable domestic sources of energy in Oyo State, Nigeria

About 80% of Nigeria’s rural and semi-urban population uses fuelwood, which accounts for 37% of the country’s energy demand. This results in the annual loss of 350,000 to 400,000 hectares of forest, increased carbon emissions, and loss of biodiversity, affecting ecosystems and quality of life. Therefore, this study was conducted to evaluate the physicochemical and combustion properties of carbonized cassava peel (CP) and sawdust (SD) hybrid briquettes as an alternative to fuelwood. Factors considered were CP/SD ratios (100:0, 75:25, 50:50, 25:75, 0:100), binder concentrations (5 and 10 g), and residence times (10, 20, 30 min). The briquettes were produced by applying a low compaction pressure of 2.4 MPa. The briquettes exhibited densities of 320.00-627.79 kg/m³, moisture content of 4.37-8.22%, water resistances of 87.26-99.85%, ash content of 5.73-41.03%, calorific values of 20.01-32.30 KJ/kg, and carbon content of 55.25-57.07%, respectively. ANOVA and Duncan’s multiple range tests revealed that CP/SD ratio is the most significant factor influencing the physicochemical and combustion properties of the briquettes. This study successfully showcased carbonized CP/SD briquettes as an alternative cooking fuel in Oyo State, leveraging the abundance of CP and SD and the feasibility of low-pressure compaction without costly equipment.

Prediction and policy: Do empirical gross calorific value prediction help reduce coal testing overload?

The gross calorific value (GCV) of coal is pivotal in shaping policies across various sectors of the Indian economy. It plays a crucial role in classification and valuation of coal and is a major factor in determining electricity tariffs charged by thermal power plants. With coal production escalating year-on-year to meet India's increasing electricity demand, there is significant rise in coal testing activities along the pit-to-power supply chain at multiple points and by multiple testing agencies often driven by sector-specific policy requirements. While laboratory testing accurately determines GCV, it is costly and time-consuming due to the reliance on expensive equipment and skilled personnel. Global researchers have previously devised a plethora of empirical formulae predicting GCV based on its correlations with easy-to-measure properties like moisture and ash content. However, the applicability and utility of these formulae to the prevalent policy matrix of coal and power sector remain to be explored. The introduction of independent third-party assessment of coal quality by Coal India Limited in 2016 has generated a vast dataset of coal sample-test results, offering an opportunity to reassess existing empirical formulae, test their alignment with existing policies, and explore possibility of a unified, region-neutral formula for rapid GCV prediction with a special focus on alleviating the current overload in coal testing.

Biomass Energy from Agricultural Waste: Evaluating Groundnut Vines and Pumpkin Straws for Combustion Performance

Energy demand has risen significantly in developing countries due to rapid population growth and increase in economic activities such as industrialization, automation manufacturing and digitalization. Dependency on conventional sources of energy in both rural and peri-urban is high. Traditional energy resources lead to environmental degradation due to carbon oxide release leading global warming and deforestation which results to hydrological decline; therefore, need to come up with renewable resources from other sources such as agricultural wastes to meet the demand and solve environmental pollution problems. This study carried out an investigation on combustion and performance analysis of pumpkin straws and groundnut vines to establish their energy potential. ASTM standards were used to determine the proximate and ultimate properties. This analysis revealed moisture content (8.7-12.4%), volatile matter (63-69%), fixed carbon (11.5-18.5%), ash content (6.3-8.2%), Sulphur (0.09-0.13%), nitrogen (1.02-1.03%), oxygen (5.01-55.88%), carbon (41.8-43%) and hydrogen (5.96-6.3%). Calorific values for the briquettes were above 4389 kCal, which is above most biomass. The density and compressive strength were above 0.63 g/cm3 and 17N/mm2 respectively from compaction pressure of 150, 250 and 350 kg/cm2. The burning time was between 4 and 5.3 min, showing an increase with compaction pressure, burning rate ranged between 4.3 and 2.9 g/min, a decrease with compaction pressure increase. The specific fuel consumption portrayed an inverse relationship with calorific value and a direct relationship with compaction pressure, ranging between 166 to 176 grams per litre. Temperature-weight analysis revealed thermo stability of this feedstock, portraying resemblance to proximate analysis. Having exhibited close relationship to other agricultural wastes used for fuel, groundnut vines and pumpkin straws are a solution to environmental degradation by reducing deforestation and emissions. It is recommended that further research on mixing this feedstock with other agricultural wastes as well as making and testing of pellets be carried out to maximize energy output.

