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Chemical looping combustion allows the carbon dioxide capture by using an oxygen carrier, which transports the oxygen required for combustion from the air to the fuel. But complete combustion of a solid fuel is not achieved when low cost materials were used as oxygen carriers. Manganese‑iron mixed oxide doped with titanium has been identified as a promising oxygen carrier to improve combustion efficiency due to its oxygen uncoupling capability. The objective of this work was to assess the potential of this oxygen carrier when burning coal in a chemical looping unit. The coal combustion efficiency and carbon dioxide capture were evaluated as a function of the operating conditions both in the fuel and air reactor. Carbon dioxide capture was affected by the solids residence time in the fuel reactor. Coal combustion efficiency increased as the oxygen uncoupling capability was enhanced by using suitable operating conditions in the air reactor. Almost full coal combustion (99.4%) was achieved by setting an air reactor temperature of 880 °C, an air excess of 1.8, a fuel reactor temperature of 925 °C, and an oxygen carrier to fuel ratio >3. The oxygen carrier showed magnetic properties, allowing its re-use after being separated from ash. This work was partially supported by the project ENE2016-77982-R (AEI/FEDER, UE) and project ENE2017-89473R (AEI/FEDER, UE), and by the Consejo Superior de Investigaciones Científicas (CSIC project: 2017-80E035). 10 Figures, 4 Tables.-- © 2019. This manuscript version is made available under the CC-BY-NC-ND 4.0 license http://creativecommons.org/licenses/by-nc-nd/4.0/ Peer reviewed

We present the results of the spectral transmittance and reflectance of a SiO2/TiO2 1D photonic crystal deposited by Radio Frequency sputtering on a flexible polymeric substrate, which shows a blue-shift in its transmittance stopband proportional to the incidence angle when bent. An adjustable sample holder was designed to regulate the bending and keep the sample in a bent condition. Different angles of incidence were also achieved through variable angle reflectance, where an increase in incidence angle led to the blue-shift and narrowing of the transmittance stopband. We addressed the sample's resistance against bending wear and tear by comparing the transmittance spectra acquired for the flat sample before and after the measurements made in bent configurations. An important stability has been observed.

While traditional methods for modelling the thermal and electrical behaviour of photovoltaic (PV) modules rely on analytical and empirical techniques, machine learning is gaining interest as a way to reduce the time, expertise, and tools required by designers or experts while maintaining high accuracy and reliability. This research presents a data-driven machine learning tool based on artificial neural networks (ANNs) that can forecast yearly PV electricity directly at the optimal PV inclination angle without geographic restrictions and is valid for a wide range of electrical characteristics of PV modules. Additionally, empirical correlations were developed to easily determine the optimal PV inclination angle worldwide. The ANN algorithm, developed in Matlab, systematically and quantitatively summarizes the behaviour of eight PV modules in 48 worldwide climatic conditions. The algorithm’s applicability and robustness were proven by considering two different PV modules in the same 48 locations. Yearly climatic variables and electrical/thermal PV module parameters serve as input training data. The yearly PV electricity is derived using dynamic simulations in the TRNSYS environment, which is a simulation program primarily and extensively used in the fields of renewable energy engineering and building simulation for passive as well as active solar design. Multiple performance metrics validate that the ANN-based machine learning tool demonstrates high reliability and accuracy in the PV energy production forecasting for all weather conditions and PV module characteristics. In particular, by using 20 neurons, the highest value of R-square of 0.9797 and the lowest values of the root mean square error and coefficient of variance of 14.67 kWh and 3.8%, respectively, were obtained in the training phase. This high accuracy was confirmed in the ANN validation phase considering other PV modules. An R-square of 0.9218 and values of the root mean square error and coefficient of variance of 31.95 kWh and 7.8%, respectively, were obtained.The results demonstrate the algorithm’s vast potential to enhance the worldwide diffusion and economic growth of solar energy, aligned with the seventh sustainable development goal.

