1. Life cycle assessment of black and greywater treatment solutions for remote and sensitive areasAndreea Oarga-Mulec, Janez Turk, Petra Gerbec, Petter D. Jenssen, Katja Malovrh Rebec, Matjaž Valant, 2023, original scientific article Keywords: life cycle assessment, sanitation systems, sustainability, remote areas, circular economy
Published in RUNG: 20.02.2023; Views: 1397; Downloads: 3
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2. Correlation between FeCl2 electrolyte conductivity and electrolysis efficiencyUroš Luin, Matjaž Valant, Iztok Arčon, 2022, published scientific conference contribution abstract Abstract: The electrolysis efficiency is an important aspect of the Power-to-Solid energy storage technology (EST) based
on the iron chloride electrochemical cycle [1]. This cycle employs an aqueous FeCl2 catholyte solution for the
electro-reduction of iron. The metal iron deposits on the cathode. The energy is stored as a difference in the
redox potential of iron species. Hydrogen, as an energy carrier, is released on demand over a fully controlled
hydrogen evolution reaction between metallic Fe0 and HCl (aq) [1]. Due to these characteristics, the cycle is
suitable for long-term high-capacity and high-power energy storage. In a previous work [2] we revealed that
the electrolyte conductivity linearly increases with temperature. Contrary, the correlation between the
electrolyte concentration and efficiency is not so straightforward. Unexpectedly small efficiency variations were
found between 1 and 2.5 mol dm-3 FeCl2 (aq) followed by an abrupt efficiency drop at higher concentrations.
To explain the behavior of the observed trends and elucidate the role of FeCl2 (aq) complex ionic species we
performed in situ X-ray absorption studies. We made a dedicated experimental setup, consisting of a tubular
oven and PMMA liquid absorption cell, and performed the measurements at the DESY synchrotron P65
beamline. The XAS investigation covered XANES and EXAFS analyses of FeCl2 (aq) at different
concentrations (1 - 4 molL-1) and temperatures (25 - 80 °C). We found 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 water molecules at a distance of 2.095 (±0.005) Å [3]. The structure of the ionic complex
gradually changes with an increase in temperature and/or concentration. The apical water molecule is
substituted by a chlorine ion to yield a neutral Fe[Cl2(H2O)4]0. The transition from the single 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 conductivity models [3].
[1] M. Valant, “Procedure for electric energy storage in solid matter. United States Patent and
Trademark Office. Patent No. US20200308715,” Patent No. US20200308715, 2021.
[2] U. Luin and M. Valant, “Electrolysis energy efficiency of highly concentrated FeCl2 solutions
for power-to-solid energy storage technology,” J. Solid State Electrochem., vol. 26, no. 4, pp.
929–938, Apr. 2022, doi: 10.1007/S10008-022-05132-Y.
[3] U. Luin, I. Arčon, and M. Valant, “Structure and Population of Complex Ionic Species in
FeCl2 Aqueous Solution by X-ray Absorption Spectroscopy,” Molecules, vol. 27, no. 3, 2022,
doi: 10.3390/molecules27030642.
Keywords: Iron chloride electrochemical cycle, Power-to-Solid energy storage, XANES, EXAFS, electrical
conductivity, electrolyte complex ionic species structure and population
Published in RUNG: 26.09.2022; Views: 1491; Downloads: 0 (1 vote)
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6. Whole-life carbon emissions benchmarks for buildings in SloveniaMarjana Šijanec-Zavrl, Henrik Gjerkeš, 2021, short scientific article Abstract: According to the European Green Deal decarbonisation of EU building stock is needed on the way to turning EU into the first climate neutral continent by 2050. Directive (2010/31/EU) EPBD led to significant reduction of operational energy in new buildings and renovation. By energy efficiency first principle and by increasing renewable energy sources it contributed to reduction of primary energy and operational CO2 emissions. But the orientation towards lifecycle thinking and circularity in the building sector revealed the need to tackle the whole-life carbon emissions, where the operational and embodied carbon contribute significantly. In the absence of benchmarks for embodied carbon emissions in this contribution the operational and embodied carbon indicators from recent studies are compared with the available corresponding data in Slovenian energy performance certificates.
Keywords: carbon emissions, life cycle assessment, buildings
Published in RUNG: 29.10.2021; Views: 1744; Downloads: 0
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9. Two regimes in the regularity of sunspot numberAlexander Shapoval, Jean-Louis Le Mouël, Vincent Courtillot, M. Shnirman, 2013, original scientific article Abstract: Sunspot numbers WN display quasi-periodical variations that undergo regime changes. These irregularities could indicate a chaotic system and be measured by Lyapunov exponents. We define a functional λ (an "irregularity index") that is close to the (maximal) Lyapunov exponent for dynamical systems and well defined for series with a random component: this allows one to work with sunspot numbers. We compute λ for the daily WN from 1850 to 2012 within 4 yr sliding windows: λ exhibit sharp maxima at solar minima and secondary maxima at solar maxima. This pattern is reflected in the ratio R of the amplitudes of the main versus secondary peaks. Two regimes have alternated in the past 150 yr, R1 from 1850 to 1915 (large λ and R values) and R2 from 1935 to 2005 (shrinking difference between main and secondary maxima, R values between 1 and 2). We build an autoregressive model consisting of Poisson noise plus an 11 yr cycle and compute its irregularity index. The transition from R1 to R2 can be reproduced by strengthening the autocorrelation a of the model series. The features of the two regimes are stable for model and WN with respect to embedding dimension and delay. Near the time of the last solar minimum (~2008), the irregularity index exhibits a peak similar to the peaks observed before 1915. This might signal a regime change back from R2 to R1 and the onset of a significant decrease of solar activity.
Keywords: Lyapunov exponent, solar activity, solar cycle
Published in RUNG: 19.04.2021; Views: 1798; Downloads: 57
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10. The Modal Cycle vs. Negation in SlovenianFranc Marušič, Rok Žaucer, 2016, independent scientific component part or a chapter in a monograph Abstract: One of the possible ways of expressing possibility in affirmative
sentences in Slovenian is with a modal adverb that combines with a finite verb. Under negation, a modal auxiliary must be used instead of the modal adverb. The pattern with a modal adverb that combines with a finite verb is a peculiarity among other Slavic languages as well as European languages more generally (Hansen 2005, Olmen & Auwera, in press). Looking at diachronic data, which reveal an earlier stage without the modal adverb as well as a subsequent stage with cooccurrence of the modal adverb and the modal auxiliary, we propose that the change be analyzed in terms of the linguistic cycle (van Gelderen 2011), with the modal adverb originating as a reinforcer of the modal auxiliary and then grammaticalizing into a modal. The modal-adverb strategy could not generalize to contexts with sentential negation because of the hierarchical order of the relevant functional projections and the characteristics of the negative particle.
Keywords: Modal adverb, modal cycle, linguistic cycle, Slovenian
Published in RUNG: 12.12.2016; Views: 4434; Downloads: 0
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