• Energy Research

ABSTRACTThis study investigates climate change impacts on spontaneous vegetation, focusing on the Mediterranean basin, a hotspot for climatic changes. Two case study areas, Monti Sibillini (central Italy, temperate) and Sidi Makhlouf (Southern Tunisia, arid), were selected for their contrasting climates and vegetation. Using WorldClim's CMCC‐ESM2 climate model, future vegetation distribution was predicted for 2050 and 2080 under SSP 245 (optimistic) and 585 (pessimistic) scenarios. Two spectral indices, NDVI (temperate area) and SAVI (arid area), served as vegetation proxies, classified into three classes using K‐means (NDVI: high = mainly associated with woodlands, medium = shrublands, continuous grasslands and crops, low = discontinuous grasslands, bare soil, and rocks; SAVI: high = mainly associated with woods, olive trees, and crops, medium = shrublands and sparse olive trees, low = bare soil and saline areas). Classes validated with ESA WorldCover 2020 data and sampled via 1390 presence‐only points. A set of 33 environmental variables (topography, soil, and bioclimatic) was screened using Pearson correlation matrices, and predictive models were built using four algorithms: MaxEnt, Random Forest, XG Boost, and Neural Network. Results revealed increasing temperatures and declining precipitation in both regions, confirming Mediterranean climate trends. Vegetation changes varied by area: in the temperate area, woodlands and shrublands were stable, but discontinuous grasslands expanded. In the arid area, woodlands gained suitable habitat, while bare soil declined under the pessimistic SSP 585 scenario. Both areas showed an upward shift for shrublands and grasslands. The models indicated significant shifts in areal distribution and environmental conditions, affecting habitat suitability and ecosystem dynamics. MaxEnt emerged as the most reliable algorithm for small presence‐only datasets, effectively predicting habitat suitability. The findings highlight significant vegetation redistribution and altered ecosystem dynamics due to climate change, underscoring the importance of these models in planning for future ecological challenges.

Biomass production helps address the worldwide energy demand. However, some controversial issues have been identified such as the possible conflict between the goal of increasing vegetable biomass and food production and the need to limit environmental impacts. In Mediterranean region, where the supply of some natural resources appears significantly limited (e.g., water) and the competition for land is higher than it was in the past, the objective of evaluating environmental burdens at a regional scale represents an important issue, especially if the assessment considers the farmer scope of increasing productivity. Using a Life Cycle Assessment (LCA) "from cradle to field gate" approach, this paper aims to evaluate land-based environmental sustainability related to four energy crop options. We carried out a LCA differentiating between annual and perennial species and between irrigated (giant reed and sorghum) and rainfed crops (cardoon and milk thistle) to determine their performances and impacts within the same context. The findings suggest that irrigated crops generate larger impacts on the environment than rainfed species and that annual crops (both irrigated and rainfed) are more damaging than the respective perennial crops. The damages were expressed in Ecopoints, where one Ecopoint corresponds to one thousandth of the annual overall environmental burden of an average European inhabitant. Ecopoints for sorghum, giant reed, milk thistle and cardoon are equal to 361, 288, 146, and 138, respectively. Except for irrigation, fertilizers were found to be the input with the largest effect, accounting for 37% (giant reed) to 75% (cardoon) of the environmental burden on the system. The results do not suggest the presence of a winning crop option - i.e., a crop that shows the best environmental performances everywhere and in all categories - since regional environmental burdens are simultaneously related to different factors (e.g., land allocation, crop productivity, and degree of practice intensification) that drive farmer choice. Finally, following a dynamic and innovative perspective, we evaluated the trade-off between productivity and environmental burden for each crop simulating an increasing product variation. We found that environmental burdens would increase more proportionally than crop yields done. Especially the latter finding provides interesting suggestions on energy cropping system integration within agricultural planning under stressed natural resource conditions.

The photovoltaic (PV) greenhouses are closed agrivoltaic (CA) systems that allow the production of energy and food on the same land, but may result in a yield reduction when the shading of the PV panels is excessive. Adopting innovative cropping systems can increase the yield of the CA area, generating a more productive and sustainable agrosystem. In this case study we quantified the increase of land productivity derived from the integration of an experimental vertical farm (VF) for baby leaf lettuce inside a pre-existing commercial CA. The mixed system increased the yield by 13 times compared to the CA and the average LER was 1.31, but only 12 % of the energy consumption was covered by the CA energy. To achieve the energy self-sufficiency and avoid the related CO2 emissions, the VF area should not exceed 7-18 % of the CA area, depending on the PV energy yield and the daily light integral (DLI) of the LED lighting, meaning a land consumption from 5 to 14 times higher than the VF area. The support of the PV energy was essential for the profitability of the VFCA. Design features and solutions were proposed to increase the agronomic and economic sustainability of the VFCA. The VFs can be considered a possible answer for the reconversion of the actual underutilized CAs with high PV cover ratios into productive and efficient cropping systems, but a trade-off between energy production and land consumption should be identified to ensure an acceptable environmental sustainability of the mixed system.