In the Mediterranean regions, hydrologic processes are quite specific due to the temporal variability of precipitation characterized by a succession of drought and flash-flood periods. These processes may also have changed due to a range of human activities such as land use changes, dams building, soil and water conservations works. The Merguellil catchment (Central Tunisia) is a typical Mediterranean semi-arid basin which suffers regular water shortage aggravated by current drought. It extends on an area of about 1200 km² upstream of the El Houareb dam which presents its outlet. This semi-arid zone is exposed to a high variability of rainfall in time and space. Annual means vary between 300 mm in the plain and 500 mm in the highest parts. During the recent decades the continuous construction of small and large dams and Soil and Water Conservation Works (SWCW) (ie. Counter ridges) has taken place within the watershed. These practices, that currently cover nearly of the basin surface, are classified in two categories: the practices on basin slopes constituted essentially by contour ridges (200 Km²) and the practices on the hydrographical network by implantation of small hilly dams draining about 170 Km. These water harvesting systems may intercept runoff at the upstream part of the catchment, thus depriving potential downstream users of their share of the resources. However, little is known about the effect of these water harvesting systems on the water balance components of arid watersheds. In such a vulnerable situation of water resources availability, it can be expected that the impact of climate change will further worsen the situation. The work presented here attempts to simulate the actual water and nutrient balance using the integrated hydrological model “Soil and Water Assessment Tool” (SWAT 2005). The simulation results revealed that vapotranspiration is the major component of the hydrological balance. Hydrological Calibration (1992-1994) and validation (1998) have been carried out referring to daily flow data at the Hafouz and Skhira flow-gauges. The model performance was satisfactory and the Nash-Sutcliffe Efficiency coefficient ranges from 0.6 to 0.7. The model was rather successful in reproducing water flow. However the low sampling frequency and the lack of detailed water quality measurement data did not allow an in-depth evaluation of the SWAT performance in predicting nutrient and sediment. Some scenarios were further generated. The first one regards the removal of contour ridges to assess their impact to water and sediment load. The results show that the contour ridges contribute to the retention of high quantity of sediment. These regulations reduce the surface runoff by 32 %. Planting the olive trees between contours could improve its yield. The second scenario consists in the reduction of the applied fertilizers. By reducing 20% in the applied fertilizers no change was detected in the olive yield, while a small change was noted for durum wheat yield’s (-2%). Whereas a net decrease in nutrient load was observed at the outlet. This reduction ranges, from 3 to 10% for nitrates, from 2.5 to 8% for total nitrogen and from 13 to 16.5 % for total phosphorus. Finally, the SWAT model was used to study the impact of future climate on water resources of this Mediterranean catchment. Future climate scenarios for periods of 2010-2039 and 2070- 2099 were generated from the Canadian Global Coupled model (CGCM 3.1) for scenarios A1B, B1, and A2. These CGCMs data were then statistically downscaled to generate future possible local meteorological data of precipitation and temperature in the study area. SWAT model was run first under current climate (1986-2005) and then for the future climate period to analyze the potential impact of climate change on flow, evapotranspiration, and soil moisture across this catchment. Finally, Richter et al.’s Indicators of Hydrologic Alteration (IHA) were used to analyze the flow regime alterations under changing climate. The main results indicate that this catchment would suffer a combination of increased temperature and reduced rainfall that will reduce water resources in this area. Consequently, summer droughts would be intensified. Different spatial responses to climate change were observed in the catchment for near future simulations. Higher altitude regions would experience an increase of the total water yield, while a reduction is foreseen for lower parts. For far future, a noticeable decrease would affect water resources in all part of the catchment. Nelle regioni del Mediterraneo, i processi idrologici sono caratterizzati dalla variabilità temporale delle precipitazioni che si manifesta attraverso la successione di periodi di siccità e allagamenti. L’alterazione dei processi idrologici nell’area del Mediterraneo è attribuibile, oltre che alle alterazioni climatiche globali, anche alla pressione antropica sul territorio attraverso la modificazione dell’uso del suolo, la costruzione di sbarramenti fluviali e le opere di protezione idraulica e del suolo. Il bacino idrografico di Merguellil (nella Tunisia centrale) è un tipico bacino semi arido del Mediterraneo caratterizzato da un deficit idrico aggravato dagli attuali eventi siccitosi. L’area è contraddistinta da un’elevata variabilità delle precipitazioni nello spazio e nel tempo. In particolare, la media annuale di precipitazione varia tra 300 mm nelle aree di pianura e 500 mm in quelle più alte. Nel corso degli ultimi decenni il bacino è stato interessato dalla costruzione di dighe e le opere di protezione idraulica e del suolo. Queste pratiche, che attualmente ricoprono il 25% della superficie del bacino, si distinguono in due categorie di interventi: quelle che interessano i versanti del bacino, essenzialmente fossi di guardia e terrazzamenti (200 km2), e quelle che insistono sul reticolo idrografico attraverso la costruzione di sbarramenti (170 km). Questi sistemi di raccolta dell’acqua intercettano il ruscellamento superficiale della parte più elevata del bacino, privando la parte bassa di una cospicua aliquota d’acqua. Tuttavia, l’effetto di questi interventi di sistemazione idraulica sulle componenti del bilancio idrico dei bacino aridi è poco conosciuto. In tale situazione di vulnerabilità delle risorse idriche, ci si attende che l’impatto dei cambiamenti climatici peggiori la situazione. Il presente lavoro ha lo scopo di modellare le risorse idriche attuali e il bilancio dei nutrienti nel bacino di Merguellil utilizzando il modello idrologico integrato “Soil and Water Assessment Tool” (SWAT, 2005). I risultati delle simulazioni rivelano che l’evapotraspirazione è la principale componente del bilancio idrologico. La calibrazione idrologica (1992-1994) e la validazione (1998) è stata condotta riferendosi ai dati giornalieri di portata delle stazioni idrolometriche di Hafouz e Skhira. La performance del modello è stata soddisfacente ottenendo un coefficiente di efficienza di Nash-Sutcliffe che varia tra 0.6 e 0.7. Il modello ha riprodotto correttamente le portate. Tuttavia la bassa frequenza di campionamento e la carenza di misure dettagliate di qualità dell’acqua non hanno permesso di valutare approfonditamente le performance di SWAT nel simulare il carico di nutrienti e sedimenti. Sono stati generati alcuni scenari. Il primo scenario riguarda la rimozione dei fossi di guardi per valutare il loro impatto sul carico idraulico e dei sedimenti. Queste regolazioni riducono il ruscellamento superficiale del 32%. La piantumazione di alberi di ulivo tra i fossi di guardia potrebbe migliorare la resa. Il secondo scenario consiste nella riduzione dei fertilizzanti utilizzati. Attraverso la riduzione del 20% del quantitativo dei fertilizzanti nessun cambiamento della resa degli ulivi è stato osservato, mentre un ridotto cambiamento è stato osservato nella resa del grano duro (-2%). Invece una netta diminuzione nel carico di nutrienti è stata osservata all’uscita. Questa riduzione varia dal 3% al 10% per i nitrati, dal 2.5% all’8% per l’azoto e dal 13% al 16.5% per il fosforo totale. Infine, il modello SWAT è stato utilizzato per lo studio di impatto del clima futuro sulle risorse idriche del bacino idrografico. Gli scenari climatici futuri per il periodo 2010-2039 e 2070-2099 sono stati generati dal modello accoppiato globale canadese CGCM 3.1 per gli scenari di emissione A1B, B1, e A2. I dati del modello climatico CGCM sono stati sottoposti ad una procedura di downscaling statistico per generare scenari locali di precipitazione e temperatura dell’area di studio. Il modello SWAT è stato fatto girare prima in condizioni climatiche attuali (1986-2005) e poi in condizioni di cambiamento climatico futuro per analizzare l’impatto potenziale dei cambiamenti climatici sulla portata, evapotraspirazione ed umidità del suolo del bacino in esame. Infine, per analizzare le alterazioni del regime di portata sono stati utilizzati gli indicatori dell’alterazione idrologica (Indicators of Hydrologic Alteration –IHA) di Richter et al. I risultati principali indicano che nel bacino studiato, l’azione combinata dell’ incremento di temperatura e riduzione della precipitazione, porterà alla riduzione delle risorse idriche. Gli effetti del cambiamento climatico sulle risorse idriche del bacino non sono univoci per tutta l’area, ma si differenziano in base alle caratteristiche topologiche del territorio. Le regioni ad alte altitudine subiscono un incremento del tasso totale d’acqua, mentre per le parti basse si prospetta una riduzione. Per l’ultimo trentennio del secolo, invece una pesante diminuzione delle risorse idriche influenzerà tutte le parti del bacino. Dottorato di ricerca in Scienze e tecnologie per la gestione forestale e ambientale

