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Preharvest treatments with low-risk plant protection products can help apple growers fulfill the demands of supermarket chains regarding pesticide residues and marketing apples under 0-residue brands
Andrej Paušič, Mihaela Roškarič, Mario Lešnik, 2023, original scientific article

Abstract: As a result of worried consumer pressure, European supermarket chains (ESC) have developed very strict rules about the number and concentration of pesticide active substance residues (AS) accepted in fruits. So-called fruit quality toxicological burden indicators were developed. If fruit suppliers do not comply with ESC requirements, their fruit is often rejected. It is becoming increasingly difficult for apple producers to meet all the requirements of the ESC, so they need new residue reduction tools. One of the options to lower the concentrations of residue on apples is a preharvest application of low-risk preparations (LRP) based on potassium bicarbonate (KHCO3) = PBC, coconut di-ethanol amide ((CH3(CH2)nC(=O)N(CH2CH2OH)2) = DEA, hydrogen peroxide (H2O2) = HP, and a mixture of microbes (EM) that have the ability to dissolve or disintegrate the AS residue. Trials were carried out to test the concept mentioned above. The application of LRP during the last four weeks of preharvest significantly reduced the residue concentration of pesticide AS in apples. Reduction rates among 25 active substances ranged from 0 to 100%, depending on the combination of LRP and AS. HP had the highest capacity to accelerate AS degradation, PB was the second most efficient, and DEA and EM displayed a low residue disintegration ability. The application of the tested LRP can enable apple growers to produce fruits with significantly lower residue concentrations and allows them to comply more successfully with strict ESC rules based on the calculations of toxicological burden indicators.
Keywords: hydrogen peroxide, potassium bicarbonate, effective microbes, detergent, pesticide residues, fruit marketing rules
Published in DKUM: 19.04.2024; Views: 92; Downloads: 1
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Converting waste into products and energy using complete circular economy and the hydrogen effect technique to reduce dependence on natural gas
Anita Kovač Kralj, 2023, original scientific article

Abstract: Conversion of waste into products and energy has the potential to reduce CO2 emis-sion through implementation of a complete circular economy and utilisation of the hy-drogen effect technique. This study considers the novelties of the hydrogen effect tech-nique, which incorporates an upgraded input unit mathematical model. It includes real-simulated results obtained using an Aspen Plus & REG; simulator, and enlarged production. This technique is developed for optimal municipal solid waste (MSW) combustion, gas-ification, and reforming, presented as an upgraded input unit for syngas production, which can reduce CO2 emissions by 3 & BULL;106 kmol a-1. This approach is exemplified by utilizing existing methanol and dimethyl ether production processes from natural gas, as they can be achieved and exceeded using MSW with varying hydrogen amounts. The optimal upgraded methanol and dimethyl ether production processes can increase pro-duction by 47 % and 16 %, including only the upgraded input unit, as well as decrease the temperature in the product reactors by 30 & DEG;C.
Keywords: waste gasification, flue gas, syngas, hydrogen, circular economy, combustion
Published in DKUM: 13.02.2024; Views: 188; Downloads: 15
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A review of the use of Rankine cycle systems for hydrogen production
Urška Novosel, Jurij Avsec, 2020, original scientific article

Abstract: The vast majority of steam power plants in the world are based on the Rankine cycle. It is a wellknown, trustworthy process that uses water or water vapour as a working medium, which supplies heat from various primary energy sources: fossil fuels, renewable energy sources (solar energy, energy from wood biomass, etc.) or a combination of both. With the Rankine cycle, energy sources other than electricity can be produced, which can be used as the primary energy source for various applications. The present article focuses on the production of hydrogen in addition to electricity; therefore, two energy sources are obtained from the same system with a few modifications of the existing power plant for further exploitation. There are several processes for hydrogen production using the Rankine cycle; in the present article, two processes are focused on: using part of the electricity produced and obtaining hydrogen by electrolysis of water or using part of high quality steam (basically heat energy) in combination with electricity and obtaining hydrogen by a thermochemical copper-chlorine process. Each of these processes has its advantages and disadvantages, which are presented in the present article with an example model of a power plant.
Keywords: Rankine cycle, hydrogen production, electrolysis, thermochemical process
Published in DKUM: 01.12.2023; Views: 331; Downloads: 3
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Impacts of zero-emission powertrains based on hydrogen technologies in public transport
Niko Natek, Boštjan Krajnc, 2020, original scientific article

Abstract: This article reviews the development potentials and environmental impact of introducing category M3 vehicles (for passenger transport/buses) with fuel cell electric powertrains to an urban and inter-urban public transport service (PTS) to be operated in the Savinjsko-Šaleška region. The main focus is the demonstration of the PTS modelling and preliminary environmental impact assessment of the operation compared to conventional (modern) diesel-powered internal combustion engines.
Keywords: Hydrogen, Fuel Cell, Transport, Energy efficiency, Green-house gas emissions, Energy transition, Environment, Public transport service, Internal combustion Engine, CO2
Published in DKUM: 15.11.2023; Views: 315; Downloads: 5
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Energy analysis of hydrogen use in road transport of the Republic of Croatia
Franco Krog, Jurij Avsec, 2022, professional article

Abstract: In this paper, we will calculate the needs for hydrogen if all traffic in Croatia was driven by hydrogen. In the article, we will determine the required amount in several ways. First, we will briefly describe fuel cell cars and the extent to which the amount of exhaust gases would be reduced. We will then explain the ways of obtaining hydrogen, its transport and what the purchase costs would be. Finally, we will compare the results and draw some conclusions.
Keywords: hydrogen, hydrogen technologies, hydrogen acquisition, transport
Published in DKUM: 30.10.2023; Views: 343; Downloads: 7
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Hydrogen production using a thermochemical cycle
Jurij Avsec, Urška Novosel, Dušan Strušnik, 2022, original scientific article

Abstract: Sustainable methods of clean fuel production are needed throughout the world due to depleting oil reserves and the need to reduce carbon dioxide emissions. The technology based on fuel cells for electricity production or the transport sector has already been developed. However, a key missing element is a large-scale method of hydrogen production. The copper-chlorine (CuCI) combined thermochemical cycle is a promising thermochemical cycle that can produce large amounts of cheap hydrogen. A particularly promising part of this process is its use in combination with nuclear or thermal power plants. This paper focuses on a CuCl cycle and describes the models used to calculate thermodynamic and transport properties. This paper discusses the mathematical model for computing the thermodynamic properties for pure HCl and CuCl2. The mathematical model developed for the solid phase takes into account vibrations of atoms in molecules and intermolecular forces. This mathematical model can be used for the calculation of the thermodynamic properties of polyatomic crystals on the basis of the Einstein and Debye equations. The authors of this paper developed the model in the low temperature and high temperature region. All the analytical data have been compared with some experimental results and show a relatively good match. For the solid phase, the authors developed a model to calculate thermal conductivity based on electron and phonon contributions.
Keywords: thermodynamics, energy, hydrogen production, solid phase, fluid phase
Published in DKUM: 30.10.2023; Views: 262; Downloads: 5
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