In the current context of environmental requirements, solid renewable biomass is becoming one of the main viable energy sources that can replace fossil fuels. This paper focuses on evaluating the morphological structure and properties of three fruit trees that are widely grown on the territory of Moldova, both on the left and the right banks of the Prut River: the apricot, the peach, and the plum. The wood biomass was characterized by scanning electron microscopy (SEM Quanta 200 3D), X-ray analysis (Xpert PRO MPD), and FT-IR analysis. A chemical analysis including the determination of extractive substances, lignin content, and the detection of hemicelluloses content was carried out for all wood samples. In addition, the net calorific value was determined by measuring the calorific value at constant volume, in compliance with the requirements of the EN ISO 18125:2017 standard. According to the obtained results, in terms of maximum calorific output and lignin and minimum ash content, plum appeared to be the best solid biomass resource. However, the other two trees also showed promising results for becoming important sources of wood biomass for pellet production.

The use of biomass mixtures as a feedstock in the production of pellets requires optimization of the percentages of the components, since interactions occur during combustion between the components forming the blend (lignin, cellulose, and hemicellulose), affecting characteristics of pellets such as calorific value, ash content, fine fraction content, bulk density, and mechanical durability. Our study focuses on the assessment of the quality of pellets produced from biomass blends generated from pruning seabuckthorn and blackberry mixed with wheat straw. The results of literature data analysis and laboratory research show that wheat straw pellets exhibited the lowest calorific value (15.2 ± 0.2 MJ/Kg) and the highest ash content (5.7 ± 0.18%) while seabuckthorn and blackberry biomass pellets possessed significantly higher calorific value with low ash content. According to the maximization of the mixtures taken in the study, it was proved that the addition of up to 25% wheat straw remaining seabuckthorn biomass provides all the qualitative indicators specified by ENPlus 3 standards. The straw content can be increased up to 35% if 10–20% of blackberry biomass is added to the mixture. The production of pellets from biomass mixtures with an optimized composition, meeting the requirements of EN3Plus standards, will benefit the environment and the agricultural economy by replacing polluting fuels and making optimal use of straw and fruit tree pruning residues.

This paper explores the utilization of biomass resources derived from vineyard residues for producing densified solid biofuels in the Republic of Moldova, with the aim of quantitatively and qualitatively evaluating the residue from vine pruning, focusing on the feasibility of its use as raw material for the production of briquettes and pellets. The methodology includes the analysis of statistical data, as well as experimental investigations conducted at the Scientific Laboratory of Solid Biofuels of the Technical University of Moldova. Waste biomass samples were collected from various vineyards in the different districts of all three regions of the country, focusing on regions with significant plantations. Both quantitative and qualitative aspects of the biomass were assessed, considering the moisture content, calorific value, and ash content. It was found that about 1013 kg/ha of waste biomass is generated from the pruning of technical grape varieties with a net calorific value of 15.6 MJ/kg at a moisture content of 10 wt.% and about 1044 kg/ha with a calorific value of 16.4 MJ/kg from the table ones; both with an average ash content of 3 wt.%. The results indicated that vineyard pruning residues in the Republic of Moldova could provide a substantial biomass source, with an estimated total energy potential of approximately 370 TJ/y (80% located in the Southern region); they also highlighted the need for technological advancements and quality assurance procedures through which to ensure the efficiency and sustainability of biofuel production. The conclusions emphasize the numerous benefits of utilizing viticultural residue, both economically and ecologically, contributing to the sustainable development of the viticulture industry in the Republic of Moldova, as well as environmental protection.

The production of pellets has recently experienced a sudden upward trend worldwide, including the Republic of Moldova and Romania, especially due to the energy crisis caused by the war in Ukraine and rapid depletion of fossil energy sources. The widespread use of pellets has several reasons: it is an eco-friendly fuel, it allows the automation of the combustion process, and it can be easily produced in any region that has enough raw materials. The calorific value of pellets is the main characteristic feature that determines their price and is used in combustion engineering to find out the thermal efficiency of combustion plants. This paper synthesizes the results regarding the calorific value of the pellets produced from different types of plant biomass specific to the Republic of Moldova and the counties adjacent to the river Prut in Romania. The research has been carried out within the Solid Biofuels Laboratory, SAUM using standard methods of testing densified solid biofuels. The experimental results obtained in this study showed that the pellets produced from arboriculture residues, residues generated from vine pruning, table varieties, as well as those produced from sunflower seed husk have a calorific value equal to or greater than 16.5 MJ/kg, i.e., they meet ENPlus 3 requirements.

Quality of pellets produced from agricultural wood residues specific to the Prut river basin This paper presents an overview of the prospects for the use of agricultural wood residues, specific to the climatic zone adjacent to the Prut River and the qualitative characteristics of densified solid biofuels in the form of pellets produced from the main types of the agricultural wood biomass, taken from agricultural plantations in the Republic of Moldova and Botosani, Iasi, Vaslui and Galați counties in Romania. The aim of the paper is to establish the energy potential of the main indigenous agricultural wood residues and to analyze the quality of the pellets produced from these residues. The research results showed that the pellets produced from the studied agricultural residues mainly meet ENPlus 3 requirements for most qualitative parameters, except for those produced from blackberry and currant residues. Residues from the prunning of some types of fruit shrubs can be used to produce pellets by creating mixtures of different proportions, and their qualitative characteristics can be significantly improved by thermo-chemical pre-treatment of the raw material. Keywords: plant biomass, densified solid biofuels, pellets, biofuel, energy potential, agricultural wood residues.

This article presents an in-depth analysis of the application of thermal deposition techniques, in particular thermal spraying, to improve the properties of materials used in agricultural components that work the soil, such as agricultural plows (mainshare and foreshare). Due to the difficult operating conditions, characterized by abrasive wear, mechanical shocks, and chemical exposure from various soils, these surface coatings aim to increase the durability and corrosion resistance of the materials of components intended for working with the soil. The study investigates thermal deposition methods and their effects on the microstructure, hardness, and friction resistance of the obtained layers. The study highlights experiments that reveal significant improvements in mechanical properties, highlighting superior behavior in real conditions of agricultural use. Nevertheless, soil types significantly influence the abrasive wear rate of the components and also their corrosion, which depends on the soil pH. The results confirm that the use of thermal deposition represents a sustainable and effective solution for extending the life of plows, thus reducing maintenance costs and increasing the efficiency of agricultural processes. This research contributes to the optimization of agricultural equipment, providing an innovative approach for adapting plows to the increasing demands of agricultural exploitation.