1. Environmental priorities in the circular economy : examples from iron-based technologiesAndreea Oarga-Mulec, Uroš Luin, Keith R. Skene, Matjaž Valant, 2024, objavljeni znanstveni prispevek na konferenci Opis: The circular economy (CE) framework is crucial for promoting resource efficiency and minimizing waste, but it cannot achieve its sustainability goals alone. To achieve a truly sustainable future, broader social, environmental and economic aspects need to be taken into account. Rather than separating biological and technological cycles, as the CE principles are depicted in the Ellen MacArthur Foundation’s butterfly diagram (EMF, 2017), we propose an integrated approach that prioritises environmental aspects and includes a conceptual framework, socio-economic changes and implementation processes. It is crucial to re-evaluate the environmental aspects and strengthen their importance within the CE framework. Within this concept we present the case of iron, the most widely used metal, widely available compared to others and has been an essential part of societal development for more than 5,000 years. With its abundance, safety and electrochemical properties, iron is an ideal material for low-carbon energy technologies. We discuss how advanced iron-based technologies have a high potential to be successfully integrated into the CE, we evaluate different electrochemical energy storage systems and present advances in thermochemical Fe-Cl cycles for hydrogen production. An innovative thermal system for hydrogen production based on the thermochemical Fe-Cl cycle was evaluated in a life cycle assessment (LCA) study and shows the importance of choosing sustainable energy sources to minimise environmental impact. Sustainable production methods for iron are also analysed to demonstrate their potential to reduce the carbon footprint of the iron and steel industry. Finally, efforts should focus on minimising environmental impact and optimising resource recovery.
Ključne besede: circular economy, resource efficiency, sustainability, iron, hydrogen
Objavljeno v RUNG: 25.11.2024; Ogledov: 1020; Prenosov: 0
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4. Defining worst-performing buildings in Slovenia based on EPCsMarjana Šijanec-Zavrl, Henrik Gjerkeš, 2023, objavljeni znanstveni prispevek na konferenci Opis: The 2021 EC proposal for EPBD recast planned inter alia the harmonization of energy performance certificates (EPCs) across EU and definition of minimum energy performance (MEP) standards to support the renovation of worst-performing buildings. Rescaling of EPCs to a common EU ranking and consequently setting MEP standards is a task for the near future, but current planning of building renovation to meet decarbonization by 2050 may only relay on data in Slovenian EPCs from 2013-2022 data base. The paper presents the analysis of energy related indicators in existing Slovenian EPCs in order to demonstrate that existing EPCs issued in last decade can be used to define 15% of worst-performing buildings prioritized for deep and NZEB renovation, if combined with other indicators, like heat demand.
Ključne besede: energy performance indicators, decarbonization, energy efficiency, building renovation
Objavljeno v RUNG: 27.11.2023; Ogledov: 2038; Prenosov: 12
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5. Implementation of the EPBD in Slovenia – Status in 2020Marjana Šijanec Zavrl, Miha Tomšič, Henrik Gjerkeš, Erik Potočar, 2021, končno poročilo o rezultatih raziskav Opis: The Concerted Action EPBD (CA EPBD) addresses the Energy Performance of Buildings Directive (EPBD). It aims to contribute to the reduction of energy use in European buildings, through the exchange of knowledge and best practices in the field of energy efficiency and energy savings between all 28 EU Member States plus Norway.
The CA EPBD is a joint initiative between the EU Member States and the European Commission. It involves representatives of national ministries or their affiliated institutions who are in charge of preparing the technical, legal and administrative framework for the Energy Performance of Buildings Directive in each EU Member State, plus Norway. The objective is to enhance the sharing of information and experiences from national adoption and implementation of this important European legislation.
The transposition of the EPBD in Slovenia is the overall responsibility of the Ministry of Infrastructure and was primarily transposed by the Energy Act (EZ-1), covering the topics of NZEB, energy performance certification, inspection of heating and AC systems and energy efficiency information programmes. The Act on Energy Efficiency (ZURE) integrates the EZ-1 articles related to the EPBD.
The revision of the building codes (PURES) is still in progress and planned for publication in late 2021. It will contain detailed technical requirements for NZEB based on the technical definition given in the national NZEB action plan, and the revision of the calculation methodology according to a new set of CEN EPBD standards.
Important recent steps in EPBD implementation are the application of the central national electronic register of EPCs and associated software, the independent control system for EPCs, first steps in the cross-linking of e-registries for EPCs, inspections and public buildings, as well as wide information activities implemented by the Eco Fund concerning financial instruments available for the energy renovation of buildings.