The energy consumption of sheep milk cooling systems (MCSs) was quantified in this study to provide original information filling a literature gap on the impact of sheep milk cooling on the energy and economic balance in dairy farms. Performance and energy monitoring tests were conducted simultaneously on 22 MCSs in Sardinia (Italy). The results determined the cooling time as a function of the performance class and number of milkings. The Energy Utilization Index (EUI) was applied to measure the energy required to cool down the milk and estimate the incidence on its price. The average EUI was 1.76 kWh 100 L−1 for two-milkings and 2.43 kWh 100 L−1 for four-milkings MCSs, whereas the CO2 emissions ranged from 998 to 1378 g CO2 100 L−1 for two- and four-milkings MCSs, respectively. The estimated energy consumption for the storage of refrigerated sheep milk was 0.12 kWh 100 L−1. The malfunctioning MCSs averagely consumed 31% more energy than regular systems. The energy cost for cooling accounted for 0.61% on the current sheep milk price in Italy. Based on the analysis, the reported EUI values can be used as a preliminary indicator of the regular operation of MCSs.

The oilseed rape conventional system can be moved to a more sustainable one by reducing herbicide application whilst ensuring at the same time effective weed control, maintaining oilseed rape yield, and quality and increasing profitability. Over three growing season periods, two field experiments at two different Southern Italy locations were carried out. In both sites, a conventional weed-control management system (recommended label dose), four alternative low-herbicide treatments, and an untreated control were compared. We monitored weeds and crop response to herbicide treatments, and calculated the net economic return, within site and year, for each treatment. In experiment 1, a half dose of herbicide did not show any significant difference in seed yield with respect to conventional treatment in two of three growing seasons. In experiment 2, compared with the conventional system, weedy control and the lowest applied herbicide dose treatment (25% of the recommended label dose) did not underline significant differences with regard to yield level. Net returns from the half dose of metazachlor herbicide were not significantly lower than net returns from conventional treatment in experiment 1 (on a three-year average 748 vs. 812 € ha−1, respectively). Our findings suggest that the herbicide dose might be cut by at least 50% in order not to jeopardize negative effects on production and economic performances.

Abstract The development of biogas production exacerbated the competition for land availability between crops dedicated to human consumption and those intended for energy production. Residual biomasses have been often proposed for their positive outcomes in terms of reduced pressure on land use. However, literature did not assess optimization options for existing biogas plants feeding. This paper developed a bio-economic model for the optimization of agricultural biogas supply chains using artichoke byproducts in existing plants. A multiple goal linear programming approach was adopted, using two objective functions, calculating respectively net present value and land use from energy crops, associated to a regional biogas network. Three scenarios were defined using primary and secondary data on the residues of a specific artichoke variety - globe - and an Italian region - Sardinia. In the Business As Usual scenario, net present value is about 7 million € with a land use of about 2720 ha. When using artichoke residues, the economic impact increases by 28% and land use is reduced by 83% if net present value is optimized. When land use is optimized, the economic impact still grows by 25% and land use is reduced by 100%. Results from this study confirm that, under certain conditions, locally available residual biomasses can replace energy crops in existing biogas networks, coupling viability and sustainability.

The paper aims at evaluating the potential biogas production, both in terms of CH4 and theoretical energy potential, from globe artichoke agricultural byproducts in Sardinia. Field data about the productivity of byproducts were collected on five artichoke varieties cultivated in Sardinia, to assess the biomethane production of their aboveground non-food parts (excluding the head). Moreover, secondary data from previous studies and surveys at regional scale were collected to evaluate the potential biogas production of the different districts. Fresh globe artichoke residues yielded, on average, 292.2 Nm3·tDOM−1, with dissimilarities among cultivars. Fresh samples were analyzed in two series: (a) wet basis; and (b) wet basis with catalytic enzymes application. Enzymes proved to have some beneficial effects in terms of anticipated biomethane availability. At the regional level, ab. 20 × 106 Nm3 CH4 could be produced, corresponding to the 60% of current installed capacity. However, districts potentials show some differences, depending on the specific biomass partitioning and on the productivity of cultivated varieties. Regional assessments should encompass the sensitiveness of results to agro-economic variables and the economic impacts of globe artichoke residue use in the current regional biogas sector.