Investigations into Biomass Utilization: A Renewable Alternative Fuel for Sustainable Energy

Indian municipal solid waste production exceeds 55 million tonnes per year, with a five percent yearly growth. Municipal solid waste has several environmental benefits, making it a promising feedstock for large-scale energy production. For energy utilisation, consider pelletising municipal solid waste with or without a binder. The volume of municipal solid trash created causes deposition, degradation, and maintenance concerns. India is increasing rapidly in population and urbanisation. This has consistently increased municipal solid trash production. The Planning Commission of India reports that 51% of Indian municipal solid trash is organic. Yard debris and food waste from restaurants, hotels and retail stores make up most of it. Since one-third of food is wasted, it's a major concern. One billion and three hundred thousand tonnes of food waste are produced worldwide. Municipal trash is dumped at open dumps in India. Open dumping is the least recommended method of solid waste management because it emits greenhouse gases and produces foul odours, flies, and rats, which spread disease and cause complaints in nearby residential areas. The spilt leachate may also affect nearby ground and surface waterways. Open dumps also need land, which is scarce in densely populated India. This is a major issue in India because landfills are open dumping sites without engineering solutions. Compared to anaerobic digestion and biomass gasification, pelletisation is a better organic waste treatment. Pelletisation is easy if wastes are categorised. After separation, garbage is treated and turned into pellets for burning. This study examines sixteen samples for calorific value, moisture, ash, and CHNS ratio. Energy crops, agricultural trash, forestry waste, and municipal garbage are samples.

Production of high-calorific hybrid biofuel pellets from urban plastic waste and agro-industrial by-products

Advances in waste-to-energy technology and sustainable fuel production drive significant changes in the energy industry. These innovative solutions not only address waste management challenges but also contribute to broadening the energy source matrix and reducing dependence on traditional fossil fuels. This study evaluates the incorporation of polyethylene and polypropylene urban plastic waste in various agro-industrial by-product blends, which combine beet pulp, radiata pine, and eucalyptus bark wastes. The generation of the hybrid biofuel from agro-industrial waste and domestic solid waste in pellet form is investigated to determine the optimal blends in terms of durability, ash generation and calorific value. Both urban plastics incorporated in the mixtures not only significantly increase the calorific energy value but also promote the binding of the solid biofuel components. The polypropylene-based urban plastic pellet exhibited superior binding capacity and lower ash generation, even in complex hydroxyl functional groups. It also displayed suitable properties for solid biofuels, such as low fine content, high durability, and dimensional stability. The highest resulting calorific value of 22.6 MJ/kg was determined for the mass ratio of the blend with 99% durability, 0.23% fines content, and 5.1% combustion ash generation. This new hybrid biofuel is presented as a sustainable option and a significant contribution in the field of waste-to-energy technology and renewable energy production. The production cost of the hybrid biofuel is competitive with wood-based biofuels, with only a 6.25% increase observed for pellets made from 50% wood and 20% beet pulp compared to traditional 100% wood pellets. However, significant cost reductions were achieved through specific configurations, resulting in savings of 14.8%. The novel hybrid biofuel requires only 9.2 MJ/kg to produce 22.6 MJ/kg, demonstrating significant energy impact and viability as a sustainable energy source in waste-to-energy technology and renewable energy production.

