The world's most developed countries and the European Union (EU) deem that the renewable energy sources should partly substitute fossil fuels and become a "bridge" to the utilization of other energy sources of the future. This paper will present the possibility of using pruned biomass from fruit cultivars. It will also present the calculation of potential energy from the mentioned raw materials in order to determine the extent of replacement of non-renewable sources with these types of renewable energy. One of the results of the intensive fruit-growing process, in post pruning stage, is large amount of pruned biomass waste. Based on the calculated biomass (kg ha -1 ) from intensively grown woody fruit crops that are most grown in Croatia (apple, pear, apricots, peach and nectarine, sweet cherry, sour cherry, prune, walnut, hazelnut, almond, fig, grapevine, and olive) and the analysis of combustible (carbon 45.55-49.28%, hydrogen 5.91-6.83%, and sulphur 0.18-0.21%) and non-combustible matters (oxygen 43.34-46.6%, nitrogen 0.54-1.05%, moisture 3.65-8.83%, ashes 1.52-5.39%) with impact of lowering the biomass heating value (15.602-17.727 MJ kg -1 ), the energy potential of the pruned fruit biomass is calculated at 4.21 PJ.Additional key words: bioenergy; heating values; olive groves; orchards; renewable energy sources; vineyards. Resumen Potencial energético de la biomasa procedente de árboles frutales podados en CroaciaLos principales países desarrollados del mundo y de la Unión Europea (UE) consideran que las fuentes de energía renovables deberían sustituir parcialmente a los combustibles fósiles y convertirse en el futuro en un "puente" hacia la utilización de otras fuentes de energía. En este trabajo, se planteó la posibilidad de utilizar biomasa cortada procedente de cultivos frutales con el propósito de calcular el potencial energético del mencionado material en bruto, así como determinar el grado de remplazo de fuentes no renovables con este tipo de fuentes de energía renovable. Uno de los resultados del proceso de cultivo de frutales en intensivo, tras la época de poda, es la gran cantidad de biomasa cortada inútil. En base al cálculo de biomasa (kg ha -1 ) de los frutales leñosos de cultivo intensivo más comunes en el territorio de Croacia (manzano, peral, albaricoquero, melocotonero y nectarino, cerezo, guindo, ciruelo, nogal, avellano, almendro, higuera, viña y olivo) y en base al análisis de partículas combustibles (carbono 45,55-49,28%, hidrógeno 5,91-6,83% y azufre 0,18-0,21%) y de partículas no combustibles (oxígeno 43,34-46,6%, nitrógeno 0,54-1,05%, vapor de agua 3,65-8,83% y cenizas 1,52-5,39%) que influyen en el poder calorífico inferior de la biomasa (15, ), se calcula que la energía potencial de los restos de poda de frutales es 4.21 PJ.

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Miscanthus, a C4 perennial rhizomatous grass from Asia is a leading candidate for the supply of sustainable biomass needed to grow the bioeconomy. European Miscanthus breeding programmes have recently produced a new range of seeded hybrids with the objective of increasing scalability to large acreages limited by current clonal propagation. For the EU-GRACE project new replicated field trials were established in seven locations across Europe in 2018 with eight intraspecific M. sinensis hybrids (sin×sin) and six M. sacchariflorus × M. sinensis (sac×sin) from Dutch and UK breeding programmes respectively with clonal Miscanthus × giganteus. The planting density of the sin×sin was double that of sac×sin (30,000 & 15,000 plants ha -1 ), creating commercially relevant upscaling comparisons between systems. Over the first three years, the establishment depended on location and hybrid. The mature sin×sin hybrids formed tight tufts of shoots up to 2.5 m tall which flower and senesce earlier than the taller sac×sin hybrids. Following the third growing season, the highest yields were recorded in Northern Italy at a low altitude (average 13.7 (max 21) Mg DM ha -1 ) and the lowest yielding was on the industrially damaged marginal land site in Northern France (average 7.0 (max 10) Mg DM ha -1 ). Moisture contents at spring harvest were lowest in Croatia (21.7%) and highest in Wales, UK (41.6%). Overall, lower moisture contents at harvest, which are highly desirable for transport, storage and for most end-use applications, were found in sin×sin hybrids than sac×sin (30 and 40% respectively). Yield depended on climate interactions with the hybrid and their associated planting systems. The sin×sin hybrids appeared better adapted to northern Europe and sac×sin hybrids to southern Europe. Longer-term yield observations over crop lifespans will be needed to explore the biological (yield persistence) and economic costs and benefits of the different hybrid systems.

