• Energy Research

Abstract In Italy, more than 1150 agricultural anaerobic digestion (AD) plants are currently running. Their concentration in specific areas resulted in an increase in the biomass price and transport distances. For the AD plants located on farms with small area, often the feedstock are purchased on the market. However, when transport distances increase, it can be less expensive to buy biomasses with high energy density. With this regard, maize experimental tests were carried out to evaluate the methane production by harvesting the whole plant, the plant cut at 0.75 m and only the ear. The aim of this paper is to evaluate the economic performances of biogas plants fed with different maize silages by considering increasing extra-farm transport distances. Two different scenarios were considered with regard to the subsidy framework and to the maize biomass yield. The results show that, for short distances (

The environmental impact of timber production from poplar plantation was evaluated by means of Life Cycle Assessment (LCA) using an attributional approach. A comparison was performed between a baseline scenario and an alternative one in which different harvesting operations were identified. An economic allocation was adopted to solve the multi-functionality of the studied process, by taking into account the price of the main product and of co-products. Sensitivity analysis was performed on alternative mass allocation and yield variations that derive from using high sustainability plants or from climate stress. A different characterization method was also analyzed. Among the different field operations, crop management involves a higher impact respect to field preparation-planting and harvesting-soil restoring. Emissions related to fertilizers' applications are the main responsible for acidification, eutrophications and particular matter formation. The results show that the modelling of the environmental impact of timber production is robust. The alternative scenario resulted better than baseline for all impact categories (impact reduction ranging from 0.1% to 12.4%), except for HT-noc (+12.2%) and POF (+20.6%), due to fuel and oil consumption in the chainsaw used for harvesting. In the next years, introducing high-sustainability clones (characterized by higher yield and higher resistance to pests and drought) could be an effective way for reducing the environmental impact of poplar roundwood production.

Abstract Biogas production is mainly based on the anaerobic digestion of cereals silages and maize silage is the most utilized. Regarding biogas production, the most important portion of the plant is the ear. The corn ear, due to high starch content, is characterized by a higher biogas production compared to the silage of the whole plant. In this paper, we present the results of experimental field tests carried out in Northern Italy that aim to evaluate the anaerobic methane potential (BMP) of different portions of ensiled maize hybrids. The BMP production is evaluated considering the possibility of harvesting and ensiling: the whole plant; the plant cut at 75 cm of height; the ear only; the plant without the ear. For the different solutions, the results are reported as specific BMP and as average biogas production achievable per hectare. The methane production by harvesting and ensiling the whole plant (10,212 and 10,605 m3 ha−1, for maize class 600 and 700, respectively) is higher than the ones achievable by the other plant portions (7961 and 7707 m3 ha−1, from the ear; 9523 and 9784 m3 ha−1, from the plant cut at 75 cm; 3328 and 3554 m3 ha−1, from the plant without the ear, for maize class 600 and 700, respectively). The harvest of the whole plant, although it is the most productive solution, could not be the best solution under an economic and environmental point of view. Harvesting only the ear can be interesting considering the new Italian subsidy framework and for the biogas plants fed by biomass transported over long distances.

Abstract This study aims to evaluate the environmental consequences and energy requirements of a biogas production system and its further conversion into bioenergy by means of the Life Cycle Assessment (LCA) methodology. To do so, an Italian biogas plant operating with pig slurry and two energy crops (maize and triticale silages) as feedstock was assessed in detail in order to identify the environmental hotspots. The environmental profile was estimated through six impact categories: abiotic depletion potential (ADP), acidification potential (AP), eutrophication potential (EP), global warming potential (GWP), ozone layer depletion potential (ODP) and photochemical oxidation potential (POFP). An energy analysis related to the cumulative non-renewable fossil and nuclear energy demand (CED) was also performed, considering this indicator as an additional impact category. According to the results, the biomass production subsystem was identified as the main environmental key issue in terms of ADP, AP, EP, ODP and CED, with contributions ranging from 26% to 61% of the total impact. Regarding ADP, ODP and CED, these results are mainly related with diesel requirements in agricultural machinery, derived combustion emissions and mineral fertilizers production. Concerning AP and EP the production field emissions derived from fertilizers application was observed as the main contributor. Concerning GWP, this step presents an environmental credit due to the uptake of CO2 during crop growth, which contributes to offset the GHG emissions. The bioenergy production plant significantly contributes to the environmental impact in categories such as GWP (43%) and POFP (59%), mostly related with emissions produced in the gas engine and biogas losses. Emissions derived from digestate storage contribute to AP (52%) and EP (41%). The use of the digestate as an organic fertilizer has a beneficial role because this action avoids the production and use of mineral fertilizers. A sensitivity analysis was also conducted to assess the influence of variations in important parameters of biogas systems. The environmental profile of the biogas system turned out to be highly dependent on the selection of system boundaries and the allocation method. To sum up, this study aims to assess the environmental performance of a biogas technology available not only in Italy but also in other European countries. The environmental analysis of the process under study highlights the environmental benefits of the co-digestion processes, which not only produces biofuel but also reduces the disposal of solid wastes and produces digestate, with special value in the fertilization of agricultural soil.