Evaluation of Advanced Biofuels in Internal Combustion Engines: Diesel/Fusel Oil/Vegetable Oil Triple Blends

In this research work, the feasibility of using fusel oil, a by-product of the sugar–alcohol industry, as an LVLC solvent in blends with straight vegetable oils (SVOs) and diesel was investigated. Concretely, diesel/fusel oil/sunflower oil (D/FO/SO) and diesel/fusel oil/castor oil (D/FO/CO) triple blends were prepared and characterized by measuring the most important physicochemical properties, i.e., viscosity, density, cold flow properties, flash point and cetane number. An appreciable improvement in cold flow values has been achieved with triple blends, without compromising properties such as calorific value and cetane number. Likewise, the triple blends meet the viscosity and density requirements specified by the European quality standard EN 14214 and the American standard ASTM D6751. After characterization, the triple blends were used on a diesel engine, evaluating different parameters such as power output, opacity, exhaust emissions (CO and NOx) and consumption at different engine loads. The results indicate that as the biofuel content in the blend increases, engine power decreases while fuel consumption rises. Nevertheless, the values obtained with D/FO/CO are better than those for D/FO/SO and are also very similar to those of fossil diesel. Regarding opacity values and NOx emissions obtained with the utilization of the triple blends, they are lower than those produced by diesel. However, in the case of CO emissions, it depends on the type of oil used, with the samples prepared with castor oil exhibiting the best results.

Evaluation of the Feasibility and Utilizability of Pretreated Sewage Sludge in Cement Kiln Co-Processing

The treatment and resource utilization of sludge from municipal sewage treatment plants is an important environmental issue. Cement kiln co-processing offers a promising solution, but challenges remain, particularly regarding sludge properties and feasibility in kiln systems. This study analyzes the characteristics of three pretreated sludges: mechanically dewatered sludge, deeply dewatered sludge, and lime-dried sludge. Using techniques such as thermogravimetric analysis (TGA) and X-ray diffraction (XRD), this study investigates their calorific values and raw material utilizability in co-processing. As the sludge moisture content decreases from interstitial to bound water, energy consumption per ton of evaporated water rises, particularly below 30%. At 10 °C/min heating, energy consumption for mechanically dewatered sludge at 80%, 30%, and 10% moisture was 3573, 8220, and 34,751 kJ/kg, respectively; for deeply dewatered sludge at 60%, 30%, and 10%, the values were 4398, 7550, and 11,504 kJ/kg. Keeping moisture content above 30% before kiln entry reduces energy use and enhances calorific value. Sludge utilizability as a raw material depends on its pretreatment. The ash composition of deeply and mechanically dewatered sludge resembles iron-rich raw materials, while lime-dried sludge aligns more with limestone. The utilizable ash content was 23.3%, 8.1%, and 46.3%, respectively, with lime-dried sludge showing the highest potential. This study provides insights into sludge properties and their co-processing potential in cement kilns, offering scientific and technical support for practical applications.

Experimental and performance analysis of organic fraction of municipal solid waste in downdraft gasifier

It is anticipated that the production of municipal solid waste will increase from 2.10 billion tonnes in 2023 to 3.80 billion tonnes by 2050. About 170 billion metric tonnes of biomass is produced worldwide each year. On a wet basis, the composition of municipal solid waste (MSW) includes approximately 20% of wood, 70% of food waste, 60% of yard trimmings, and 50% of other organic materials. Gasification of waste biomass is one of the most efficient processes for creating gaseous fuel and subsequently power with reduced environmental impact. The current work presents a novel strategy to reduce MSW by converting waste into briquettes and feeding it in gasifiers to produce syngas. The downdraft gasifier is employed in the syngas generation process. With a calorific value of 22.6 MJ/kg and a higher lignin concentration of approximately 31%, MSW proves to be suitable for thermochemical conversion processes. This article presents the results during gasification of briquette made from organic fraction of municipal solid waste (OFMSW) with significant heating value of 22.6 MJ/kg. The fuel produced by the gasifier has a heating value ranging from 920 to 1150 kcal/m3, making it clean-burning. Its primary components consist of 19% to 23% carbon monoxide and 17% to 21% hydrogen. This study offers a unique investigation into the gasification behavior of the organic fraction of OFMSW in a downdraft gasifier, with an emphasis on optimizing operational parameters and evaluating the yield and quality of syngas. Although gasification has been widely studied as a thermochemical conversion method for biomass, the specific performance of OFMSW in this process has received limited attention. By focusing on this underexplored area, the study enhances the understanding of OFMSW's potential in gasification and its contribution to sustainable energy production, thereby addressing key issues in both waste management and renewable energy generation.

