• Energy Research

Soils contamination give rise to one of many environmental problems, such as heavy metals pollutant that reduces resources, leading to serious health problems for humans directly or indirectly, by the contamination of the food crops. Moreover, the cultivation of industrial crops in heavy metals contaminated land improves several ecosystem services, such as biodiversity maintenance and nutrient and water cycling, while promoting soil decontamination through a phytoremediation technique. This biological technique uses plants to remediate the contaminated land while generating economic value in land that used to be unproductivity. This technique synergizes with the European Green Deal's focus on environmental restoration, biodiversity conservation, and the transition towards a sustainable and resilient future. Biogas serves as a renewable energy source, reducing greenhouse gas emissions and dependence on fossil fuels. Simultaneously, phytoremediation harnesses the power of plants to mitigate pollution and restore ecosystems. Together, these practices contribute to the overarching goals of the European Green Deal, driving the continent towards a more environmentally conscious and prosperous future. This work aimed to evaluate the tolerance of giant reed in soils contaminated by two heavy metals (Pb and Cd). The biomass produced was tested as a substrate in anaerobic digestion to produce biomethane. Giant reed showed its great ability to growth in heavy metals polluted soils, even if the presence of cadmium in the soils, and in the plants reduced the productivity of giant reed and the biomethane yield. Proceedings of the 31st European Biomass Conference and Exhibition, 5-8 June 2023, Bologna, Italy, pp. 748-751

Castor (Ricinus communis L.) is an oilseed species, which in southern Italy is cultivated as annual during the spring-summer period under irrigation, but in most temperate areas such as those of eastern coast of Sicily, it could be grown as semiperennial with no irrigation, by the adoption of autumnal sowings. A field experiment was conducted in southeastern Sicily with the aim of assessing plant surviving, seed yield and oil quality of four castor genotypes originating from different geographical areas (two Sicilian, one Tunisian and one Brazilian). The favorable climatic conditions allowed the plant to survive during the fall-winter period. Seed yield reached 3.45 t ha-1 on average of the two years and seed oil content ranged from 45% (Tunisian cultivar) to 48% ('Local RG 2' Sicilian genotype). Oil yield reflected the variation in seed yield. Genetic diversity for fatty acid composition and saponification number, iodine value and cetane number was evidenced. When ricinoleic acid is not taken into account, the oil of all genotypes satisfied the E.U. standards for biodiesel. The ricinoleic acid was the lowest (79%) in the Sicilian 'Local RG 2' and the highest (89%) in the Tunisian one, revealing a greater suitability of oil of the first genotype for biodiesel. In turn, the oil of Tunisian genotype could be exploited in other bio-based industrial sectors. The study also demonstrated that in the southeastern coast of Sicily autumnal sowings might be advantageous for castor grown as semi-perennial crop, mainly since they allow saving irrigation water.

In Mediterranean environments, few perennial grass species are available for cultivation in rainfed systems and marginal lands, where plants with excellent adaptation are required. The aim of the present work was to determine the potentiality of five native Mediterranean perennial grasses for lignocellulosic biomass production. Wild accessions of three hemicryptophytes (Ampelodesmos mauritanicus, Hyparrhenia hirta, and Piptatherum miliaceum) and two geophytes (Saccharum spontaneum ssp. aegyptiacum and Sorghum halepense) were collected at three Mediterranean sites (Sicily, Sardinia and Majorca), and their morphological, physiological, productivity and quality traits were evaluated in the field. The species differed in height, with S. spontaneum and A. mauritanicus being the tallest. The leaf mass ratio ranged from 0.23 to 1.0 g g -1 among species. Maximum net photosynthesis was measured in the C 4 species S. spontaneum and S.halepense (26.6 and 23.8 mmol CO 2 m -2 s -1 , respectively). A. mauritanicus showed the lowest transpiration rate and the highest instantaneous water use efficiency (2.7 mmol H 2 O m -2 s -1 and 6.9 mmol CO 2 mmol H 2 O -1 , respectively). S. spontaneum was the most productive species, yielding more than 18 Mg DM ha -1 as a three-year average. The highest content of acid detergent lignin was found in P. miliaceum, while A. mauritanicus was the species richest in hemicellulose and cellulose and poorest in ash. S. spontaneum showed the highest moisture content at harvest. Overall, the studied species showed interesting morphological, physiological, productive and qualitative traits. Nevertheless, additional research is necessary to investigate their long-term performance under different management strategies.

