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The primary objective of this paper is to develop a hybrid grey box model that integrates air and thermal dynamics to improve accuracy in both domains. The methodology involved developing four grey box models to estimate ventilation airflows using indoor CO2 concentration data and six thermal models to estimate thermal properties and heat gains using indoor temperature data. To ensure accurate parameterization, measurements of outdoor conditions, occupancy, and HVAC operations were incorporated. The results revealed that models treating infiltration and mechanical ventilation as mutually exclusive (IAQ-3 and IAQ-4) and those integrating ventilation heat gains from estimated airflows (T-6) performed most effectively. This hybrid approach underscores the benefits of incorporating ventilation heat loos or gains, based on airflow estimation derived from indoor air quality (IAQ) models, into thermal modelling, significantly improving accuracy and reducing parameter variability. The findings demonstrate the potential of this methodology for applications in ventilation management and HVAC optimization. By enhancing energy efficiency and improving indoor air quality, this approach supports the development of healthier, more sustainable indoor environments. This research was supported by a predoctoral contract grant (reference no. PRE2021-099606) as part of the research and development project IAQ4EDU (reference no. PID2020-117366RB-I00), funded by MCIN/AEI/10.13039/501100011033/FEDER, and is part of the project BINAFET (reference no. TED2021-130047B-C22), funded by MCIN/AEI/10.13039/501100011033 and by the European Union “NextGenerationEU”/PRTR. Moreover, this study was supported by the Catalan agency AGAUR through its research group support programme (2021 SGR 00341).

AbstractTomato residues are a form of solid waste that can be converted into methane through anaerobic digestion (AD). However, methane production is often limited due to incomplete hydrolysis caused by the high lignocellulosic content of tomato waste. Enzymatic pretreatments represent a promising approach to enhance methane yields by facilitating substrate hydrolysis. This study evaluated four commercial enzymatic blends – Celluclast 1.5 L, Maxoliva HC L, Viscozyme, and Novozym 435 – using biomethane potential (BMP) tests with two operational strategies: (i) preincubation of enzymes with tomato waste prior to AD, and (ii) direct addition of enzymes to the anaerobic digester. Maxoliva achieved the highest methane yield (348 ± 20 mL CH4 g−1 volatile solids (VS)) under preincubation, representing 99.5% of the theoretical BMP and a 90% increase in comparison with the control. Kinetic analysis using the modified Gompertz equation revealed that Maxoliva also exhibited the highest maximum methane production rate (RMAX = 5.5 ± 0.2 mL CH4 g−1 VS day−1) with direct addition. Conversely, Viscozyme showed limited effectiveness, reaching only 47% of the theoretical BMP value. The enhanced methane production observed with certain enzymatic blends is likely attributable to cellulase activity, which facilitates the breakdown of complex carbohydrates into easily biodegradable polysaccharides.

La transició dels sistemes energètics cap a tecnologies energètiques renovables amb baixes emissions de carboni és una mesura clau per mitigar el canvi climàtic. La Unió Europea (UE) ha establert l’objectiu d’aconseguir una reducció d’emissions de gasos d’efecte hivernacle (GEH) del 80% al 95% l’any 2050. El biogàs ha demostrat tenir un potencial important com a font d'energia renovable per a aplicacions industrials i domèstiques i una solució eficient a la crisi energètica global. També pot ajudar a resoldre el problema de la gestió de residus en convertir els materials orgànics de rebuig en energia, i reduir l’ús d’abocadors i les emissions associades de metà, un potent gas d’GEH. Aquest projecte es centra en l’avaluació ambiental de les emissions GEH associades a la producció de biometà liquat en una planta de gestió i producció de biogàs. La metodologia que s’utilitza per calcular la petjada de carboni de la planta és l’Anàlisi del Cicle de Vida (ACV) segons les normatives ISO 14040-44:2006, i la normativa relativa al càlcul de la petjada de carboni de producte ISO 14067:2019. A més, l’avaluació ambiental també inclou el criteri de tall o “Cut-off” per ometre etapes de cicle de vida no rellevants, tipus d’activitats, processos i productes específics; i la metodologia d’aplicació de crèdits o metodologia de càrrega evitada, que consisteix en comptabilitzar com crèdits les emissions que es deixen d’emetre en la producció de biometà en lloc de produir metà d’origen fòssil. Per altra banda, els resultats obtinguts de l’ACV es contraposen amb dades provinents d’eines de càlcul d’emissions de CO2 així com estudis científics rellevants en el camp del biogàs, amb l’objectiu de validar els resultats.

