Evaluation of the economic and environmental performance of low-temperature heat to power conversion using a reverse electrodialysis - Multi-effect distillation system

In the examined heat engine, reverse electrodialysis (RED) is used to generate electricity from the salinity difference between two artificial solutions. The salinity gradient is restored through a multi-effect distillation system (MED) powered by low-temperature waste heat at 100 ◦C. The current work presents the first comprehensive economic and environmental analysis of this advanced concept, when varying the number of MED effects, the system sizing, the salt of the solutions, and other key parameters. The levelized cost of electricity (LCOE) has been calculated, showing that competitive solutions can be reached only when the system is at least medium to large scale. The lowest LCOE, at about 0.03 €/kWh, is achieved using potassium acetate salt and six MED effects while reheating the solutions. A similar analysis has been conducted when using the system in energy storage mode, where the two regenerated solutions are stored in reservoir tanks and the RED is operating for a few hours per day, supplying valuable peak power, resulting in a LCOE just below 0.10 €/kWh. A life-cycle assessment has been also carried out, showing that the case with the lowest environmental impact is the same as the one with the most attractive economic performance. Results indicate that the material manufacturing has the main impact; primarily the metallic parts of the MED. Overall, this study highlights the development efforts required in terms of both membrane performance and cost reduction, in order to make this technology cost effective in the future

Reverse electrodialysis heat engine with multi-effect distillation: Exergy analysis and perspectives

The increasing worldwide energy demand is rising the interest on alternative power production technologies based on renewable and emission-free energy sources. In this regard, the closed-loop reverse electrodialysis heat engine is a promising technology with the potential to convert low-grade heat into electric power. The reverse electrodialysis technology has been under investigation in the last years to explore the real potentials for energy generation from natural and artificial solutions, and recent works have been addressing also the potential of its coupling with regeneration strategies, looking at medium and large energy supply purposes. In this work, for the first time, a comprehensive exergy analysis at component level is applied to a reverse electrodialysis heat engine with multi-effect distillation in order to determine the real capability of the waste heat to power conversion, identifying and quantifying the sources of exergy destruction. In particular, sensitivity analyses have been performed to assess the influence of the main operating conditions (i.e. solutions concentration and velocity) and design features (aspect ratio of the pile), characterizing the most advantageous scenarios and including the effect of new generations of membranes. Results show that the multi-effect distillation unit is the main source of exergy destruction. Also, using high-performing membranes, inlet solutions concentration and velocity of 4.5\u20130.01 mol/L and 0.2\u20130.36 cm/s, respectively, a global exergy efficiency of 24% is reached for the system, proving the high potential of this technology to sustainably convert waste heat into power

Wave farm effects on the coast: The alongshore position

publisher: Elsevier articletitle: Wave farm effects on the coast: The alongshore position journaltitle: Science of The Total Environment articlelink: https://doi.org/10.1016/j.scitotenv.2018.05.281 content_type: article copyright: © 2018 Elsevier B.V. All rights reserved

Synthesis of Gold Nanoparticles and Incorporation to a Porous Nickel Electrode to Improve its Catalytic Performance Towards the Hydrogen Evolution Reaction