Low-ILUC risk feedstock requires genotype selection with climate change and abiotic stress resilient traits to cope unsuitable sites for food crops. Giant reed is a C3 warm-season perennial energy grass that has received great attention for drought prone areas of southern Europe. Although phenotypic variability exists in giant reed, the restricted genetic diversity, inability to produce viable seeds and highly polyploidy of this species basically precludes breeding effort. This study compared 12 giant reed clones obtained at the University of Bologna (Italy) from mutagenesis .-irradiation of in vitro cell cultures. Preliminary observations at the University of Bologna identified a subset of 12 mutant clones with positive alterations in shoot morphology and architecture (increased plant height, higher number of stems per plots, erect habitus) when compared with giant reed wild type. To this end, twelve mutant clones were selected and compared side-by-side in fiend, in a semiarid environment in southern Italy (University of Catania, Italy) for yield and morphology. First year results of biomass yield and morphology under non-limiting water conditions are reported here, and compared with a local clone of giant reed grown in a complementary field experiment aside. Proceedings of the 30th European Biomass Conference and Exhibition, 9-12 May 2022, Online, pp. 125-128

This review describes the multiple utilization of perennial grasses as resilient crops for a multifunctional agriculture. Beyond its role of producing food, feed and fiber, the concept of multifunctional agriculture includes many other functions, such as ecosystem services, renewable energy production and a contribution to the socio-economic viability of rural areas. Traditionally used for feed, some perennial grasses—known as perennial energy grasses (e.g., miscanthus—Miscanthus × giganteus Greef et Deuter, giant reed—Arundo donax L., switchgrass—Panicun virgatum L., reed canary grass—Phalaris arundinacea L.)—have been recommended as a biomass source for both energy and non-energy applications, and ecosystem services. Perennial grasses are lignocellulosic, low-cost feedstock, able to grow in variable environments including marginal lands. Due to their high yield, resilient traits, biomass composition, energy and environmental sustainability, perennial grasses are a candidate feedstock to foster the bio-based economy and adapt to a changing agriculture. However, perennial grasses for biomass production are largely undomesticated crops, or are at early stages of development. Hence, a great potential for improvements is expected, provided that research on breeding, agronomy, post-harvest logistic and bioconversion is undertaken in order to deliver resilient genotypes growing and performing well across a broad range of environmental conditions, climatic uncertainty, marginal land type and end-use destinations.

The main objective of the present study was to assess the biomass dry matter yield (DM), the water use efficiency (WUE), the energy content (EC) and the energy return on investment (EROI) at the farm gate of several perennial grasses grown at the experimental farm of the University of Catania, Italy. Field trials of Arundo donax, Miscanthus x giganteus, Saccharum spontaneum spp. aegyptiacum, Sorghum halepense, Oryzopsis miliacea and Cymbopogon hirthus grown under low-input practices in an autumn and a winter harvesting regime were used. From February 2014 to February 2015 (winter harvest regime), and from October 2014 to October 2015 (autumn harvest regime), the dryness index (P/ET) was computed. Main results suggested that Saccharum was the outstanding species. Across species there was no difference in DM between autumn and winter harvests. On the other hand, WUE was higher in autumn than winter harvest, due to the lower dryness index in the autumn (0.32) than in the winter regime (0.53). The EC, although significantly different, was in the range of 1.0 MJ kg-1 between the most (Miscanthus, 15.9 MJ kg-1) and the least (Oryzopsis, 14.9 MJ kg-1) species. All species can be considered sustainable from the energy point of view as the EROI ranged from 120:1 in Saccharum to 20:1 in Cymbopogon. Proceedings of the 27th European Biomass Conference and Exhibition, 27-30 May 2019, Lisbon, Portugal, pp. 226-230