Abstract The aim of this study is to evaluate the incremental innovation performance of nuclear energy projects. Within this context, a novel model is generated which consists of two different stages, and large nuclear reactors are taken into consideration. Firstly, the Pythagorean fuzzy DEMATEL is used to weight the phases of technology S-Curve for nuclear energy projects. Moreover, the second stage includes the ranking two-generation technology S-curve with integer patterns for nuclear energy projects. In this framework, the best combinations are selected for innovation life cycle pattern with the integer code series. The findings demonstrate that the nuclear energy companies need to consider the two-generation technology S-Curve because continuous technological developments are occurring for nuclear power generation. It is also determined that aging in the first generation is the most significant period of two-generation technology S-Curve for nuclear energy projects. In this process, critical decisions should be made regarding future technological investments. In addition, the growth phase in the second generation is also important for the effectiveness of the nuclear energy technology. Conducting effective evaluations in these processes will contribute to increasing the efficiency of companies.

With the increasing demand for clean and renewable energy sources, the need for reliable offshore wind technologies is undeniable. Given the elevated costs of maintenance at sea, it is crucial to ensure the proper functioning of each of the components of the machine, therefore, proper validation is essential. This thesis presents a methodological approach on the validation of one of the actuators from the yaw system, responsible of keeping the turbine facing the wind at all times. Each actuator is comprised of an electric motor and a variable frequency drive (VFD), which have been tested in a back-to-back test bench, property of GE VERNOVA. First, two small motors have been evaluated to obtain their internal parameters and familiarise with the tools and procedures. Then, two 7.5 kW motors have been studied to ensure that they are capable for implementation in the wind turbine, and they have been compared to find the better candidate. The results have shown that the Bonfiglioli BE160M seems to present better features that the Nord 160M/6CUS in terms of torque capabilities, efficiency, and size. Nevertheless, more testing is desired to corroborate the results. In conclusion, opting for the Bonfiglioli motor could potentially improve the performance of the GE VERNOVA offshore turbines. As future work, it would be interesting to support the findings by simulating real wind loads on the back-to-back test bench and analysing thermal properties of each motor.

Moisture availability is a strong determinant of decomposition rates in forests worldwide. Climate models suggest that many terrestrial ecosystems are at risk from future droughts, suggesting moisture limiting conditions will develop across a range of forests worldwide. The impacts of increasing drought conditions on forest carbon (C) fluxes due to shifts in organic matter decay rates may be poorly characterised due to limited experimental research. To appraise this question, we conducted a meta-analysis of forest drought experiment studies worldwide, examining spatial limits, knowledge gaps and potential biases. To identify limits to experimental knowledge, we projected the global distribution of forest drought experiments against spatially modelled estimates of (i) future precipitation change, (ii) ecosystem total above-ground C and (iii) soil C storage. Our assessment, involving 115 individual experimental study locations, found a mismatch between the distribution of forest drought experiments and regions with higher levels of future drought risk and C storage, such as Central America, Amazonia, the Atlantic Forest of Brazil, equatorial Africa and Indonesia. Decomposition rate responses in litter and soil were also relatively under-studied, with only 30 experiments specifically examining the potential experimental impacts of drought on C fluxes from soil or litter. We propose new approaches for engaging experimentally with forest drought research, utilising standardised protocols to appraise the impacts of drought on the C cycle, while targeting the most vulnerable and relevant forests.

