Biomass obtained from cultivated energy crops is one of the raw materials with the highest potential in renewable energy production. Although such biomass can be used in production of lignocellulose ...bioethanol, it is currently mostly used as solid fuel for generating heat and/or electric energy via combustion processes. Calorific values, proximate and ultimate analysis, cell structure and micro- and macro-elements data are considered as basic parameters in the valorization of fuel properties during biomass combustion processes. Energy crops are cultivated with the aim to produce the largest possible quantity of biomass with minimal agro-technical inputs. One of these crops is Sida hermaphrodita (L.) Rusby. Given the fact that the chemical composition of biomass is influenced by a number of agro-ecological and agro-technical factors, the aim of this work was to determine the fuel properties of Sida hermaphrodita biomass obtained from three different harvest seasons (autumn, winter and spring) and cultivated in the area of the Republic of Croatia. On the basis of these investigations it was possible to conclude that harvest delaying towards spring season had a positive impact on suitability of using biomass of Sida hermaphrodita in the combustion process, which primarily means significant lowering the contents of moisture (18.64%), ash (1.94%), and nitrogen (0.65%), but also means increasing the contents of fixed carbon (6.21%) and lignin (25.45%).
Pokus s različitim varijantama suzbijanja korova u usjevu kukuruza proveden je u 2021. godini na lokaciji pored naselja Markovo Polje na praškasto ilovastom tlu. Primijenjene su tri varijante ...suzbijanja korova: 1. mehaničko suzbijanje korova između redova kukuruza motokultivatorom, a unutar redova ručno okopavanje motikom, 2. mehaničko suzbijanje korova samo između redova kukuruza motokultivatorom bez suzbijanja unutar redova, 3. bez ikakvog suzbijanja korova. Na pokusnom polju je pronađeno 14 različitih vrsta korova od kojih su prevladavali Amaranthus retroflexus (običan štir), Ambrosia artemisiifolia (ambrozija), Chenopodium album (bijela loboda) i Sorghum halepense (divlji sirak). Najmanja zakorovljenost pokusnih parcela očekivano je bila na parcelama gdje je primijenjena varijanta 1 suzbijanja korova, kod varijante 2 je prosječna masa korova po 1 m2 bila 223%, a kod varijante 3 čak 334% veća u odnosu na varijantu 1. Prinosi kukuruza su bili obrnuto proporcionalni sa zakorovljenosti pokusnih parcela, najviši prinosi su ostvareni kod varijante 1 s prosjekom od 6015 kg ha-1, kod varijante 2 prosječni prinos je bio 2907 kg ha-1, a kod varijante 3 1242 kg ha-1. Kombinacija mehaničkog suzbijanja korova i ručnog okopavanja može biti alternativa korištenju herbicida na manjim obiteljskim gospodarstvima i u ekološkom uzgoju kukuruza.
An experiment with different variants of weed control in the maize crop was carried out in 2021 at a location next to the Markovo Polje settlement on silty loam soil. Three variants of weed control were applied: 1. mechanical weed control between the maize rows with a motocultivator and manual hoeing within the rows, 2. mechanical weed control only between the maize rows with a motocultivator without control within the rows, 3. without any control of weeds. In the experimental field, 14 different types of weeds were found, of which Amaranthus retroflexus, Ambrosia artemisiifolia, Chenopodium album and Sorghum halepense prevailed. As expected, the lowest weed infestation of the experimental plots was on the plots where variant 1 of weed control was applied, in variant 2 the average mass of weeds per 1 m2 was 223%, and in variant 3 it was even 334% higher compared to variant 1. Maize yields were inversely proportional to the weed infestation of the experimental plots, the highest yields were achieved in variant 1 with an average of 6015 kg ha-1, in variant 2 the average yield was 2907 kg ha-1, and in variant 3 1242 kg ha-1. The combination of mechanical weed control and manual hoeing can be an alternative to the use of herbicides on smaller family farms and in organic maize production.
