• Energy Research

The accumulation of beach wracks poses significant challenges to coastal management, particularly in tourist areas, affecting environmental quality and aesthetics. This study explores the qualitative characteristics of beach wrack as a biofuel source for combustion appliances. Samples collected from beaches in Veneto, Italy, were analyzed according to EN ISO standards for solid biofuels. Proximate and ultimate analysis, heating value, and ash melting behaviour were determined. Raw samples (BW-R) exhibited high moisture content (77%), a substantial ash content (44%), and low heating value (10.7 MJ kg-1), making them unsuitable for direct energy applications. Pretreatments were performed to enhance the properties of the material. One portion was mechanically sieved (BW-S) to remove sand, while another was sieved and washed (BWSW) to remove the remaining salt and sand. Sieving reduced the ash content to 24% and increased the heating value to 15.3 MJ kg-1. The key improvements came from washing and sieving, which lowered ash content to 13% and increased heating value to 18.1 MJ kg-1. Washing also raised the ash deformation temperature to 1,290 °C, enhancing thermal stability. Pretreatments increased C and H content while reducing S and O, with no significant change in N. Due to high ash content, mixing with sawdust was necessary, resulting in mixtures showing better properties: 4.0% ash for Mix30 (30% beach wrack, 70% sawdust) and 6.9% for Mix50 (50% each) and increased heating values. However, challenges remain in converting beach wrack into viable fuel due to material losses during pretreatment, high costs, and environmental concerns from plastics.

Abstract Open burning of agricultural waste is still a common practice as it is a rapid method for waste disposal, although natural biomass, including agriculture residues, can be exploited as a renewable energy source. We assessed the viability and sustainability of using vineyard pruning residues, as wood chips, for energy conversion. Wood chips, obtained from vineyards in the Prosecco DOCG region (Italy), were characterized in terms of chemical composition, calorific value, ash content and humidity. Combustion tests were performed in a medium-size biomass boiler (maximum power 500 kW) to assess the viability of the approach in terms of sustainable steady-state combustion. Primary emissions of both macro- and micro-pollutants were measured to assess the environmental impact. An analytical method was purposely developed for the determination of polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) in three matrices: fly ashes, condensate and gas. The results showed that vineyard pruning residues can be used for energy conversion in medium- and large-scale biomass boilers. Primary emissions of measured pollutants were all below limit values set by current European legislation except for particulate matter, for which current available abatement technologies are required to contain emissions, thus making the use of vineyard pruning residues unsuitable for combustion in domestic appliances where such technologies are not installed. Bottom ashes produced during combustion were also characterized to assess whether they can be recycled in the vineyard as soil amendments/fertilizers. Copper content in combustion ashes exceeded limit values for ashes to be used as fertilizers in agricultural fields for some European countries but not for others, indicating that ashes may need to be disposed as waste.

Nowadays the spread of precision forestry has led to the possibility of collecting data related to forest machines for an extended period and with enough precision to support decisions in the optimization of harvesting strategies in terms of technological and environmental efficiency. This study aims to evaluate the effective benefit of automatic data collection through the fleet management system (FMS) of two forest harvesters and two forwarders in pine forests in Poland. The study also aims to determine how the use of FMS can help forest companies to manage their fleet and take advantage of long-term monitoring. Focusing on performance indicators of fuel consumption and CO2 emissions, as well as on the engine parameters from the Can Bus data, the exploration of data was performed following a Big Data approach, from the creation of an aggregate dataset, pre-elaboration (data cleaning, exploration, selection, etc.) using GIS and R software. The investigation has considered the machine productivity, in the case of the harvesters, and the specific fuel consumption of each machine studied, as well as the time used by each of them during the different working cycle activities and the total amount of timber processed. The main results indicate an average emission of 2.1 kg of CO2 eq/m3 for the harvesters and 2.56 kg of CO2 eq/m3 for the forwarders, which equates in total to 0.24% of the carbon stored in one cubic meter of wood.

Abstract Bioenergy production is optimal when the energy production process is both efficient and benefits from local resources. Energetic and exergetic analyses are applied to highlight efficiency differences between small-size systems that are based on the co-generation of heating and power (CHP) versus the co-generation of heating and power with steam production (CHP-S). Both systems use the Organic fluid Rankine Cycle (ORC). The recovery of heat from flue gases is considered to be a way of increasing energy efficiency. In the CHP-S case, steam (at low pressure) is used to extract essential oils from fresh twigs and needles of coniferous trees throughout a steam distillation process. When the systems work at a thermal combustion power of 1350 kW, energetic analysis shows that the energy efficiency of the CHP-S plant (89.4%) is higher than that of the CHP plant (77.9%). Exergetic analysis shows that the efficiency of the CHP-S plant is 2.2% higher than that of the CHP plant.