[eng] Developing advanced and efficient electrocatalytic energy conversion systems is of great and practical significance for propelling the efficient development of clean energy for the construction of new low-carbon power systems. Among them, electrocatalytic reduction reactions driven by renewable electricity to transform biomass-derived chemicals into biofuels and high value-added chemicals provide an effective way to improve the H/C ratio of biomass-derived chemicals and the stabilizations of bio-oil systems. However, the electrocatalytic reduction of organic compounds is more intricate compared to the electrocatalytic reduction of water molecules. It involves the adsorption of various organic functional groups, multi-step electron transfer, and the generation of organic intermediates. Meanwhile, organic electrocatalytic reduction calls for designing efficient, highly selective, and cost- effective electrocatalysts. During a series conversion process of raw biomass, aldehydes are believed to be particularly troublesome for the aldol condensation and polymerization reactions. To avoid them, hydrogenation processes are necessary. As an alternative to traditional high-pressure and -temperature processing, we choose electrochemistry that can operate in ambient conditions for the conversion of benzaldehyde (BZH), which was chosen as a typical biomass-derived chemical. Another reason for choosing BZH is that the hydrogenation products benzyl alcohol (BA) and hydrobenzoin (HDB) are important industrial chemicals. Based on the mentioned above, this work seeks to design highly efficient and high selective catalysts for the electrocatalytic conversion of the carbonyl group of BZH into BA, HDB or benzoic acid (BZA) in aqueous solution at pH＞5 (avoiding the deoxygenation product toluene). Additionally, this work screens the optimal reaction conditions for various products and speculates their most probable reaction pathways. Chapter 4 focused on the electrocatalytic reduction of BZH into BA. Pd nanoparticles supported on a nickel metal-organic framework (MOF), Ni-MOF-74, are prepared and their activity towards the ECH of BZH in a 3M sodium acetate-acetic acid (pH 5.2) aqueous electrolyte is explored. An outstanding ECH rate up to 283 µmol cm-2 h-1 with a Faradic efficiency (FE) of 76% is reached. Besides, higher FEs of up to 96% are achieved using a step-function voltage. Materials studio and density functional theory calculations show these outstanding performances to be associated with the Ni- MOF support that promotes H-bond formation, facilitates water desorption, and induces a favorable tilted BZH adsorption on the surface of the Pd nanoparticles. In this configuration, BZH is bonded to the Pd surface by the carbonyl group rather than through the aromatic ring, thus reducing the energy barriers of the elemental reaction steps and increasing the overall reaction efficiency. Chapter 5 focused on the electrochemical reduction of self-coupling of BZH to HDB using semiconductor electrocatalysts with nanosheet morphologies. The effects of electrode potential and electrolyte pH on BZH self-coupling reaction were comprehensively studied on several semiconductor electrocatalysts. A correlation is observed between their band gap and the electrochemical potential necessary to maximize selectivity towards HDB in alkaline medium, which we associate with the charge accumulation at the semiconductor surface. N-type CuInS2 provides the highest conversion rate at 0.3 mmol cm−2 h−1 with a selectivity of 98.5% at -1.3 V vs. Hg/HgO in aqueous alkaline solution pH=14. Additional density functional theory calculations demonstrate a lower kinetic energy barrier at the CuInS2 surface compared with graphitic carbon, proving its catalytic role in the self-coupling reaction of BZH. Based on the previous two works, we realize that even when selecting materials with poor HER performance, different voltages and pH values have a significant impact on the selectivity of HDB. This drives us towards the rational design of electrocatalysts for these two different reaction pathways. Chapter 6 employed material with exposed active sites Cu2S and