[EN] Gold nanoparticles (AuNPs) were successfully synthesized by a facile chemical reduction method in the presence of the stabilizer polyvinylpyrrolidone and characterized by UV-vis spectroscopy and transmission electron microscopy. The gold nanoparticles were then incorporated onto the surface of a porous Ni electrode by simple addition of the nanoparticles suspension, followed by heat treatment at 350 degrees C for 1 h under nitrogen atmosphere. The modified electrode was morphologically characterized by field emission scanning electron microscopy. Then, the effect of the modification with Au nanoparticles was studied in the hydrogen evolution reaction (HER) by pseudo-steady-state polarization curves and electrochemical impedance spectroscopy (EIS), at different temperatures and compared with a pure porous Ni electrode. The modified electrode showed a clear improvement in its catalytic performance mainly due to the intrinsic catalytic activity of the Au nanoparticles. From the Tafel representations and the EIS, it was estimated that the HER on the electrode modified with AuNPs takes place by the Volmer-Heyrovsky mechanism.Ramiro Medina Orta is grateful to Consejo Nacional Ciencia y Tecnologia and Consejo Potosino de Ciencia y Tecnologia for the doctorate scholarship 472041. Also, he wishes to thank the Instituto de Metalurgia of Universidad Autonoma de San Luis Potosi for the opportunity of a research stay. We also thank Dr. Nubia Arteaga Larios and M.M.I.M. Martha Alejandra Lomeli Pacheco (Instituto de Metalurgia, Universidad Autonoma de San Luis Potosi) for their help with the UV-vis spectroscopy.Medina-Orta, R.; Labrada-Delgado, GJ.; Silva-Pereyra, HG.; Ortega Navarro, EM.; Pérez-Herranz, V.; Sánchez-Loredo, MG. (2022). Synthesis of Gold Nanoparticles and Incorporation to a Porous Nickel Electrode to Improve its Catalytic Performance Towards the Hydrogen Evolution Reaction. Electrocatalysis. 13(1):47-61. https://doi.org/10.1007/s12678-021-00690-7476113

First survey of Wolf-Rayet star populations over the full extension of nearby galaxies observed with CALIFA

The search of extragalactic regions with conspicuous presence of Wolf-Rayet (WR) stars outside the Local Group is challenging task due to the difficulties in detecting their faint spectral features. In this exploratory work, we develop a methodology to perform an automated search of WR signatures through a pixel-by-pixel analysis of integral field spectroscopy (IFS) data belonging to the Calar Alto Legacy Integral Field Area survey, CALIFA. This technique allowed us to build the first catalogue of Wolf-Rayet rich regions with spatially-resolved information, allowing to study the properties of these complexes in a 2D context. The detection technique is based on the identification of the blue WR bump (around He II 4686 {\AA}, mainly associated to nitrogen-rich WR stars, WN) and the red WR bump (around C IV 5808 {\AA} and associated to carbon-rich WR stars, WC) using a pixel-by-pixel analysis. We identified 44 WR-rich regions with blue bumps distributed in 25 galaxies of a total of 558. The red WR bump was identified only in 5 of those regions. We found that the majority of the galaxies hosting WR populations in our sample are involved in some kind of interaction process. Half of the host galaxies share some properties with gamma-ray burst (GRB) hosts where WR stars, as potential candidates to being the progenitors of GRBs, are found. We also compared the WR properties derived from the CALIFA data with stellar population synthesis models, and confirm that simple star models are generally not able to reproduce the observations. We conclude that other effects, such as the binary star channel (which could extend the WR phase up to 10 Myr), fast rotation or other physical processes that causes the loss of observed Lyman continuum photons, are very likely affecting the derived WR properties, and hence should be considered when modelling the evolution of massive stars.Comment: 33 pages, accepted for publication in A&

Nudging Cooperation in a Crowd Experiment

We examine the hypothesis that driven by a competition heuristic, people don't even reflect or consider whether a cooperation strategy may be better. As a paradigmatic example of this behavior we propose the zero-sum game fallacy, according to which people believe that resources are fixed even when they are not. We demonstrate that people only cooperate if the competitive heuristic is explicitly overridden in an experiment in which participants play two rounds of a game in which competition is suboptimal. The observed spontaneous behavior for most players was to compete. Then participants were explicitly reminded that the competing strategy may not be optimal. This minor intervention boosted cooperation, implying that competition does not result from lack of trust or willingness to cooperate but instead from the inability to inhibit the competition bias. This activity was performed in a controlled laboratory setting and also as a crowd experiment. Understanding the psychological underpinnings of these behaviors may help us improve cooperation and thus may have vast practical consequences to our society.Fil: Niella, Tamara. Universidad Torcuato di Tella; ArgentinaFil: Stier, Nicolas. Universidad Torcuato di Tella; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Sigman, Mariano. Universidad Torcuato di Tella; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Implementación de una normativa sanitaria adaptada a sistemas productivos de la Agricultura Familiar en caprinos y ovinos de Tucumán