Ključne besede: Concerted Action, Energy Performance of Buildings Directive, Act on Energy Efficiency, Slovenia
Objavljeno v RUNG: 02.11.2023; Ogledov: 2188; Prenosov: 18
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6. Current status and prospects of surface detector of the TAx4 experimentE. Kido, Jon Paul Lundquist, 2022, objavljeni znanstveni prispevek na konferenci Opis: Telescope Array (TA) is the largest ultrahigh energy cosmic-ray (UHECR) observatory in the Northern Hemisphere. A surface detector (SD) array covers approximately 700 km^2, and the SD array is surrounded by three fluorescence detector (FD) stations. TA has found evidence for a cluster of cosmic rays with energies greater than 57 EeV from the TA SD data. In order to confirm this evidence with more data, we started the TAx4 experiment which expands the detection area using new SDs and FDs. We started construction of new SDs which are arranged in a square grid with 2.08 km spacing at the north east and south east of the TA SD array. More than half of the new SDs are already deployed and running. We present the current status of the TAx4 SD, trigger efficiency and exposure prospects for the highest energy part of the cosmic ray spectrum.
Ključne besede: Telescope Array, TAx4, indirect detection, surface detection, ground array, ultra-high energy, cosmic rays, trigger efficiency
Objavljeno v RUNG: 04.10.2023; Ogledov: 2497; Prenosov: 12
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7. The challenge with high permittivity acceptors in organic solar cells : a case study with Y-series derivativesPeter Fürk, Suman Mallick, Thomas Rath, Matiss Reinfelds, Mingjian Wu, Erdmann Spiecker, Nikola Simic, Georg Haberfehlner, Gerald Kothleitner, Barbara Ressel, 2023, izvirni znanstveni članek Opis: Y-series acceptors have brought a paradigm shift in terms of power conversion efficiencies of organic solar cells in the last few years. Despite their high performance, these acceptors still exhibit substantial energy loss, stemming from their low-permittivity nature. To tackle the energy loss situation, we prepared modified Y-series acceptors with improved permittivities via an alternative synthetic route.
Ključne besede: solar cells, Y-series acceptors, morphology, efficiency measurements
Objavljeno v RUNG: 29.06.2023; Ogledov: 2826; Prenosov: 14
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8. Efficiency of the grid energy storage technology based on iron-chloride material cycleUroš Luin, doktorska disertacija Opis: Future high-capacity energy storage technologies are crucial for a highly renewable energy mix, and their mass deployment must rely on cheap and abundant materials, such as iron chloride. The iron chloride electrochemical cycle (ICEC), suitable for long-term grid energy storage using a redox potential change of Fe2+/Fe, involves the electrolysis of a highly concentrated aqueous FeCl2 solution yielding solid iron deposits. For the high overall energy efficiency of the cycle, it is crucial maximizing the energy efficiency of the electrolysis process. The thesis presents a study of the influence of electrolysis parameters on energy efficiency, performed in an industrial-type electrolyzer system. We studied the conductivity of the FeCl2 solution as a function of concentration and temperature and correlated it with the electrolysis energy efficiency as a function of current density. The contribution of the resistance polarization increases with the current density, causing a decrease in overall energy efficiency. The highest energy efficiency of 89 ±3 % was achieved using
2.5 mol dm-3 FeCl2 solution at 70 °C and a current density of 0.1 kA m-2.
In terms of the energy input per Fe mass, this means 1.88 Wh g-1. The limiting energy input per mass of the Fe-deposit, calculated by extrapolating experimental results toward Eocell potential, was found to be 1.76 Wh g-1. For optimal long-duration electrolysis efficiency and performance, the optimal catholyte concentration range is
1-2 mol dm-3 FeCl2. We performed in situ X-ray absorption spectroscopy experimental studies to validate theoretical conclusions from literature related to the population and structure of Fe-species in the FeCl2 (aq) solution at different concentrations (1 - 4 mol dm-3) and temperatures (25 - 80 °C). This revealed that at low temperature and low FeCl2 concentration, the octahedral first coordination sphere around Fe is occupied by one Cl ion at a distance of 2.33 (±0.02) Å and five H2O at a distance of 2.095 (±0.005) Å. The structure of the ionic complex gradually changes with an increase in temperature and/or concentration. The apical H2O is substituted by a Cl ion to yield a neutral Fe[Cl2(H2O)4]0. The transition from the charged Fe[Cl(H2O)5]+ to the neutral Fe[Cl2(H2O)4]0 causes a significant drop in the solution conductivity, which well correlates with the existing state-of-the-art conductivity models. An additional steric impediment of the electrolytic cell is caused by the predominant neutral species present in the catholyte solution at high concentration. This correlates with poor electrolysis performance at a very high catholyte concentration (4 mol dm-3 FeCl2), especially at high current densities (> 1 kA m-2). The neutral Fe[Cl2(H2O)4]0 complex negatively affects the anion exchange membrane ion (Cl-) transfer and lowers the concentration of electroactive species (Fe[Cl(H2O)5]+) at the cathode surface. The kinetics of hydrogen evolution from the reaction between Fe powder and HCl acid was studied under the first-order reaction condition. The activation energy was determined to be 55.3 kJ mol-1.
