Search results for "Solar"

Properties of SnO2:F/p-type aSi:H interface in thin film a-Si:H solar cells

2011

Carbon Nitride-Based Catalysts for High Pressure CO2 Photoreduction

2022

In the current research, the productivity of CO2 photoreduction has been boosted by performing the reaction in an innovative photocatalytic reactor, which allows for operation up to 20 bar. A set of photocatalysts were used, including three types of pristine TiO2, i.e., one commercially prepared (Evonik P25), one home-prepared by flame spray pyrolysis (FSP), and one obtained by the hydrolysis of TiCl4 (TiO2exCl), a bare thermo-exfoliated carbon nitride (C3N4-TE), and binary materials composed of TiO2 and C3N4-TE. The photoreduction was carried out in water at pH 14 and in the presence of Na2SO3 as a hole scavenger. Hydrogen and very small amounts of CO were detected in the head space of the…

Three-dimensional core-collapse supernovae with complex magnetic structures: I. Explosion dynamics

2021

Magnetic fields can play a major role in the dynamics of outstanding explosions associated to violent events such as GRBs and hypernovae, since they provide a natural mechanism to harness the rotational energy of the central proto-neutron star and power relativistic jets through the stellar progenitor. As the structure of such fields is quite uncertain, most numerical models of MHD-driven core-collapse supernovae consider an aligned dipole as initial magnetic field, while the field's morphology can actually be much more complex. We present three-dimensional simulations of core-collapse supernovae with more realistic magnetic structures, such as quadrupolar fields and, for the first time, an…

TRANSITION METAL OXIDES AS SELECTIVE CONTACTS FOR C-SI SOLAR CELLS

2021

Estudio de pequeños elementos magnéticos en la fotosfera y cromosfera solar con telescopios en tierra y espaciales = Study of small magnetic elements…

2011

The photosphere is the best known layer of the Sun, as it delimits its surface and furthermore, it has been observed in detail since the beginning of the telescopic era. The convection zone redistributes the magnetic field over the photosphere and the upper layers. On the many scales of the solar surface magnetism, the smallest elements seen in the photosphere are the most unknown, due to the limit in resolution of a finite telescope. The structures that are smaller than typically 100 km are smeared out. In this Thesis, the small bright features of the magnetic network and internetwork over the resolution limit are analysed from the dynamical point of view, and linked with their physical pr…

Stationary, Second Use Battery Energy Storage Systems and Their Applications: A Research Review

2021

The global demand for electricity is rising due to the increased electrification of multiple sectors of economic activity and an increased focus on sustainable consumption. Simultaneously, the share of cleaner electricity generated by transient, renewable sources such as wind and solar energy is increasing. This has made additional buffer capacities for electrical grids necessary. Battery energy storage systems have been investigated as storage solutions due to their responsiveness, efficiency, and scalability. Storage systems based on the second use of discarded electric vehicle batteries have been identified as cost-efficient and sustainable alternatives to first use battery storage syste…

Discovery of an Exceptionally Strong β -Decay Transition of $^{20}$F and Implications for the Fate of Intermediate-Mass Stars

2019

A significant fraction of stars between 7-11 solar masses are thought to become supernovae, but the explosion mechanism is unclear. The answer depends critically on the rate of electron capture on $^{20}$Ne in the degenerate oxygen-neon stellar core. However, due to the unknown strength of the transition between the ground states of $^{20}$Ne and $^{20}$F, it has not previously been possible to fully constrain the rate. By measuring the transition, we have established that its strength is exceptionally large and enhances the capture rate by several orders of magnitude. This has a decisive impact on the evolution of the core, increasing the likelihood that the star is (partially) disrupted b…

An Economic Assessment of Micro-Scale Use of Renewable Energy Sources: Two Case Studies

2015

During recent times, renewable energy technologies have shown a relative fast growth in the global energy investment, global energy capacity and their integration within multiple sectors, particularly in the electricity sector. Renewable energy technologies have also experienced notorious declining costs on their manufacturing production. Nevertheless, while this growth is widely acknowledged, the share of renewables with respect total energy production has been moderate. Technological advancements in renewable energy have demonstrated the potential of renewables in energy generation and also that renewables can provide direct and indirect advantages over their counterparts. This thesis inv…

Impact assessment of a solar powered water treatment project

2015

Water treatment technologies are seen as the best alternative to be considered for adoption in developing countries where access to portable water supply that is free of pathogens is yet a challenge. This study intended to assess impact brought forth by a project, which employed a water treatment technology in rural settings of Morogoro Region in Tanzania. The project used solar photovoltaic panels to trap solar energy, converted to mechanical power to treat water with the help of sterilization ultraviolet membrane. A comparative analysis was used as an assessment framework to study impacts of the project with respect to the quality of approach used during the project life cycle. Determinan…

Vertically Aligned Nanowires and Quantum Dots: Promises and Results in Light Energy Harvesting

2023

The synthesis of crystals with a high surface-to-volume ratio is essential for innovative, high-performance electronic devices and sensors. The easiest way to achieve this in integrated devices with electronic circuits is through the synthesis of high-aspect-ratio nanowires aligned vertically to the substrate surface. Such surface structuring is widely employed for the fabrication of photoanodes for solar cells, either combined with semiconducting quantum dots or metal halide perovskites. In this review, we focus on wet chemistry recipes for the growth of vertically aligned nanowires and technologies for their surface functionalization with quantum dots, highlighting the procedures that yie…