Informe elaborado en el marco del Proyecto Minifundio “Fortalecimiento socio-productico de productores caprinos de Taco Ralo”; INTA-AUDEAS-CONADEV “Mejora del estado sanitario de enfermedades zoonóticas de rumiantes mayores y menores de Tucumán, Santiago del Estero y Catamarca”; Proyecto Regional Tucumán Sur; y Proyecto Nacional de Sanidad Animal “Epidemiología y desarrollo de estrategias para la prevención y control de enfermedades que afectan la salud pública, enfermedades exóticas y limitantes del comercio internacional”.EEA FamailláFil: Saldaño, Silvina Alejandra. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Famaillá. Agencia de Extensión Rural Simoca; ArgentinaFil: Garbaccio, Sergio Gabriel. Instituto Nacional de Tecnología Agropecuaria (INTA). Instituto de Patobiología; ArgentinaFil: Mendez, Ramiro Ezequiel. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Famaillá. Agencia de Extensión Rural Simoca; ArgentinaFil: Aznar, R. Universidad Nacional de Tucumán. Facultad de Agronomía y Zootecnia; ArgentinaFil: Delgado, Fernando Oscar. Instituto Nacional de Tecnología Agropecuaria (INTA). Instituto de Patobiología; ArgentinaFil: Cruz, L. Universidad Nacional de Tucumán. Facultad de Agronomía y Zootecnia; ArgentinaFil: Ortega, G. Tucumán (provincia). Dirección de Ganadería; Argentin

Stellar Population gradients in galaxy discs from the CALIFA survey

While studies of gas-phase metallicity gradients in disc galaxies are common, very little has been done in the acquisition of stellar abundance gradients in the same regions. We present here a comparative study of the stellar metallicity and age distributions in a sample of 62 nearly face-on, spiral galaxies with and without bars, using data from the CALIFA survey. We measure the slopes of the gradients and study their relation with other properties of the galaxies. We find that the mean stellar age and metallicity gradients in the disc are shallow and negative. Furthermore, when normalized to the effective radius of the disc, the slope of the stellar population gradients does not correlate with the mass or with the morphological type of the galaxies. Contrary to this, the values of both age and metallicity at $\sim$2.5 scale-lengths correlate with the central velocity dispersion in a similar manner to the central values of the bulges, although bulges show, on average, older ages and higher metallicities than the discs. One of the goals of the present paper is to test the theoretical prediction that non-linear coupling between the bar and the spiral arms is an efficient mechanism for producing radial migrations across significant distances within discs. The process of radial migration should flatten the stellar metallicity gradient with time and, therefore, we would expect flatter stellar metallicity gradients in barred galaxies. However, we do not find any difference in the metallicity or age gradients in galaxies with without bars. We discuss possible scenarios that can lead to this absence of difference.Comment: 24 pages, 17 figures, accepted for publication in A&

Imprints of galaxy evolution on H ii regions Memory of the past uncovered by the CALIFA survey

H ii regions in galaxies are the sites of star formation and thus particular places to understand the build-up of stellar mass in the universe. The line ratios of this ionized gas are frequently used to characterize the ionization conditions. We use the Hii regions catalogue from the CALIFA survey (~5000 H ii regions), to explore their distribution across the classical [OIII]/Hbeta vs. [NII]/Halpha diagnostic diagram, and how it depends on the oxygen abundance, ionization parameter, electron density, and dust attenuation. We compared the line ratios with predictions from photoionization models. Finally, we explore the dependences on the properties of the host galaxies, the location within those galaxies and the properties of the underlying stellar population. We found that the location within the BPT diagrams is not totally predicted by photoionization models. Indeed, it depends on the properties of the host galaxies, their galactocentric distances and the properties of the underlying stellar population. These results indicate that although H ii regions are short lived events, they are affected by the total underlying stellar population. One may say that H ii regions keep a memory of the stellar evolution and chemical enrichment that have left an imprint on the both the ionizing stellar population and the ionized gasComment: 18 pages, 8 figures, accepted for publishing in A&