Precision and uncertainty in natural gas calorific value estimation: advanced combinatorial predictive models for complex pipeline systems

Abstract In recent years, natural gas pipelines have been characterized by multiple intake points, the mixing of different gas sources, and significant variations in gas quality. The existing volumetric measurement system is no longer suitable for the development and operation of natural gas pipelines in China. To ensure accurate and equitable implementation of natural gas measurement, there is a gradual shift towards energy measurement. However, due to numerous measurement interfaces, installing chromatographs at all measurement stations would lead to substantial investment costs. Therefore, predicting the calorific value of natural gas is a key technology for energy measurement. In view of the issues existing in the current methods of obtaining natural gas calorific value, different prediction models of natural gas calorific value are constructed. According to the influencing factors of natural gas calorific value, the uncertainty evaluation is carried out, and the accuracy of different calorific value prediction models is analyzed by case data. The maximum error of regression equation (RE), response surface analysis (RSA), BP neural network and genetic algorithm (GA) prediction model is 2.29%, 0.43%, 0.59% and 0.45% respectively. However, the combined calorific value (CCV)prediction model is 0.41%. The results indicate that the predicted value calculated by the CCV prediction model is closer to the actual value and has higher prediction performance, which provides a new method for the calorific value prediction and measurement management of natural gas.

U-Net Semantic Segmentation-Based Calorific Value Estimation of Straw Multifuels for Combined Heat and Power Generation Processes

This paper proposes a system for real-time estimation of the calorific value of mixed straw fuels based on an improved U-Net semantic segmentation model. This system aims to address the uncertainty in heat and power generation per unit time in combined heat and power generation (CHPG) systems caused by fluctuations in the calorific value of straw fuels. The system integrates an industrial camera, moisture detector, and quality sensors to capture images of the multi-fuel straw. It applies the improved U-Net segmentation network for semantic segmentation of the images, accurately calculating the proportion of each type of straw. The improved U-Net network introduces a self-attention mechanism in the skip connections of the final layer of the encoder, replacing traditional convolutions by depthwise separable convolutions, as well as replacing the traditional convolutional bottleneck layers with Transformer encoder. These changes ensure that the model achieves high segmentation accuracy and strong generalization capability while maintaining good real-time performance. The semantic segmentation results of the straw images are used to calculate the proportions of different types of straw and, combined with moisture content and quality data, the calorific value of the mixed fuel is estimated in real time based on the elemental composition of each straw type. Validation using images captured from an actual thermal power plant shows that, under the same conditions, the proposed model has only a 0.2% decrease in accuracy compared to the traditional U-Net segmentation network, while the number of parameters is significantly reduced by 74%, and inference speed is improved 23%.