Hazelnut fruit samples were collected over 2 years (2020 and 2021) and subjected to four different drying temperatures (100, 120, 140, and 160 °C) and four different drying times of 15, 30, 45, and ...60 min using conduction drying. The analyses performed showed that conduction drying at different temperatures and different drying times had a significant effect on the change in the composition of the hazelnut shell fuel and its mass properties. Comparing the untreated samples over two years and the samples after drying, it can be seen that in 2020, the drying treatment causes a decrease in the percentage of C and H, while in 2021, drying at 160 °C and 45 min causes an increase in C and H values. After treatment, the S content decreased on average, while the value of O increased or remained the same. The greatest increase in heating values (HHV and LHV) was observed at temperatures of 140 °C and 120 °C and the duration of 45 min. When drying was applied, a significant difference in mass change was observed at 120 °C, 100 °C, and 140 °C and 30 and 60 min process durations. The change in heating value is significantly affected by the parameters year of sampling, temperature, and time, while the change in mass of the hazelnut shell is most affected by drying time.
Agricultural biomass is one of the most important renewable energy sources. As a byproduct of corn, soybean and sunflower production, large amounts of biomass are produced that can be used as an ...energy source through conversion. In order to assess the quality and the possibility of the use of biomass, its composition and calorific value must be determined. The use of nonlinear models allows for an easier estimation of the energy properties of biomass concerning certain input and output parameters. In this paper, RFR (Random Forest Regression) and SVM (Support Vector Machine) models were developed to determine their capabilities in estimating the HHV (higher heating value) of biomass based on input parameters of ultimate analysis. The developed models showed good performance in terms of HHV estimation, confirmed by the coefficient of determination for the RFR (R2 = 0.79) and SVM (R2 = 0.93) models. The developed models have shown promising results in accurately predicting the HHV of biomass from various sources. The use of these algorithms for biomass energy prediction has the potential for further development.
Selecting cultivars with greater biomass results in higher yields and greater carbon sequestration. Storage of atmospheric carbon in the plant/soil pool contributes not only to food security but also ...to mitigating climate change and other agroecological benefits. The objective of this study was to determine: (1) grain, residue, and root biomass yields; (2) harvest indexes; (3) residue-to-product ratio; (4) root-to-shoot ratio; (5) biomass carbon and nitrogen contents; and (6) C:N ratios for two new and two old winter wheat cultivars. The greatest yield difference was found between old Srpanjka (the lowest) and new Kraljica (the highest) cultivar where grain, residue, root, and total biomass yield was higher by 38%, 91%, 71%, and 64%, respectively. Total biomass was composed of 40–47% grain, 10–11% roots, 32–36% stems + leaves, 9–11% chaff, and 1–2% spindle. The range of HI was 0.45–0.53, RPR 0.91–1.25, and R:S ratio 0.12–0.13. For all cultivars, positive carbon and negative nitrogen balance within the plant pool was determined. Still, root biomass and rhizodeposition carbon remain open questions for a better understanding of agroecosystems’ C dynamics.
Since the initial moisture content in sunflower seeds after the harvest is rather high, seeds must be processed by convection drying so that their quality can be maintained for as long as possible a ...period of time. Sunflower is an oilseed crop, which can be used both as food and as a feedstock for energy production. The aim of this paper is to determine the influence of the convection drying process (at 60 °C, 80 °C and 100 °C) on energy characteristics of seeds of four sunflower hybrids (Apolon, NK Brio, PR 63 A 90 and PR 63 D 82), which by their characteristics belong to early and medium-early hybrids. It will also be determined if the energy used in the drying process can be recovered through utilisation of energy from husk. On the basis of the obtained results, the changes in energy characteristics were identified, namely, the content of non-combustible matters (water, ash, coke, fixed carbon and nitrogen) and of combustible matters (carbon, sulphur, hydrogen, oxygen, volatile matter), as well as higher and lower heating values of sunflower seeds. The resulting data prove that convection drying of sunflower husk has a positive influence on its energy characteristics.
