• Energy Research

Bioenergy is being increasingly used worldwide to generate energy from biogas, biomethane, and other biofuels, bringing significant environmental and economic benefits. In Italy, biogas can significantly contribute to the achievement of the renewable energy targets set at the national and European levels. The exploitation of this energy source in a particular area is determined by its environmental and anthropic properties, as well as by the incentive system and the political will of decision makers. This paper analyzes the socioeconomic drivers and natural conditions triggering bioelectricity production in Italian regions. The analysis proposed here was performed in two steps—first, by identifying groups of similar regions for some natural, social, and economic variables, and then by modeling the historical trajectory of bioelectricity production for each identified group with innovation diffusion models. As a general finding, regions pertaining to the same group in terms of natural and socioeconomic conditions revealed a similar production pattern for bioelectricity, as confirmed by the results of diffusion modeling. On the basis of the diffusion modeling procedure, some scenario simulations were performed, which suggested the set-up of suitable policy actions for each group of regions.

This paper aims to provide a bibliometric analysis of publication trends on the themes of biomass and bioenergy worldwide. A wide range of studies have been performed in the field of the usage of biomass for energy production, in order to contribute to the green transition from fossil fuels to renewable energies. Over the past 20 years (from 2000 to 2019), approximately 10,000 articles have been published in the “Agricultural and Biological Sciences” field on this theme, covering all stages of production—from the harvesting of crops to the particular type of energy produced. Articles were obtained from the SCOPUS database and examined with a text mining tool in order to analyze publication trends over the last two decades. Publications per year in the bioenergy theme have grown from 91 in 2000 to 773 in 2019. In particular the analyses showed how environmental aspects have increased their importance (from 7.3% to 11.8%), along with studies related to crop conditions (from 10.4% to 18.6%). Regarding the use of energy produced, growing trends were recognized for the impact of biofuels (mentions moved from 0.14 times per article in 2000 to 0.38 in 2019) and biogases (from 0.14 to 0.42 mentions). Environmental objectives have guided the interest of researchers, encouraging studies on biomass sources and the optimal use of the energy produced. This analysis aims to describe the research evolution, providing an analysis that can be helpful to predict future scenarios and participation among stakeholders in the sector.

Sustainable development and reducing natural and energy resource consumption are the focus of the policies of many institutions. In this context, livestock farming is one of the major anthropogenic sources of GHG and acidifying gas emissions and requires comprehensive analysis to minimise its ecological footprint. For this reason, it is beneficial to analyse the various processes within this production sector to reduce the consumption of resources, particularly water and soil consumption; reduce energy consumption; and try to valorise the biowaste produced, especially manure, byproducts and wastewater. Reusing residual bioresource and organic waste offers the possibility of valorising a discarded product and, at the same time, reducing the consumption of natural resources. For this purpose, biorefinery processes allow bioresources to be transformed into bioproducts or bioenergy. Therefore, this study investigates the application of biorefinery processes to animal-derived waste, aiming to extract valuable resources while curbing resource consumption. This review analysed 293 scientific papers on biorefinery processes published in the last 11 years applied to livestock biomass to extract relevant information to understand the evolution of this topic and formulate hypotheses regarding future research di- rections. The analysis strongly emphasizes energy production and a growing interest in insect cultivation. In the coming years, one of the most significant challenges will be the successful transfer of technologies and processes from experimental research to the applied industry. To do this, it will be necessary to reduce costs, exploit economies of scale, improve process management, and develop synergies between different industrial sectors to implement smart circular economy systems. Overall, this review aims to clarify the hypothesis driving research in this area and emphasizes the tangible applications of findings within the broader context of sustainable resource management.

The increasing demand of vegetal biomass for biogas production is causing competition with food production. To reduce this problem and to provide new opportunities it is necessary to take into consideration different kinds of vegetable biomass that are more sustainable. Grass from the maintenance of non-cultivated areas such as riverbanks has not yet been fully studied as a potential biomass for biogas production. Although grass has lower methane potential, it could be interesting because it does not compete with food production. However, there is a lack of appropriate technologies and working system adapted to these areas. In this paper, different systems that could be available for the mowing and harvesting of grass along riverbanks have been preliminarily assessed through the evaluation of the field capacity, labour requirement, economic and energy aspects. The splitting of the cutting and harvesting phases into operations with different machinery seems to be the best system for handling this biomass. However, these solutions have to take into consideration the presence of obstacles or accessibility problems in the harvesting areas that could limit the operational feasibility and subsequent correct sizing.

The growing interest in renewable energies requires increased consciousness regarding their impact on the territory and communities. For this reason, several researchers have studied the conditions that influence the balance between the benefits and costs of new bioenergy plants, producing a wide-ranging review of studies regarding the optimal location of plants. This process is based on several economic, social and environmental conditions. One of the most valuable and useful tools to evaluate the criteria and attribute the proper weight is the multicriteria decision model/analysis (MCDM/A). This review summarizes the studies of the last 20 years to describe the criteria that influence the location of bioenergy plants and how the authors compared and categorized the alternatives. In total, 40 papers were reviewed, studying i) the adopted criteria and multicriteria decision model/analysis and ii) the environmental and social conditions that influence this type of analysis. As a result, 55 criteria, divided into 13 subgroups and three main groups (social, economic, and environmental), are identified and studied. This research can support future studies that address the territorial management of energy sources and integrate different types of renewable energies.

Grass from landscape management or from agricultural practices is currently destined mainly for composting, with the production of a valuable product; however, this process demands energy. Anaerobic digestion, instead, represents an energy-positive process that results in the production of fuel, biogas, and a fertilizer, namely digestate. Previous tests for the evaluation of biogas yield from freshly harvested grass gave promising results. However, for a practical exploitation of this resource, appropriate conservation is necessary in order to enable the daily load of digesters while reducing the loss of organic matter. The present work is focused on the evaluation of biogas and methane yield from dried and ensiled grass (without conditioning) in order to assess eventual biogas potential losses in comparison to digested fresh grass. Tests were performed with grass collected from riverbanks (Veneto, Northern Italy) in batch, lab scale digesters. Dry and ensiled grass showed a good potential for exploitation in the anaerobic digestion process, reaching biogas yields of 565.9 and 573.4 NL∙kgVS−1, respectively. Compared to the biogas yield of 639.7 NL∙kgVS−1 of the fresh grass, the conservation treatment determined yield reductions of 11.5% and 10.4% for dried and ensiled grass, respectively. However, considering the methane yields, conservation treatments showed lower reductions, amounting to 4.8% for dry grass and 0.5% for ensiled grass; presumably the higher concentration of organic acids in ensiled grass determined a higher methane content in biogas and the consequently lower reduction of methane yield.