Performance analysis of biodiesel derived from pork fat of swill and concentrate-fed pigs

With the escalating demand for sustainable energy solutions, unconventional sources are gaining attention, including the utilisation of pork fat for biodiesel production. This study investigates the influence of different pig feeding systems, namely swill and concentrate, on the characteristics and performance of biodiesel derived from pork oil. Twelve Large White Yorkshire piglets were divided into two treatments: one following standard feeding practices (T1), and the other exclusively fed with swill (T2). The pigs were slaughtered, and their fat was processed into biodiesel through transesterification. The fuel properties of the biodiesel were analysed, including kinematic viscosity, flash point, fire point, gross calorific value, and low-temperature fuel properties. Additionally, engine performance and exhaust emissions of a biodiesel blend (B20) derived from pork oil were evaluated and compared to commercial diesel fuel using a Kirloskar single-cylinder diesel engine connected to an eddy current dynamometer. Results indicate that both T1 and T2 B20 biodiesel exhibit favourable characteristics comparable to diesel, with promising fuel density, injection duration, mass flow rate, brake-specific fuel consumption, and brake thermal efficiency across various load conditions. Moreover, critical factors such as cetane number and gross calorific value suggest suitable ignition qualities and energy content, highlighting the potential of pork oil-derived biodiesel as a sustainable alternative fuel source. Keywords: Biodiesel, pork fat, swill, concentrate feeding systems

Comparative Analysis of Domestic Production and Import of Hard Coal in Poland: Conclusions for Energy Policy and Competitiveness

In many energy policies, including Poland’s, environmental priorities clash with the issue of energy security. With these contradictions in mind, the main objective of the article is a comparative analysis of domestic production and imports of hard coal in Poland and the formulation of conclusions for energy policy and competitiveness. The analysis covers the years 2018–2023 and concerns three issues: the volume and directions of coal imports to Poland, the qualitative and price competitiveness of coal, and the possibility of substituting imported coal with domestic coal. The research used statistical analysis. Indicators of structure and dynamics as well as comparative analysis were also used. The analysis shows that the structure of coal importers to Poland is quite diverse and includes many geographic directions. However, until 2021, it was dominated by Russia, followed by Colombia, indicating a fairly homogeneous supply market and a continuing tendency to depend on a single importer. Analysis of qualitative competitiveness confirms the existence of balance and industrial resources whose quality parameters (sulfur content, ash content, and calorific value) are comparable to and better than those of imported coal. Polish hard coal can also compete with imported coal in terms of price. From 2021 to 2023, it was clearly cheaper than foreign coal. In the above circumstances, it is quite difficult to unequivocally assess the reasons for importing coal to Poland and to justify dependence on external suppliers. This is especially relevant since domestic mining in 2020–2023 remains stable (periodically even increasing), which does not indicate a decisive shift away from coal as an energy resource.

Desulfurization of pyrolytic oils from waste tire pyrolysis in a fluidized bed reactor with boron nitride adsorbents

The study focused on producing hexagonal boron nitride (hBN) as an adsorbent which provides high efficiency in desulfurization processes. The synthesized hBN is used for sulfur removal from liquid fuel derived from end-of-life tires (ELTs). Characterization of hBN was performed using FTIR, XRD, TGA, and SEM-EDS analyses. Liquid fuel was produced in a fluidized bed reactor at 550 °C under a nitrogen gas flow. Post-desulfurization, the fuel's density, water content, and calorific value increased, while sulfur content and flash point decreased, with sulfur content showing a significant reduction of 79.23 %. The desulfurized fuel (PS-A) exhibited better combustion characteristics and closely resembled diesel fuel performance, though it slightly reduced engine effective efficiency by 1.06 % compared to diesel. Both PS-A and pre-desulfurized fuel (PS-B) significantly reduced soot emissions by 23.28 % and 20.81 %, respectively, compared to diesel. Additionally, CO emissions were lower for PS-A and PS-B, with reductions of 4.35 % and 2.00 %, respectively. However, CO2 emissions increased by 1.60 % for PS-A and 0.86 % for PS-B, attributed to higher fuel consumption. Overall, hBN effectively reduced sulfur content and improved several fuel properties of pyrolytic liquids. The study highlights the environmental and economic benefits of enhancing ELT-derived liquid fuels and suggests potential applications in real systems, serving as a foundation for new technologies and projects.