Abstract Color of wood pellets is mainly affected by the feedstock material used for their production and which composition and characteristic affect the final product quality. Pellets made from pure wood are light in color and have low ash content, while pellets made from different mixtures of wood and bark or foliage are generally darker and richer in minerals. This study aims to verify the correlation between color and quality parameters of wood pellets available on the Italian market. All the samples were analyzed following the procedures laid down by the European Norms (EN) on solid biofuels for moisture, ash, calorific value, durability, bulk and solid density. The acquisition of the images was done with two techniques: the CIE L ∗ a ∗ b ∗ color space and RGB-HSV color spaces. Canonical correlation analysis (CCA) was performed with CIE- L ∗ a ∗ b , RGB and HSV separately showing for all the color components good degree of correlation with ash content of pellets. The PCA analysis on two principal components (total explained variance: 64.2%) showed a clear color gradient moving form good to medium or low quality parameters. This pattern is confirmed by the clustering of certified pellets in the region of lightest samples. The calculation of Δ E and ΔRGB showed a good discrimination level between whole pellets samples and their sawdust, and between ones with high and low ash content. The visual predictability of pellets quality on the basis of their color is however not so sharp when considering samples with similar colors. The industrial applicability of such methods for the evaluation of pellets quality is desirable for RGB methodologies that are less expensive and more reliable in working condition, given that specific color calibration is performed.

The global charcoal trade is steadily growing, with high-income countries importing significant quantities of this material from regions where its production is often associated with severe environmental issues, including forest overexploitation, illegal logging, and environmental pollution. Promoting local charcoal production in high-income countries is crucial to addressing these challenges. In this study, we have chosen to focus on the European context, specifically emphasizing Italy as a case study. Our study aimed to comprehensively compare five distinct charcoal production systems, including both traditional and modern solutions, with a specific focus on evaluating the quality of the resulting charcoal. Additionally, improvements were evaluated to enhance production efficiency. Traditional systems cannot satisfy production requests, resulting in inefficiencies in manpower, costs, times, and yield. Conversely, recent innovations consider mobile and stationary kiln prototypes. Mobile kilns offer flexibility and cost savings but require operator expertise, limit automation, and have long cycles. In contrast, stationary systems operate continuously, increasing productivity and efficiency, despite higher investment costs. Notably, charcoal quality showed minimal differences. These findings highlighted the potential of new technologies to enhance efficiency, reduce cost and environmental impact, and promote sustainable charcoal production.

Abstract This study uses Geographical Information Systems (GIS) to estimate woody biomass supply and demand in Northeast Italy. Demand is estimated using census data on boilers and supply calculations are derived from data on timber harvests and mill operations. The analysis is done with GIS using Large Scale Analysis at a broader resolution (for the entire region) and Small Scale Analysis at a finer resolution (for the Primiero valley only), with added information on tree species, road networks and logging systems. From large scale analysis demand results to be about 163 000 MWh, corresponding to about 71 000 tonnes per year of fuel, with a moisture content of 50 percent. As shown by results from a small scale analysis, the Primiero valley has a deficit of 21 400 MWh. A more thorough analysis shows that 93 percent of logging operations can be performed with cable cranes and that high quality chips derived from forest biomass amount to only 335 MWh of energy (20 percent of the total). The deficit calculated at a small scale confirms the value obtained in the large scale calculation. Analysis of the demand-supply balance will be helpful for decision makers and politicians and should be taken into account when allocating subsidies for new boilers or district heating.

Abstract More sustainable scenarios in the bioenergy sector can be achieved when biomass exploitation is based on eco-efficient supply chains. Regarding this, grass as a by-product obtained from landscape management could provide a large quantity of biomass potentially utilizable in the Anaerobic Digestion (AD) supply chain. This study assessed the energy and greenhouse gases (GHG) impacts of grass obtained from the landscape management of riverbanks. A study area of a land reclamation authority was investigated by interpreting high resolution spatial data and determination of the biomass yield. In addition, an inventory was made of the grass production chain. An energy analysis was performed using the Cumulative Energy Demand method (CED), while the GHG balance of grass AD was calculated based on CO2 equivalents. Special attention was also given to the logistic approaches: two different supply systems were evaluated in order to determine the best supply chain for this feedstock. The results show that the biomass yield of riverbank grass amounts to 13 t f.m /ha (4.8 t d.m /ha) while the energy utilization of grass determines a saving on fossil energy of about 2.6–2.4 GJ/t f.m. (7.0–6.4 GJ/t d.m. ) and on GHG equivalent emissions of about 86–67 kg CO2eq /t f.m. (233–181 kg CO2eq /t d.m. ) depending on supply distance and logistic approach. In this regard, the Indirect Logistic Approach (ILA) achieves the best performance in terms of the reduction of fossil energy and GHG emissions. The results suggest positive prospects for the integration of grass from non-cultivated areas into the AD supply chain in order to mitigate the requirement for agricultural feedstock and obtain a positive return, in terms of energy and emissions saved, from landscape management operations.