A significant problem in the use of pumpkin is the fact that its total mass is not used completely, but is thrown away and becomes waste. The meat is used for the production of flour, but after its ...production there are leftovers. The work includes two varieties of pumpkin (seed with shell and seed without shell). The aim of this study is to determine the impact of drying and variety on the quality of meat flour and the possibility of using residues after the production of peel and seed shells with the goal of producing energy. Drying will be carried out by convection at 50, 60, and 70 °C. The obtained results showed that Variety 1 (with shell) is better for flour production and energy efficiency. LHV of peel was 14.70 MJ/kg and shell 17.80 MJ/kg and classifies pumpkin residues as a very desirable raw material for green energy production.
Unazad dvadesetak godina na području Pitomače i Virovitice se intenzivirao uzgoj ljekovitog bilja, a posebno kamilice. Tako da je Republika Hrvatska jedna od najvećih proizvođača ljekovitog bilja u ...Europi. Najviše se izvozi u Italiju, Njemačku i skandinavske zemlje. Potvrđeno je da je ljekovito bilje (a tako i kamilica) najkvalitetnija u ovom dijelu Europe. U radu je prikazana suvremena linija strojeva i opreme za berbu i doradu kamilice.
In the last twenty years, the cultivation of medicinal herbs, especially chamomile, has intensified in the area of Pitomača and Virovitica. Thus, the Republic of Croatia is one of the largest producers of medicinal plants in Europe. It is mostly exported to Italy, Germany and Scandinavian countries. It has been confirmed that medicinal herbs (and so chamomile) are the highest quality in this part of Europe. The paper presents a modern line of machines and equipment for harvesting and dorado chamomile.
The most important process in immortelle is the extraction of the essential oil by distillation. The chemical properties of the plant depend largely on the cultivation type, climatic conditions and ...agrotechnical measures. In this work, studies were carried out on organically grown and wild immortelle harvested during the summer (July) and autumn (October) seasons of 2020. Immortelle samples were prepared by drying naturally in two ways: in direct sunlight and in shade. To extract the essential oil, immortelle was distilled in two ways: on an industrial and a laboratory scale. The essential oil was analyzed by gas chromatography to determine the composition and quality of the essential oil. The results of this work showed that the qualitative properties of the essential oil were influenced by the cultivation type, harvesting time, preparation method and distillation method. A higher yield (0.21% ± 0.03) of essential oil was obtained from wild immortelle whereas a better utilization rate (0.38% ± 0.09) of essential oil was obtained from the organically grown immortelle. It was also found that a higher yield of essential oil was obtained from the summer harvest (0.19% ± 0.01) and a higher utilization rate from the autumn harvest (0.33% ± 0.13) with the industrial scale distillation and shade drying. In general, better qualitative properties of immortelle essential oil were obtained from wild immortelle, which was confirmed by a chromatographic analysis and better content of γ-curcumene (16.64% ± 0.30) and neryl acetate (8.15% ± 0.19) and other constituents except α-pinene where organically grown had a higher share (24.27% ± 0.97).
Biomass as a renewable energy source includes energy crops that are not used for food but solely for biomass production with the goal of conversion to various forms of biofuel. Switchgrass, a ...perennial grass native to North America, has been explored as an energy crop for many years. It is suitable because it does not require much agrotechnical input, is highly resistant to pest infestation and disease development, and can provide very high biomass yields. The aim of this work was to determine the biomass quality of the mentioned plant in relation to the autumn and spring harvest, considering its use in direct combustion processes. Significant differences were found in the percentages of ash, carbon, nitrogen, sulfur, oxygen, and water, as well as in the percentages of micro and macro elements, in the harvest dates studied. Compared to the autumn, the moisture content decreased from 33.88% to 10.95% and ash content from 4.59% to 3.1% in the spring harvest, while the carbon content increased from 47.02% to 47.49%, dry matter from 38.91% to 89.22%, and heating value from 18.60 MJ kg−1 to 18.73 MJ kg−1. Shifting the harvest date from autumn to spring resulted in the production of higher quality biomass for use in combustion processes.
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