El texto completo de este trabajo no está disponible en el Repositorio Académico UPC por restricciones de la casa editorial donde ha sido publicado. / The recent climate change has forced people to live in extreme conditions, either excessive heat or cold, implying that they must adapt to survive in these situations. However, there are people who, because of their geographical condition and lack of resources, lack the means and tools to combat these climate changes. The context of this study is provided in a rural town located in the Arequipa region (Peru), whose inhabitants have to fight against frosts of up to −20 °C in an area without electricity. A viable solution to this problem is found through the design and implementation of a heating system using geothermal and photovoltaic energy, which are resources found in the area, according to a report of the Ministry of Energy and Mines. This study analyzes and researches the geographical and meteorological conditions of the region, for validating, through theory and simulations, whether the proposed system can supply the thermal energy required to maintain the indoor temperature at a minimum of 15 °C under extreme conditions. The system is designed after analyzing the best technological options and techniques currently available in the context studied for its ultimate financing and establishing guidelines and indicators for monitoring results.

>Magister Scientiae - MSc / The global dependence on non-renewable fossil fuels to meet energy needs cannot be sustained for a long time and it is already evident in the escalation of fuel prices over the past decade. This research was performed towards renewable energy production from agricultural and food waste. The use of agricultural and food waste has benefits such as being grown in a land that is not in competition with food crops protein, all year round availability, and having high lipid content. The produced bio-crude oil can be upgraded to remove moisture and acidity level, and can be used as a substitute for heavy oils such as diesel to power static appliances or can be used as petrol distillate fuel alternative. Hydrothermal liquefaction (HTL) process is one of the commonly used technologies for converting agricultural and food waste into liquid biofuels.

