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Current State of Development of Demand-Driven Biogas Plants in Poland
Renewable energy sources (RES) are the foundation of the ongoing energy transition in Poland and worldwide. However, increased use of RES has brought several challenges, as most of these sources are dependent on weather conditions. The instability and lack of control over electricity production lead to both overloads and power shortages in transmission and distribution networks. A significant advantage of biogas plants over sources such as photovoltaics or wind turbines is their ability to control electricity generation and align it with actual demand. Biogas produced during fermentation can be temporarily stored in a biogas tank above the digester and later used in an enlarged CHP unit to generate electricity and heat during peak demand periods. While demand-driven biogas plants operate similarly to traditional installations, their development requires navigating regulatory and administrative procedures, particularly those related to the grid connection of the generated electricity. In Poland, it has only recently become possible to obtain grid connection conditions for such installations, following the adoption of the Act of 28 July 2023, which amended the Energy Law and certain other acts. However, the biogas sector still faces challenges, particularly the need for effective incentive mechanisms and the removal of regulatory and economic barriers, especially given its estimated potential of up to 7.4 GW.
Smart Resource Management and Energy-Efficient Regimes for Greenhouse Vegetable Production
Greenhouse vegetable production faces significant challenges due to the non-stationary and nonlinear dynamics of the cultivation environment, which demand adaptive and intelligent control strategies. This study presents an intelligent control system for greenhouse complexes based on artificial neural networks and fuzzy logic, optimized using genetic algorithms. The proposed system dynamically adjusts PI controller parameters to maintain optimal microclimatic conditions, including temperature and humidity, enhancing resource efficiency. Comparative analyses demonstrate that the genetic algorithm-based tuning outperforms traditional and fuzzy adaptation methods, achieving superior transient response with reduced overshoot and settling time. Implementation of the intelligent control system results in energy savings of 10–12% compared to conventional stabilization algorithms, while improving decision-making efficiency for electrotechnical subsystems such as heating and ventilation. These findings support the development of resource-efficient cultivation regimes that reduce energy consumption, stabilize agrotechnical parameters, and increase profitability in greenhouse vegetable production. The approach offers a scalable and adaptable solution for modern greenhouse automation under varying environmental conditions.
The Effect of Corn Ensiling Methods on Digestibility and Biogas Yield
This study investigates the impact of different corn silage preparation methods, namely the traditional and Shredlage methods, on digestibility and biogas yield in anaerobic digestion and its nutritional value—the first complex study of its kind. Key parameters of both silage types were analyzed, including chemical composition, fiber content, and elemental makeup. Methane and biogas production were assessed under standardized fermentation conditions. The results showed that the Shredlage method, characterized by more intensive chopping, led to higher biogas and methane yields per unit of organic dry matter compared to traditional silage. This improvement is attributed to enhanced digestibility due to the lower content of neutral detergent fiber (NDF), acid detergent fiber (ADF), and crude fiber in Shredlage. An elemental analysis revealed slight differences in carbon-to-nitrogen (C/N) ratios, with both silages showing values suitable for efficient fermentation. Despite minor variations in mineral content, Shredlage demonstrated greater efficiency in biogas production, particularly for rapid fermentation processes. The findings underscore the importance of silage preparation techniques in optimizing biogas yield and suggest Shredlage as a superior option for enhancing energy recovery in biogas plants. Future work should explore the economic trade-offs and scalability of these methods.
Optimization of Straw Particle Size for Enhanced Biogas Production: A Comparative Study of Wheat and Rapeseed Straw
Biogas production from lignocellulosic biomass, such as wheat and rapeseed straw, is an essential strategy for sustainable energy generation. However, the efficiency of anaerobic digestion depends on the physical characteristics of the substrate, particularly the particle size, which influences microbial accessibility and biogas yield. This study aims to optimize straw particle size for enhanced methane production by evaluating different fractionation levels. The straw was processed using a hammer mill and separated into three size fractions (2.4 mm, 1 mm) alongside non-separated and finely ground (2 mm) samples. The chemical composition was analyzed using X-ray fluorescence (XRF), and key parameters such as pH, dry matter (DM), and organic dry matter (ODM) were assessed. The results indicated that rapeseed straw had lower pH (6.05) and DM than wheat straw (7.01). Biogas yield analysis demonstrated that methane production varied with particle size. For rapeseed straw, non-separated samples achieved the highest methane yield (132.87 m3 Mg⁻1), whereas for wheat straw, methane yield decreased with increased fragmentation, with the highest yield observed for non-separated material (206.65 m3 Mg⁻1). The carbon-to-nitrogen (C/N) ratio was highest in rapeseed straw (153.82), potentially limiting microbial activity, while finer fractions had more balanced ratios. These findings highlight the importance of mechanical pretreatment in optimizing biogas production and provide insights into improving the efficiency of straw-based anaerobic digestion systems.
Wear Detection of Extruder Elements Based on Current Signature by Means of a Continuous Wavelet Transform
Assessing the wear of components in a single-screw extruder and its condition during the process is difficult. In this context, wavelet analysis was used to investigate the wear condition of extruder elements, which yielded data on current waveforms obtained from 1 kHz frequency converters. To date, no tests of this type have been conducted on single-screw food extruders, which further emphasizes the relevance of the research undertaken by the authors. Experimental tests have been conducted to verify the hypothesis that it is possible to assess the level of wear of the working elements of an extruder by monitoring the variations in the frequencies on the current spectrum using wavelet analysis tools. The root mean square (RMS) values of the current were compared for two configurations of the working elements of the device, i.e., new and used. Observation of the frequency variations of the current spectrum values using wavelet analysis tools can provide valuable information on the technical condition of the working elements of an industrial extruder. Therefore, they can indicate the need for prompt replacement of friction elements in order to improve the efficiency and performance of the machine.
