Design and characterisation of a novel translucent solar concentrator

This thesis begins with an investigation into the optical performances of the Crossed Compound Parabolic Concentrator (CCPC) for photovoltaic application and introduces the novel concept of a Translucent Integrated Concentrated Photovoltaic (TICPV). The use of solar concentrators in BIPV enables a reduction in the cost of generating photovoltaic electricity lending to yet another field of research known as Building Integrated Concentrated Photovoltaics (BICPV). The potential of BICPV as the most promising technologies for future electricity supply is examined by the design, optimisation and testing of the main component of the TICPV, a novel static nonimaging transparent 3-D concentrator coined the Square Elliptical Hyperboloid (SEH), for the use in building fenestrations. The SEH concentrator was designed and optimised via ray-tracing technique. A preliminary investigation into the optical efficiencies of 160 SEH concentrators of varying geometries was conducted and from this 20 concentrators were chosen and studied in more detail using the developed optical model with the aim of obtaining an optimised SEH concentrator out of these 20. The optimisation process proved to be far from straightforward, however, after careful consideration, five SEH concentrators with the best optical performances, each with different heights, were chosen. These concentrators were fabricated and used to assemble five separate TICPV modules. Subsequent to carrying out the simulation, the five optimised TICPV modules were examined in different environments (indoor and outdoor). The results of the indoor test, where the TICPV modules are exposed to direct radiation from a solar simulator, provided clear validation of the optical model; the results of the outdoor test added further to the validation and confirmed the power output of the TICPV modules when exposed to both direct and diffuse radiations. The TICPV modules are developed in a way such that they collect sunlight during most of the hours throughout the day, allowing the generation of electrical power whilst maintaining the level of transparency of the fenestration. It was found that the TICPV modules are capable of saving more than 60% of the solar cells used in conventional flat PV systems. The designed TICPV modules simultaneously provide solar energy generation and optimised day lighting. The TICPV module designed in this thesis provides a viable solution to coping with the increasing energy demands and will create a new age of energy efficient buildings reducing the carbon footprint of both existing buildings and buildings of the future

Dynamics of rising CO\u3csub\u3e2\u3c/sub\u3e bubble plumes in the QICS field experiment: Part 1 - The experiment

© 2015 The Authors. Published by Elsevier Ltd. The dynamic characteristics of CO2 bubbles in Scottish seawater are investigated through observational data obtained from the QICS project. Images of the leaked CO2 bubble plume rising in the seawater were captured. This observation made it possible to discuss the dynamics of the CO2 bubbles in plumes leaked in seawater from the sediments. Utilising ImageJ, an image processing program, the underwater recorded videos were analysed to measure the size and velocity of the CO2 bubbles individually. It was found that most of the bubbles deform to non-spherical bubbles and the measured equivalent diameters of the CO2 bubbles observed near the sea bed are to be between 2 and 12 mm. The data processed from the videos showed that the velocities of 75% of the leaked CO2 bubbles in the plume are in the interval 25-40 cm/s with Reynolds numbers (Re) 500-3500, which are relatively higher than those of an individual bubble in quiescent water. The drag coefficient C d is compared with numerous laboratory investigations, where agreement was found between the laboratory and the QICS experimental results with variations mainly due to the plume induced vertical velocity component of the seawater current and the interactions between the CO2 bubbles (breakup and coalescence). The breakup of the CO2 bubbles has been characterised and defined by Eötvös number, Eo, and Re

A comprehensive review on the potential of green hydrogen in empowering the low-carbon economy: development status, ongoing trends and key challenges.