Having been a hot topic for some time, the interest in recycling carbon dioxide to renewable liquid fuels or other valuable chemicals has rocketed since the adoption of the Paris Agreement on Climate Change. This is due to the EU ruling that from 2020, a considerable fraction of renewable fuel of non-biological origin has to be added to gasoline and the commitment of large air carriers like UA to go 50% carbon neutral by 2050. The primary novelty of this thesis was the development and conversion of the thermal catalyst indium oxide to an electrocatalyst that could do the conversion of formic acid and CO2 at ambient conditions with water as the only hydrogen source and the second starting compound. Here, the synthesis of indium oxide (In2O3) and supported iridium oxide (IrO2) electrocatalysts were done in-house. The crystallinities and average particle size characterizations were examined via powder X-ray diffraction. Scanning electron microscopy was used to study the surface morphologies of both electrocatalysts. Three different anodic electrocatalysts including 60:40 wt% IrO2:TaC, 70:30 wt% IrO2:TaC and 100:00 wt% IrO2:TaC were fabricated and employed for water electrolysis, with 70:30 wt% IrO2:TaC demonstrated to be of superior electrochemical activity and further employed for subsequent studies. Currently, In2O3 is the best thermal catalyst for methanol formation from CO2 . Here, the as-synthesized thermal catalyst was converted to a cathodic electrocatalyst by firstly making electroconductive material in a nanosize form with very small crystallite grains, which contain numerous defects near the surface; thus, making it more conductive. This was used to prepare high-performance membrane electrode assemblies (MEAs). The reaction cell containing the MEA that was set up by spray-coating the respective catalyst inks onto either Nafion® or a carbon gas diffusion cloth. The PEM electrolysis cell configuration with Nafion® as the polymer electrolyte was used. It minimizes Ohmic losses, and a standard TaC-supported IrO2 water-splitting catalyst served as the anode, titanium mesh served as anodic gas diffusion layer, and the experiments were conducted at ambient temperature. The cathode consisted of In2O3 spray-coated on carbon paper which acts as a gas diffusion layer and titanium mesh current collector. The cathode electrocatalyst was enhanced by the addition of a small amount of polytetrafluoroethylene to the nanosized In2O3 to facilitate diffusion of FA and CO2. The electrochemical characteristics were examined via cyclic voltammetry, linear sweep voltammetry and chronoamperometric methods. The infrared spectroelectrochemical cell was also used because it permits in-situ analysis of the change of reactant concentrations and ideally the identification of intermediates Addition of PTFE to the In2O3 electrocatalyst layer for FARR has led to significant improvement in current density from 1.94 mA/cm2 (without PTFE) to 66.0 mA/cm2 (with 0.15 wt% PTFE) and 70.3 mA/cm2 (with 0.30 wt% PTFE) which is a factor of ca. 34 and ca. 36 respectively at 2.4 V cell voltage. This further reduces the onset potential of the electroreduction by 0.4 V and notably, the cell Ohmic resistance was reduced by a factor of 15, implying that the activation energy of the electrode and the transport resistance in the porous structure are significantly reduced. This is due to the increase in the hydrophobicity in the porous electrocatalyst layer. The Tafel slope was also used to investigate the electrochemical reaction of water splitting, co-electrolysis of 4.30 M formic acid and water on In2O3 and PTFE-In2O3 cathodes. Tafel values of all the samples over the respective number of LSV cycles were consistent with each other. Tafel analysis of the PTFE-In2O3 electrode improves significantly with the lower Tafel slope in comparison with the PTFE-free In2O3 electrode. The steady-state current density experiment in the absence of any flow showed excellent stability over the investigation period. A current density observed to be limited to ca. 26 mA/cm2 in the absence of any flow over 24 h from the initial current density of 70.3 mA/cm2, the limitation is a result of FA transport across the diffusion layers in the electrocatalyst surface. This behavior was further investigated using the Cottrell equation and this was observed to qualitatively reproduce the experimental behavior, thereby confirming a diffusion layer that builds up, resulting in a reactant depletion near the electrode surface. For a long time, it was thought that formic acid is a dead-end that does not lead to larger product molecules. For the first time, the co-electrolysis of water and aqueous 4.30 M formic acid, the first stable intermediate of CO2 electroreduction, results in a mixture of methanol, ethanol and isopropanol with a maximum combined Faraday efficiency of 82.6% at 3.5 V and a space-time-yield of 0.431 g(alcohol)/h/g(cat) that compares well with results from heterogeneous catalysis. It was further discovered here that high Faraday efficiency of the alcohols and current density can be achieved under a relatively low overpotential by tuning the amount of PTFE used. FTIR spectroelectrochemistry was used to monitor the disappearance of FA and the formation or disappearance of CO2 reaction intermediates as a function of time and potentials. The consumption of FA propelled significant decreasing of absorption of up to 6 vibrational modes in the observation window including bands: at 3670 cm-1 belonging to the O-H stretching vibration, 3037 cm-1 assigned to the C-H stretching mode, 2120 cm-1 attributed to the C=O stretching mode, a double band near 1667/1589 cm-1, assigned to the vibrational modes with major FA C-O stretching character, and finally one at 1225 cm-1 which are somewhat higher than corresponding literature values, suggesting interactions with the catalyst and the presence of the aqueous environment. In the experiment performed with CO2 catholyte on PTFE-In2O3 (in the absence of FA), the CO2 band disappears as expected with no FA build-up, suggesting that formic acid is bypassed as an intermediate. An additional convincing difference was that while R/R0 is >1 dominated by the FA disappearance and CO2 formation in FA catholyte, it is <1 in CO2 catholyte, and the spectra revealed the CO2 disappearance with the formation of intermediates and products; seen as a broad structured background. The CO2 band changes in the positive direction, demonstrating that CO2 is used up with the applied potential going more negative. The CV experiments further established a cross-over oxidation peak which indicates multiple redox species or a multi-step parallel or consecutive mechanism with the PTFE-In2O3 cathode. This was due to the slow formation of redox-active intermediates and slow follow-up reactions occurring in the diffusion layer on the surface of the electrode. This further indicates that the appropriate amount of PTFE in the In2O3 catalyst layer would enhance the adhesion properties of the In2O3 catalyst layer on the carbon paper and create the hydrophobic channels in the catalytic layers. Finally, in agreement with the cyclic voltammetry, spectroelectrochemistry and electrolysis experiments, a plausible reaction mechanism for FA reduction to methanol on In2O3 cathode was proposed while the higher alcohols (i.e. C2 and C3 alcohols) may be formed through the same stepwise reduction pattern involving the different intermediate species formed. Therefore, this study established that the In2O3 electrocatalyst could do the conversion of formic acid (HCOOH) and CO2 at room temperature and with water in place of hydrogen as the second starting material in contrast to the known methods which were achieved at elevated temperatures. Importantly, the addition of PTFE facilitated FA and CO2 diffusion and enhanced the electrochemical performance of the In2O3 electrocatalyst. / Thesis (PhD (Chemistry))--University of Pretoria, 2020. / National Research Foundation and the World Academy of Sciences (NRF-TWAS): (UID: 105453 & Reference: SFH160618172220) National Research Foundation (NRF) S&F - Extended Support for Scholarships and Fellowships: (Reference No: MND190603441389, Unique Grant No: 121108) / Chemistry / PhD (Chemistry) / Unrestricted