Abstract Building energy performance requirements aiming at the nZEB target have been recently established by the national legislation. In Italy, the requirements are verified through the notional reference building, whose U-values are reduced in two steps: up to 2018 and since 2019 for public buildings, and up to 2020 and since 2021 for all other buildings. This might cause a reduction of the heating need but an increase of the cooling need. The objective of the study is to investigate in which conditions and extent a significant imbalance of the energy needs occurs. Different building types and climatic zones are considered.

[EN] Many governments are pushing for cleaner transportation. In particular, public transportation allows massive transportation of passengers, but it remains highly polluting, especially in high elevation cities. Thus, the progressive introduction of electric buses (EBS) will allow mitigating these environmental concerns. However, some technological problems must be addressed considering the massive penetration of EBs. The lack of flexibility and the time connection of scheduling for public transit make EBS harder than internal combustion ones. This work studies the impact of charging EBs at the bus station and suggests a new way to take EB aggregators into account to reduce energy costs while fulfilling grid restrictions. In addition, to find a different number of charging spots to be installed, a scheduling analysis is conducted. This works belongs to the projects IEA.JCG.20.01 and SIS.MGR.21.01 from Universidad de las Americas - Ecuador. The authors would like to thank Paulo Guerra-Teran from Universidad de las Americas - Ecuador for the fruitful discussion.

Eggshell is a cheap and environmentally friendly waste stream from the food industry, which could be potentially used for different applications in a circular economy scenario. Carbonation of eggshell derived sorbents has been investigated for calcium looping high temperature applications. Nevertheless, the application of these sorbents for direct air capture is yet to be explored in detail. In this work, waste eggshell (ES) and three different ethanol/water treated eggshell samples (E70, E80 and E90) are assessed for direct air capture and compared to limestone. These samples are exposed to ambient air in two distinct conditions. Namely, i) ambient air at 25 °C in a laboratory and ii) refrigerator conditions at 4 °C in order to simulate how these sorbents might perform in different climatic scenarios for varying geographic areas. Carbonation and hydration conversions were calculated for times of ∼ 3000 h. It was found that treating the eggshells with ethanol was key in order to obtain a suitable material for this application. Two of the ethanol-treated samples obtained similar conversions in comparable amounts of time for ambient air conditions, while limestone still performed better in refrigerator conditions