Reducing methane (CH4) is a key objective to address climate change quickly. Manure management and storage play a significant role. In this context, a real-scale trial was performed to measure the ability of the commercial additive SOP LAGOON to reduce carbon-based greenhouse gas (GHG) emissions from liquid manure over approximately 4 months. Gas emissions were measured at a commercial dairy farm from two slurry tanks, one treated with the abovementioned product (SL) and the other used as the untreated control (UNT). After 3 and 4 months from the first additive applications, the SL storage tank showed lower and statistically significantly different emissions concerning the UNT (up to −80% for CH4 and −75% for CO2, p < 0.001), confirming and showing improved results from those reported in the previous small-scale works. The pH of the UNT tank was lower than that of the SL on two dates, while the other chemical characteristics of the slurry were not affected. In this work, SOP LAGOON proved to be an effective additive to help the farmers mitigate the contribution of stored liquid manure to global CH4 emissions, potentially improving the overall sustainability of the dairy industry.

Abstract In this study the environmental performances of the two most widespread cropping systems for cereal silage production in Northern Italy were analysed. Three different technical solutions for the seedbed preparation (conventional tillage, minimum tillage, and no tillage) were considered too. The Life Cycle Assessment method was chosen for the environmental analysis. The following impact potentials were evaluated: abiotic depletion, climate change, ozone depletion, acidification, eutrophication, and photochemical oxidant formation. One ton of dry matter was chosen as the functional unit. Taking into account that the functional unit selection can affect the environmental results, a sensitivity analysis was performed considering three other different functional units (area, biomethane production, and nutritive value). For both the crop systems, the emissions due to fertiliser application, diesel fuel consumption and production are the hotspots process with the greater influences on the overall environmental burden. Compared to single crop, the double crop system shows the worst environmental performance for all the evaluated impact categories except for euthrophication and acidification (−21% and −14%, respectively). Among the different technical solutions for seedbed preparations, the minimum tillage and the sod seeding achieve better results than the conventional tillage. For impact categories such as abiotic depletion, photochemical oxidation, climate change and ozone layer depletion there are impact reductions ranging from −2.5% to −11.5% for single crop and from −9.4% to −11.7% for double crop. For acidification and eutrophication the impact reduction is minimal for single crop while, for minimum tillage in double crops a slight increase is observed.

The production of plastic materials in the mid-20th century brought about transformative changes in consumer goods manufacturing and societal norms. However, this advancement paralleled an alarming surge in plastic pollution, driven by unrestrained consumption. This study focuses on the non-homogeneous and non-recyclable plastic waste (also known as plasmix in the Italian waste management), a residual blend resulting from plastic recycling processes. The main goals are to conduct an in-depth study of the plasmix landscape, to identify integration challenges, and to create a sustainable business model for broader adoption. Additionally, we aim to use life cycle assessment to examine the environmental effects of semi-finished plasmix-based materials that can be used to produce different products. This integrated approach ensures a holistic understanding of plasmix recycling, promoting both economic and environmental sustainability. The study contributes to sustainable waste management practices by offering a strategic approach to transform a challenging waste stream into economic opportunities. By addressing the market viability of plasmix-based products through an empirically supported business model, the research underscores the significance of recycling in mitigating plastic pollution and advancing a circular economy.

Abstract Short Rotation Coppices (SRC) can be a suitable solution for the production of biomass, mainly due to the easy-to-harvest good-quality feedstock. Besides technical, social and economic aspects, environmental issues are important to be taken into account when developing SRC. Although some studies focused on environmental sustainability of SRC were carried out only few compare different arboreous species using primary data. In this study, the environmental evaluation of SRC plantations carried out with 14 poplar and 6 willow clones was performed using primary data collected during experimental field tests over 12 years. Twelve impact potentials were evaluated using the characterization factors reported by the ILCD method: climate change (CC), ozone depletion (OD), Human toxicity, cancer effects (HTc), Human toxicity, non-cancer effects (HT), particulate matter (PM), photochemical ozone formation (POF), acidification (TA), freshwater eutrophication (FE), terrestrial eutrophication (TE), marine eutrophication (ME), freshwater ecotoxicity (FEx) and mineral, fossil and renewable resource depletion (MFRD). Both for poplar and for willow, among the different clones the environmental performance greatly vary mainly due to the yield. The choice of the most productive clones involves a reduction of the environmental impact of the produced biomass of about 35% (respect to the average results both for poplar and willow). However, biofuel production from willow SRC achieves lower environmental burdens respect to poplar SRC considering both the average biomass yield and the most productive clones.