Miscanthus, a C4 perennial rhizomatous grass, is capable of growing in varied climates and soil types in Europe, including on marginal lands. It can produce high yields with low nutrient inputs when harvested after complete senescence. Senescence induction and rate depend on complex genetic, environmental, and management interactions. To explore these interactions, we analysed four miscanthus hybrids (two novel seed‐based hybrids, GRC 3 [Miscanthus sinensis × sinensis] and GRC 14 [M. sacchariflorus × sinensis]; GRC 15, a novel M. sacchariflorus × sinensis clone; and GRC 9, a standard Miscanthus × giganteus clone) in Italy, Croatia, Germany and the UK. Over all trial locations and hybrids, the average aboveground biomass of the 3‐year‐old stands in August 2020 was 15 t DM ha−1 with nutrient contents of 7.6 mg N g−1 and 14.6 mg K g−1. As expected, delaying the harvest until spring reduced overall yield and nutrient contents (12 t DM ha−1, 3.3 mg N g−1, and 5.5 mg K g−1). At lower latitudes, the late‐ripening M. sacchariflorus × sinensis GRC 14 and GRC 15 combined high yields with low nutrient contents. At the most elevated latitude location (UK), the early‐ripening M. sinensis × sinensis combined high biomass yields with low nutrient offtakes. The clonal Miscanthus × giganteus with intermediate flowering and senescence attained similar low nutrient contents by spring harvest at all four locations. Seasonal changes in yield and nutrient levels analysed in this study provide: (1) a first step towards recommending hybrids for specific locations and end uses in Europe; (2) crucial data for determination of harvest time and practical steps in the valorization of biomass; and (3) key sustainability data for life cycle assessments. Identification of trade‐offs resulting from genetic × environment × management interactions is critical for increasing sustainable biomass supply from miscanthus grown on marginal lands.

The potential of energy crops Sida hermaphrodita on organic farm'.A b s t r a c t. In the context of the growing demand for biomass, which is being encouraged by the EU directives on the promotion of the use of renewable energy, recent investigations have been increasingly focused on fast-growing energy crops. The aim of this study was to investigate the energy properties of three types of agricultural energy crops: Arundo donax L., Miscanthus × giganteus and Sida hermaphrodita. This investigation looked into the content of non-combustible and combustible matter, higher and lower heating values, lignocellulose content, and biomass macro-elements. The results indicate that the energy values of these crops are comparable, while their lignocellulose content shows significant variations. Thus, Arundo donax L. can best be utilised as solid biofuel due to its highest lignin content, while Miscanthus × giganteus and Sida hermaphrodita L. can be used for both liquid and solid biofuels production. As far as Arundo donax L. is concerned, a higher ash level should be taken into consideration.K e y w o r d s : energy crops, energy values, chemical composition

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SummaryAlthough biomass of Miscanthus x giganteus shows a significant potential for production of second-generation biofuels, it is currently mostly used as a combustion fuel. The objective of this paper is to investigate: (I) dry matter yield and yield components; (II) biomass composition; and (III) potential divergences of the investigated parameters from the standard for solid fuels CEN/TS 14961:2005, in relation to two harvest seasons and six fertilizer treatments. The investigation has determined that there is a potential for producing significant quantity of biomass from M x giganteus in the investigated agro-ecological conditions of the mountain areas of Croatia. The laboratory analyses indicated the suitability of using biomass in direct combustion.