Determination of the Impact of Extruded Soybean Press Cake on Rearing and Health Indices of Piglets
The study was conducted to evaluate the alternative to imported soybean meal—extruded soybean press cake—in feeding weaning pigs. The experiment was carried out with 20 35-day-old weaned pigs weighing about 8.8 kg, divided into 2 groups (10 pigs in each) differing in the main protein source: group I—control, solvent-extraction soybean meal, group II— extruded soybean press cake. The feed mixtures were iso-protein and iso-energetic. After 35 days of feeding, the pigs were slaughtered. The samples of blood, intestinal tissue and digesta, meat, and back fat were collected for analyses. Replacement of soybean meal with extruded soybean press cake in the weaners’ diet had no statistically significant effect on growth performance and feed utilization. Histomorphometry analysis of the intestines did not indicate any harmful changes. The soybean press cake did not affect the sum of volatile fatty acids in the large intestine, but the ammonia concentration was lower in the distal colon (p ≤ 0.05). It was found that the extruded soybean press cake in the feed significantly affected the fatty acid profile (p ≤ 0.05) of meat and back fat, increasing the amount of PUFAs; however, no negative impact on the durability of meat and back fat during storage was noted. In conclusion, the study confirmed the possibility of completely replacing solvent-extraction soybean meal with extruded soybean press cake in the feeding of weaned pigs.
Methodology of development of intellectual energy efficient system of control of temperature-humidity regime in industrial heat
Methods of improving the quality of regulation of technological parameters by combining various intelligent control algorithms in one automation system, which helps to reduce energy costs by 10-13%, are analyzed. It has been established that heating and ventilation systems have the highest energy consumption for indoor buildings (on average, more than 4,000 m3 of natural gas and almost 1,000 kWh of electricity are consumed per day for heating and ventilation in an industrial greenhouse. Correlation analysis of links between external disturbances and energy costs that ensure compliance with the technology of plant production, confirmed the hypothesis of conditions of uncertainty in the operation of industrial greenhouses are formed by random disturbances, incomplete information about the biological component, with linear correlation coefficients not exceeding r<0.35. both for forecasting energy costs and for the formation of energy efficient management strategies. Based on the use of fuzzy logic methods and genetic algorithm, models for finding and using optimal parameters of PI controller settings adapted to changes in the operating conditions of the automation system have been developed and studied. This provides better regulation in conditions of uncertainty, the time of regulation, over-regulation is reduced by two to three times. To create an energy-efficient microclimate management system in industrial greenhouses, operating in conditions of uncertainty, a neural network model for predicting the energy consumption of natural gas and electricity has been developed. The input parameters of the neural network forecasting model are: the value of external and internal air temperatures of the greenhouse, the value of relative humidity, the solar radiation absorbed by the greenhouse and the level of carbon dioxide in the greenhouse. The outputs of the forecasting model are the values of natural gas and electricity costs. The structural and functional scheme of the temperature and humidity control automation system in industrial greenhouses has been improved by combining intelligent algorithms for stabilizing the operation of technological equipment at the lower management level and optimizing energy costs by forecasting them at the upper level. The introduction of such a system saves up to 13% on natural gas for heating and up to 10% on electricity.
Research on the Morphology of the Working Surfaces of Contacts Used in Starters in the Agro-Industrial Sector
The operational suitability of electromagnetic starters equipped with experimental contacts has been substantiated within their use in electrical installations of the agro-industrial sector, which may be affected by the environments containing aggressive components. Tests on commutation wear resistance and investigations on arc erosion of the series-produced contact parts of such starters as PML-1100O4, PML-2100O4 (versions A and B; contact material—CpH-90, CpM-0,2 + M1, KMK-A10m, respectively) and PML-1100O4 starter with the experimental copper-based contact parts (Cu + Nb + Zr + Y2O3; Cu + Mo + MoO3 + C + Ni; Cu + Cr + TiB2 + Nb + C + Zr) have been conducted. The influence of energy parameters of a commutated circuit on the value of electro-erosion wear, the morphology of the working surfaces of contacts and contact resistance have been determined. Investigation results have been obtained by conducting a set of tests on electromagnetic starters at the experimental plant that simulates the operating conditions of the AC-3 application category. The impact of the electric arc of alternative current on the arc erosion of silver-based and copper-based contact materials have been determined by using a scanning electron microscope Cambridge Stereoscan S4-10 equipped with an attachment for X-ray spectroscopic analysis, Link System-290 and an X-ray microanalyzer Camebax SX-50 (CAMECA, Gennevilliers, France). A metallographic analysis of the contact surfaces has been conducted, which contributed to the determination of the patterns of erosive destruction of bridging contacts based on Ag and Cu. Evolution of the eroded morphology of contacts and the surface components of electrical contacts under the influence of an arc have been characterized. In addition, contact mass loss and the dependence of contact resistance have been studied. When manufacturing the experimental contacts, it is possible to abandon the use of silver, which is significantly cost saving, and not to use dangerous contact additives that are hazardous to the environment and people’s health.