the material Cu2S-OAm with ligands capped to catalyze the electrocatalytic reduction reaction of the biomass platform molecule BZH convert into BA and HDB. Cu2S particles are used as electrocatalysts for the BZH electrochemical conversion. We particularly analyze the effect of surface ligands, oleylamine (OAm), on the selective conversion of BZH to BA or HDB. The effect of the electrode potential, electrolyte pH, and temperature are studied. Results indicate that bare Cu2S exhibits higher selectivity towards BA, while OAm-capped Cu2S promotes HDB formation. This difference is explained by the competing adsorption of protons and BZH. During the BZH electrochemical conversion, electrons first transfer to the C in the C=O group to form a ketyl radical. Then the radical either couples with surrounding H+ to form BA or self-couple to produce HDB, depending on the available H+ that is in turn affected by the electrocatalyst surface properties. The presence of OAm inhibits the H adsorption on the electrode surface therefore reducing the formation of high-energy state Had and its combination with ketyl radicals to form BA instead promotes the outer sphere reaction for obtaining HDB. Finally, we turn our attention to the anodic reaction in chapter 7. The electrooxidation of organic compounds offers a promising strategy for producing value-added chemicals through environmentally sustainable processes. A key challenge in this field is the development of electrocatalysts that are both effective and durable. In this study, we grow gold nanoparticles (Au NPs) on the surface of various phases of titanium dioxide (TiO2) as highly effective electrooxidation catalysts. Subsequently, the samples are tested for the oxidation of BZH to BZA coupled with a hydrogen evolution reaction (HER). We observe the support containing a combination of rutile and anatase phases to provide the highest activity. The excellent electrooxidation performance of this Au-TiO2 sample is correlated with its mixed-phase composition, large surface area, high oxygen vacancy content, and the presence of Lewis acid active sites on its surface. This catalyst demonstrates an overpotential of 0.467 V at 10 mA cm-2 in a 1 M KOH solution containing 20 mM BZH, and 0.387 V in 100 mM BZH, well below the oxygen evolution reaction (OER) overpotential. The electrooxidation of BZH not only serves as OER alternative in applications such as electrochemical hydrogen evolution, enhancing energy efficiency, but simultaneously allows the generation of high-value byproducts such as BZA [spa] El desarrollo de sistemas de conversión de energía electrocatalítica avanzados es crucial para la energía limpia y un sistema energético de bajo carbono. La reducción electrocatalítica de productos químicos de biomasa mejora la relación H/C y estabiliza los aceites biológicos, aunque es compleja debido a la transferencia de electrones y generación de intermediarios. Es esencial diseñar electrocatalizadores eficientes y selectivos. La hidrogenación de aldehídos en la biomasa cruda es necesaria para evitar reacciones no deseadas. Se utilizó la electroquímica para convertir benzaldehído (BZH) en productos industriales valiosos como alcohol bencílico (BA) e hidrobencoína (HDB). Este trabajo diseñó catalizadores eficientes para convertir BZH en BA, HDB o ácido benzoico (BZA) en solución acuosa con pH ＞ 5, optimizando las condiciones de reacción. En el Capítulo 4, se usaron nanopartículas de Pd en un marco metal-orgánico de níquel (Ni-MOF-74) logrando una alta eficiencia faradaica (FE) y mejor adsorción de BZH. El Capítulo 5 estudió el acoplamiento de BZH a HDB con electrocatalizadores semiconductores, destacando el CuInS₂ de tipo N por su alta selectividad y eficiencia. En el Capítulo 6, se usaron partículas de Cu₂S con y sin oleylamine (OAm), mostrando que OAm promueve la formación de HDB al inhibir la adsorción de protones. El Capítulo 7 se enfocó en la electrooxidación de BZH a BZA usando nanopartículas de oro (Au NPs) en dióxido de titanio (TiO₂), logrando alta actividad y eficiencia energética, generando además subproductos valiosos. Programa de Doctorat en Electroquímica. Ciència i Tecnologia