Ključne besede: ICEC, Power-to-Solid, energy storage, hydrogen, ferrous chloride, electrolysis, Fe deposition, efficiency, XAS, structure and population, ionic species, ion association, conductivity
Objavljeno v RUNG: 18.04.2023; Ogledov: 3283; Prenosov: 50 (1 glas)
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9. Development of Zinc Oxide-Multi-Walled Carbon Nanotube hybrid nanofluid for energy-efficient heat transfer application: A thermal lens studyMohanachandran Nair Sindhu Swapna, 2021, izvirni znanstveni članek Opis: This paper addresses the need for developing an energy-efficient hybrid nanofluid with zinc oxide–multi-walled carbon nanotube (ZnO-MWCNT) for overcoming the bottleneck of efficient heat transfer in thermal systems. The concentration-dependent thermal diffusivity modifications are analyzed using the highly sensitive mode mismatched thermal lens technique. The hybrid composite is prepared by the solid-state mixing and annealing of a pure multi-walled carbon nanotube (MWCNT) and zinc oxide (ZnO), synthesized by the solution combustion method. The composite formation is studied by structural, morphological, and optical characterization techniques. Among the three nanofluids ZnO, MWCNT, and ZnO-MWCNT, the composite exhibits a drastic enhancement in thermal diffusivity at a lower solid volume fraction of 0.047 mg/ml containing 0.009 mg/ml of MWCNT. All the nanofluids show an optimum concentration beyond which the thermal diffusivity decreases with the nanoparticle concentration. Thus, this study suggests the potential application of ZnO-MWCNT hybrid nanofluids in thermal system design to enhance internal combustion engines' efficiency during cold-start.
Ključne besede: Zinc Oxide, MWCNT, hybrid nanofluid, thermal lens, diffusivity, engine efficiency
Objavljeno v RUNG: 30.06.2022; Ogledov: 3031; Prenosov: 0
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10. Fractal and spectroscopic analysis of soot from internal combustion enginesMohanachandran Nair Sindhu Swapna, SARITHA DEVI H V, RAJ VIMAL, Sankararaman S, 2018, izvirni znanstveni članek Opis: Today diesel engines are used worldwide for various applications and very importantly in transportation. Hydrocarbons are the most widespread precursors among carbon sources employed in the production of carbon nanotubes (CNTs). The aging of internal combustion engine is an important parameter in deciding the carbon emission and particulate matter due to incomplete combustion of fuel. In the present work, an attempt has been made for the effective utilization of the aged engines for potential applicationapplications in fuel cells and nanoelectronics. To analyze the impact of aging, the particulate matter rich in carbon content areis collected from diesel engines of different ages. The soot with CNTs is purified by the liquid phase oxidation method and analyzed by Field Emission Scanning Electron Microscopy, High-Resolution Transmission Electron Microscopy, Energy Dispersive Spectroscopy, UV-Visible spectroscopy, Raman spectroscopy and Thermogravimetric analysis. The SEM image contains self-similar patterns probing fractal analysis. The fractal dimensions of the samples are determined by the box counting method. We could find a greater amount of single-walled carbon nanotubes (SWCNTs) in the particulate matter emitted by aged diesel engines and thereby giving information about the combustion efficiency of the engine. The SWCNT rich sample finds a wide range of applications in nanoelectronics and thereby pointing a potential use of these aged engines.
Ključne besede: Fractals, internal combustion engine, efficiency, soot, carbon nanoparticle
Objavljeno v RUNG: 30.06.2022; Ogledov: 2680; Prenosov: 0
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