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Biomass materials play a key role in the renewable energy market as they can serve as a suitable alternative to fossil fuels. However, the quality of the material entering bioenergy plants is often a cause of technical concern. Biomass quality assessment is crucial not only for energy characterization but also for environmental and operational aspects. The goal of this study is to characterize and classify the biomasses used by Italian power plants with reference to the quality classes stated by the ISO standard 17225:2021. A further objective is to verify the ability of the standard to classify heterogeneous and specific biomasses. In this study, more than 900 biomass samples were analyzed. The samples were collected from several Italian power plants with >5 MWe between 2010 and 2020, and the most important physical and chemical parameters were analyzed according to the international standards of reference. The results of the analyses were collected in a large dataset used for subsequent statistical analyses. Statistical analyses applied are Principal Component Analysis and Pearson correlation maps, which showed that the ash content is a fundamental and ideal parameter to assess the biomass quality. Results obtained demonstrate that herbaceous biomasses are of low quality mainly due to the high ash content; a relatively low ash content was found for woody biomasses. [ABSTRACT FROM AUTHOR]

The chemical composition of woody biomass directly influences its thermal degradation and, subsequently, the selection of processes and technologies used for its conversion into energy or value-added products. Thus, the present study aimed to evaluate the thermal behavior and chemical-physical characteristics of three different woody biomass species (hardwood, softwood and chemically-treated wood) using thermogravimetric and characterization analysis based on ISO 16948, ISO 18125 and ISO 18122 methods. The main findings show that the most significant trend of mass loss, around 70%, in the thermal degradation of the different species of woody biomass occurred between 150 °C and 500 °C and that the residual mass at 650 °C was between 13% and 24%. Although the three species of woody biomass showed a high average energy content (19.60 MJ/kg), softwood samples had a more stable thermal degradation than hardwoods and chemically-treated woods. [ABSTRACT FROM AUTHOR]

Replacing fossil energy sources with renewable energy sources is a key strategic action to limit environmental issues. To achieve this goal, substitution with biomass is beneficial due to its versatility in various fields. In terms of circular economy and sustainability, the possibility of energy exploitation of residual biomass is particularly desirable in small-medium enterprises. The use of supply chain by-products can improve sustainability and create opportunities for companies. The purpose of this study is to evaluate the suitability of residual biomass of conifers and broad-leaved trees to produce quality pellets using an agri-pellet machine activated by the power take-off of a tractor. This system can be employed at the farm level. Wood biomass of four species was tested; poplar, stone pine, black locust, and oak. Wood chips samples were analyzed to determine their qualitative characteristics following the technical standard ISO 17225-4. Based on the results, different wood blends were created to produce pellets, subsequently characterized according to ISO 17225-2. The analyses carried out on wood chips and pellets were bulk density, moisture, ash content, calorific value, elemental composition, chlorine, sulfur, and heavy metals. In addition, particles size was measured only for wood chips, while the length, diameter, mechanical durability, and ash melting behaviors were determined only for pellets. Some of the analyzed mixtures show acceptable values according to the current ISO technical standards. The values related to the apparent pellet bulk density and the durability test highlight that not all the mixtures are suitable to produce quality pellets. Results also represent a good starting point for future studies. [ABSTRACT FROM AUTHOR]

Moisture content is the most relevant quality parameter for wood fuels. Effective and fast determination of moisture of incoming feedstock is essential in the management of bioenergy facilities. The availability of fast and reliable moisture meters based on innovative technologies simplifies this task. However, in Mediterranean conditions the inherent variability of wood fuels calls for a careful sampling strategy if representative results are required while facing acceptable analytic costs. The present study is aimed at measuring the fuel heterogeneity and defining accordingly the appropriate number of samples to be analyzed in order to get reliable moisture-content results. A total of 70 truckloads (about 2270 t of woodchips) were sampled during commercial operations in two different seasons. Five samples were collected from each load and measured with standard method and magnetic resonance gauge. Results show that the variability of moisture content is influenced by mixing of species and storage of biomass. Heterogeneity can vary greatly also within single truckloads, to the point that three samples are needed to achieve about 90% of estimates within the desired precision limits. In the case of larger lots, such as barge or ship loads, 20 samples can provide sufficient precision in most scenarios. [ABSTRACT FROM AUTHOR]

This study focuses on verifying the influence of some additives in the ash melting process of herbaceous biomass, developing a pelletized biofuel from the mixture of herbaceous biomass and various inorganic substances through a series of experimental tests. Therefore, different materials were sampled, chemically characterized and combined in mixtures of low-melting biomass materials. Tests were performed with various inorganics products added directly on the relative ashes to verify the interaction between the two systems. Subsequently, herbaceous biomass pellets containing growing amounts of additive were produced, verifying their effectiveness by analyzing the ash melting temperatures and adopting the PASSA test, that investigates the size of the ashes after incinerating the biomass in a muffle. The same method was then used to evaluate the ashes of an industrial boiler. Results show that the addition of inorganic additives in the extent of 3–5% by weight determines an increase in deformation temperatures over 547 °C for several biomass materials and additives. Tests carried out on forage pellets made with alfalfa and CaO as additive brought instead to an increase in deformation temperature between 43 and 107 °C. This work could be of interest in the evaluation of the energy reuse of herbaceous materials that would otherwise be considered as waste, and also it suggests the possibility of using egg shells as inorganic additives in accordance to the circular economy approach. Furthermore, the additivation level of these pelletized biofuel is perfectly in line with the provisions of ISO 17225-6 for non-woody pellets (≤5% weight). [ABSTRACT FROM AUTHOR]