Utilization of woody biomass for energy is expected to increase rapidly and logging residues are a likely feedstock to meet increased demands. Potentials for increased biomass utilization have created concerns regarding possible impacts of using logging residues for energy. The overall goals of this project were to characterize biomass harvesting operations and to evaluate potential impacts on soil erosion and implementation of Best Management Practices (BMPs) for water quality on biomass harvesting sites. Results indicate that biomass harvesting was integrated into a wide range of logging businesses. Existing biomass harvesting businesses reported total production levels ranging from 6 to 250 loads per week. The majority (98%) of biomass harvesting operations utilized integrated harvesting techniques where roundwood and fuel chips were produced concurrently. Potential erosion rates and BMP implementation scores were evaluated on ten biomass and ten conventional harvest sites in the Piedmont of Virginia. This study of 20 sites found no significant differences in overall estimated erosion rates between biomass harvests (0.7 tons ac-1 yr-1) and conventional harvests (0.8 tons ac-1 yr-1) (p=0.8282). Additionally, there were no significant differences observed in overall BMP implementation scores for biomass (85.2%) and conventional (81.3%) harvests (p=0.5930). A separate, but related study evaluated BMP implementation over a three year period on 88 biomass and 284 conventional harvests in the Piedmont of Virginia. Within the seven logging related BMP categories, only the Streamside Management Zones (SMZs) category had significant differences between biomass (83.1%) and conventional harvests (91.4%) (p=0.0010). Implementation score differences were not caused by insufficient residues for stabilization of bare soil but were apparently the result of operational decisions which resulted in lower implementation of BMPs related to SMZs. Overall, these findings indicate that existing BMPs appear adequate to protect water quality on biomass harvesting operations in the Virginia Piedmont when appropriately implemented. / Ph. D.

The world today is built on energy. Every process, whether industrial or civil, from the moment one awakes in the morning all throughout the day and into the late night, is fuelled by energy. There is an energy consumption going on twentyfour hours, every day of the year (IEA, 2017). The traditional energy mix (coal, gas, oil) has been used up to now with disrupting effects on our planet. In order to stay in the sustainable development concept, the demand for energy will be optimally met with renewable energies (RE), so to also keep the global temperatures under 2°C or even 1.5°C, if ambitious measures are used (IPCC, 2011).The focus of this study is on the Association of South East Nations (ASEAN), because it has an unexploited potential to increase the usage of RE, due the fact that the region has over 140 million in population without access the electricity (Shi, 2016, IEA, 2017). The region is also still developing its energy infrastructure and decides on energy road maps for the next couple of years (Zamora, n.d., Brahim, 2014, Alison Riddell, Steve Ronson, Glenn Counts, n.d., Renner et al., 2018). Thus, this is the right time to research why ASEAN has not yet implemented more RE into its nations.The paper will explore the experts perceptions on the RE implementations in ASEAN as well as how does the government regulation and policy structures involve in the renewable energy implementation. To provide a better understanding of the impacts in the implementation phase of RE in ASEAN, the PESTEL framework helps to analyse the area on a macro level from six different perspectives. This framework will also help to identify and give suggestions to overcome several obstacles that have emerged in the implementation of RE in ASEAN.