According to the RED II (2018/2001/EU), Member States must supply a minimum of 14% of the energy consumed in road and rail transport by 2030, of which the contribution of advanced biofuels and biogas must reach at least 3.5%. Reduce biomass recalcitrance of high-yielding lignocellulosic crops by means of agronomic strategies would significantly contribute to the advanced biofuel production goal. Lignocellulose is the lowest cost raw material on earth, it is a no-food biomass and its use alone or in mix with other biomasses can strongly increase the biomass availability for advanced biomethane production. The present study evaluated the suitability of the lignocellulosic, herbaceous Arundo donax as a biomass feedstock for advanced biomethane production. Harvest time and nitrogen fertilization treatments were adopted to reduce biomass recalcitrance thereby increasing biomethane yield. Biochemical Methane Potential (BMP) was evaluated on batch anaerobic fermenters in mesophilic conditions. The BMP at 30 days of incubation was influenced by the investigated treatments, the incubation time and the interaction of these two factors. The trend showed a lag phase for the first 5 days of testing, due probably to the adaptation of the bacterial flora to the lignocellulosic matrix, followed by an exponential increase up to approximately 18 days; after that a slight increase tending to an asymptotic trend in the final phase (up to day 30) was observed. The highest BMP was reached by the combination of winter harvest (W) and 80 kg N ha-1 (123.4 Nml CH4 g-1 SV), followed by the autumn harvest (A) and 80 kg N ha-1 (118.1 Nml CH4 g-1 SV). The unfertilized treatments showed an opposite BMP, with the autumn higher than winter harvest (106.2 and 100.3 Nml CH4 g-1 SV, respectively). In terms of biomethane yield per unit land area, WN80 showed the highest (1717 ± 203 m3 CH4 ha-1) and WN0 the lowest (859 ± 93 m3 CH4 ha-1). Nitrogen fertilization looks a promising strategy to reduce biomass recalcitrance for bioconversion by anaerobic digestion mainly due to the higher content of neutral detergent soluble and protein; however, it should be proved by an energy, economic and environmental analysis to ascertain an overall sustainability. Proceedings of the 28th European Biomass Conference and Exhibition, 6-9 July 2020, Virtual, pp. 222-227

The Joint Research Center (JRC) has set a series of thresholds to define marginal lands in terms of biophysical constraints. We focus on climate limitation given by the ratio between precipitations and potential evapotranspiration (P/PET). Indeed, the Mediterranean climates are characterized by long drought periods during summer, with low rainfall and high evapotranspiration, what limits plant CO2 assimilation and biomass production, particularly of spring-summer crops. The present study ascertained the potential and actual yield of African fodder cane (Saccharum spontaneum ssp. aegypticum), a perennial, herbaceous, rhizomatous perennial grass, native from North Africa and widespread in South Mediterranean regions. Saccharum was grown under different water regimes (I0 - rainfed, I50 – 50% ETm and I100 – 100% ETm restoration) for six successive growing seasons, namely from the 7th to the 12th. Throughout the experimental period, the dryness index greatly changed among the six growing seasons: three out of the six (2012, 2013 and 2014) were much lower than the threshold of 0.6 set in the JRC report, indicating severe drought seasons, two were quite similar to the threshold value (2015 and 2016), while the 2011, which was the wettest season overall, had a dryness index higher than the threshold. Actual biomass yield was mostly driven by meteorological conditions through the growing seasons. However, even in the driest seasons, Saccharum was able to maintain satisfactory biomass yield and good yield persistence. As compared to the potential yield (I100), the relative yield reduction over the six years was in the range of 31% in the most stress condition (I0), but the energy productivity and the water footprint improved by 62% and 32%, respectively, indicating a higher sustainability of the cropping system when irrigation water was not provided. When the irrigation level was raised to the 50% of the maximum evapotranspiration restoration (ETm), the relative yield, over the six growing seasons, reduced by 16.5%; the energy productivity and the water footprint improved of only 14 and 22%, respectively. This study underlines the importance for strategic selection of crops for a given environmental condition dominated by a specific biophysical constraint and the agronomic practices leading to increase the energy productivity while reducing the pressure on Mediterranean freshwater. Proceedings of the 28th European Biomass Conference and Exhibition, 6-9 July 2020, Virtual, pp. 34-40