Wind and waves play a major role in important ocean dynamical processes, such as the exchange of heat, momentum and gases between atmosphere and ocean, that greatly contributes to the earth climate and marine lives. Knowledge on wind and wave weather and climate is crucial for a wide range of applications, including oceanographic studies, maritime activities and ocean engineering. Despite being one of the important world shipping routes, the wind-wave characteristics in the Red Sea are yet to be fully explored. Because of the scarcity of waves data in the Red Sea, numerical models become crucial and provide very powerful tools to extrapolate wind and wave data in space, and backward and forward in time. Unlike open oceans, enclosed basins wave have different characteristics, mainly because of their local generation processes. The complex orography on both sides of the Red Sea makes the local wind, and consequently wave, modeling very challenging. This thesis considers the modeling of wind-wave characteristics in the Red Sea, including their climate variability and trends using state-of-the-art numerical models and all available observations. Different approaches are investigated to model and understand the general and unusual wind and wave conditions in the basin using standard global meteorological products and customised regional wind and wave models. After studying and identifying the main characteristics of the wind-wave variability in the Red Sea, we demonstrate the importance of generating accurate atmospheric forcing through data assimilation for reliable wave simulations. In particular, we show that the state-of-the-art physical formulation of wave models is not suitable to model the unique situation of the two opposing wind-waves systems in the Red Sea Convergence Zone, and propose and successfully test a modification to the input and white-capping source functions to address this problem. We further investigate the climate variability and trends of wind and waves in the Red Sea using high-resolution wind and wave reanalyses that have been generated as part of this thesis. An innovative spectral partition technique is first applied to distinguish the dominant wave systems. Our analysis demonstrates that winds, and consequently waves, exhibit a decreasing trend in the Red Sea. This is mainly attributed to a remarkable weakening of the winds protruding from the Mediterranean Sea. We also use these highresolution reanalyses to assess the potential for harvesting wind and wave energy from the Red Sea.

Blended finance (“BF”) is a form of structuring finance which involves using foreign aid to leverage commercial funding to a project. The topic is generally under researched, despite its increased importance in development finance and as a tool in attaining the United Nations Sustainable Development Goals. This research set out to investigate if BF was being applied in a justified manner in private sector renewable energy (“RE”) projects in Sub-Saharan Africa (“SSA”). The first two sub-questions looked at the criteria considered when qualifying projects for BF, and the factors influencing terms offered. The final sub-question was to seek operational evidence of appropriate BF usage. Data was collected through a series of semi-structured interviews with Donors, Development Finance Institutions (“DFIs”) and research institutions and analyzed using an inductive thematic approach. A descriptive case study was used to answer the final sub-question, and involved interviews with key individuals involved with the BF approval process in the selected project. The results suggest that BF is being applied in a justified manner. Sub-question one found that there is a difference in the criteria considered by Donors and DFIs when offering BF. Donor principles appear to be broader, due to their limited engagement on individual projects and delegated investment authority to DFIs. Having a development rationale and economic case for the use of BF was a prominent theme with DFIs and Donors. Factors influencing the BF terms offered to projects were difficult to extract due to the sensitive nature of the topic. Four factors did emerge, with minimizing concessionality being an overarching theme. For the final sub-question, the Mocuba Solar project was used as a case study and provided much needed evidence on the detailed processes followed in assessing the projects need for BF and how terms were derived. This research sheds light on the project level use of BF in the SSA RE IPP context and identifies areas where improvements can be made. Having more BF case studies and an agreed definition of BF for reporting purposes were recommendations to ensure BF is applied effectively.

The way our electricity is generated is in a period of rapid change; in the United States and many other countries the system is becoming less reliant on coal based power systems, while natural gas and solar and wind power are becoming more and more important. Technological advances have made solar and wind power more efficient and increasingly cost-effective. While these changes to the electrical system come with great benefits, such as less pollution, these technologies are not free of impacts. The electrical system is inseparable from our modern lifestyle, and because the system is so large this transition will affect society in many ways. This dissertation analyzes one aspect of the social side of these changes in the electrical system by asking, what does the public think about renewable energy? In particular we examined how political beliefs, community differences, and residential distance from wind turbines might influence attitudes about renewable energy. We find that political belief is an important factor in predicting levels of support for renewable energy, with conservatives less likely to prefer renewable energy and liberals more supportive of its development. We also find distinct differences in how residents of particular communities tend to react to renewable energy and local wind power development. In addition, we find that living closer to wind turbines is not a good way to predict attitudes about wind energy. These results should help policy makers and developers to make better decisions about how and where we build utility-scale solar and wind electric power facilities by taking into consideration the nuances of personal and political beliefs as well as community differences.

Microalgae have many desirable attributes as a renewable energy recourse. These include use of poor quality land, high yields, and it is not a food recourse. This research focusses on the energetic and environmental impact of processing microalgae into a renewable diesel. Two thermochemical bio-oil recovery processes are analyzed, pyrolysis and hydrothermal liquefaction (HTL). System boundaries include microalgae growth, dewatering, thermochemical bio-oil recovery, bio-oil stabilization, conversion to renewable diesel, and transportation to the pump. Two system models were developed, a small-scale experimental and an industrial-scale. The small-scale system model is based on experimental data and literature. The industrial-scale system model leverages the small scale system model with scaling and optimization to represent an industrial-scaled process. The HTL and pyrolysis pathways were evaluated based on net energy ratio (NER), defined here as energy consumed over energy produced, and global warming potential (GWP). NER results for biofuel production through the industrial-scaled HTL pathway were determined to be 1.23 with corresponding greenhouse gas (GHG) emissions of -11.4 g CO2 eq (MJ renewable diesel)-1. Biofuel production through the industrial-scaled pyrolysis pathway gives a NER of 2.27 and GHG emissions of 210 g CO2 eq (MJ renewable diesel)-1. For reference, conventional diesel has an NER of 0.2 and GHG emissions of 18.9 g CO2 eq MJ-1 with a similar system boundary. The large NER and GHG emissions associated with the pyrolysis pathway are attributed to feedstock drying requirements and combustion of co-products to improve system energetics. Process energetics with HTL and pyrolysis are not currently favorable for an industrial scaled system. However, processing of microalgae to biofuel with bio-oil recovery through HTL does produce a favorable environmental impact and a NER which is close to the breakeven point of one.

La forte proportion des sources d'énergie intermittentes présente de nouveaux défis pour la stabilité et la fiabilité des réseaux électriques. Dans ce travail nous considérons la connexion de ces sources avec et un système de stockage hybride via un MicroGrid à courant continu (DC) afin de satisfaire les contraintes de connexion au réseau (les Grid-Codes). L'objectif principal ici est de concevoir un système pouvant répondre à ces exigences et nous permettant d'obtenir un comportement Plug and Play; cette approche est basée sur la "philosophie System of Systems ". utilisant des méthodologies de contrôle distribué.Cette thèse constitue une contribution au contrôle DC MicroGrid et introduit une analyse rigoureuse de la dynamique du system. La stabilisation du système repose sur des dispositifs de stockage: les batteries pour l'équilibre énergétique et la réponse à long terme des variations des flux d'énergie tandis que les supercondensateurs traitent l'équilibre des puissances et des variations rapide du system.Nous présenterons d’abord l’analyse du MicroGrid DC dont le contrôle est conçu à partir des modèles détaillés des sources d’énergie et des systèmes de stockage. Ce réseau peut présenter un comportement instable créé par intermittence de la source, les commutation des convertisseurs et leurs électroniques puissance et les courants oscillatoires produits par certains types de charges. Par conséquent, le système est sujet à des variations rapides et lentes. . La stabilisation de tels systèmes reposera sur le fonctionnement de différentes technologies de stockage, telles que la batterie et les supercondensateurs, qui opèrent dans différentes échelles de temps.Nous proposons un schéma de contrôle hiérarchique, basé sur la théorie du contrôle non linéaire, en particulier de Lyapunov, le backstraping et d’entrée / sortie de feedback linéarisation. Le DC MicroGrid proposé et son contrôle sont vérifiés à la fois par simulations et par expérimentation Les résultats montrent la bonne performance du système sous des variations de production et de consommation. / The large penetration intermittent energy sources, presents a new challenges to power systems' stability and reliability; we consider in this work their connection through a Direct Current (DC) MicroGrid and a hybrid storage system, in order to satisfy constraints of connection to the network (the so-called Grid-Codes). The main objective here is to design a system that can fulfil these requirements and allow us to attain a Plug and Play behaviour; this approach is based on the “System of Systems philosophy'' using distributed control methodologies.This thesis constitutes a contribution for DC MicroGrid control and introduces a rigorous dynamics' analysis.. The stabilization of the system is based on storage devices: batteries for energy balance and long term response of power flow, while supercapacitors deal with power balance and fast response.First it will be presented the analysis of the DC MicroGrid which control is designed based on detailed models of energy sources and storage systems. This grid may present an unstable behaviour created by the source’s intermittent output power, switching ripples from the power converters and their power electronic and oscillatory currents produced by some types of loads. Therefore the system is subject to both fast and slow variations. The stabilization of such systems will be based on the operation of different technologies of storage, such as battery and supercapacitor, in different time scales.We propose a hierarchical control scheme, based on nonlinear control theory, in particular Lyapunov, backstepping and input/output feedback linearization. The proposed DC MicroGrid and its control are then verified both by computer simulations and by experiments. The results show the good performance of the system under variations on production and on consumption