Green hydrogen is currently considered a key element for delivering free-carbon energy. This paper provides an extensive assessment of the potential of green hydrogen technology as a pathway to the low-carbon economy while highlighting the major technical challenges to its implementation. A detailed overview of green hydrogen production, storage technologies, transportation infrastructures and green hydrogen implementations is provided. Status of the ongoing trends for repurposing the existing gas grid infrastructures to transport the hydrogen safely across Europe is presented in this work, with 48 sample projects statistically reviewed and classified based on the key challenges being addressed. The potential of green hydrogen in decarbonizing the energy sector and the associated technical challenges are widely reviewed and critically assessed. Detailed discussions have been provided on the optimal sizing of renewable hydrogen energy systems, real-world modelling of hydrogen energy storage elements and the smart energy management strategies for the application of hydrogen electrolysers as smart controllable loads. Some prospects are given on how digital key trends of blockchain technologies could support the growth of green hydrogen markets together with emphasis on the raised research questions. Further assessment is presented on the potential of green hydrogen versus blue hydrogen while reflecting on future directions and policy recommendations for planning a successful energy transition. Finally, some future insights and near-term policy recommendations are provided for promoting the use of green hydrogen production while supporting the green hydrogen industry

Dynamics of rising CO2 bubble plumes in the QICS field experiment: Part 2 – Modelling

An oceanic two-phase plume model is developed to include bubble size distribution and bubble interactions, applied to the prediction of CO2 bubble plume and CO2 solution dynamics observed from the recent QICS field experiment in the Scottish sea at Ardmucknish Bay. Observations show bubbles form at between 2 and 12 mm in diameter, where the inclusion of the interactions within the simulations brings results of bubble plumes closer to that of the experiment. Under a given leakage flux, simulations show that the bubble size affects the maximum pCO2 dissolved in the water column, while the bubble interactions affect the vertical bubble distribution. The maximum modelled pCO2 increases from a background 360 μatm to 400, 427 and 443 μatm as CO2 injection rates increase from 80, 170 to 208 kg/day respectively at low tide. An increase of the leakage rate to 100% of the injection rate shows the maximum pCO2 could be 713 μatm, approaching the mean pCO2 observed of 740 μatm during the high leakage component of the experiment, suggesting that the flux may be greater than estimated due to the varied flux and activity across the pockmarks during the leakages

Modeling and simulation of heterojunction solar cell; determination of optimal values.

A heterojunction solar cell of ZnSe/ZnO/CIGS/Si structure has been simulated in order to determine the optimal values. The performed modeling and Simulation is used to get an idea and identify the optimal values that can be use in the manufacturing process, and the values obtained in this simulation presented an electrical parameters using Solar Cell Capacitance Simulator (SCAPS). In this study, the influence of absorber or wafer thickness and doping concentration were varied on the solar cell device and the following optimal values were obtained; Current density (Jsc)=35.0833SmA/cm2, Open circuit voltage (Voc)=0.S339V, Fill Factor (FF) =S5.45%, and an efficiency (η)=25%. The range of doping concentration (lx1012 to lx1020 cm−3). These variations lead to the achievement of 25% efficiency of the heterojunction solar cell and the optimal values shows a promising performance that the manufacturers can adopt

Building Integrated Photovoltaics—The Journey So Far and Future

The road to decarbonization has led to the exploration of sustainable energy sources for domestic and industrial use. Various nations have shown commitment and, hence, set ambitious targets, with the overall aim of cutting down greenhouse gas (GHG) emissions across the board. The fight against climate change seems to be intensifying, partly due to the visible signs of environmental hazards and threats to human life and the ecosystem. Environmental policies, behavioural changes and complex decisions have been taken in various sectors to ensure set targets are met

State-of-the-Art Review on the Energy Performance of Semi-Transparent Building Integrated Photovoltaic across a Range of Different Climatic and Environmental Conditions

Semi-transparent Building Integrated Photovoltaics provide a fresh approach to the renewable energy sector, combining the potential of energy generation with aesthetically pleasing, multi-functional building components. Employing a range of technologies, they can be integrated into the envelope of the building in different ways, for instance, as a key element of the roofing or façade in urban areas. Energy performance, measured by their ability to produce electrical power, at the same time as delivering thermal and optical efficiencies, is not only impacted by the system properties, but also by a variety of climatic and environmental factors. The analytical framework laid out in this paper can be employed to critically analyse the most efficient solution for a specific location; however, it is not always possible to mitigate energy losses, using commercially available materials. For this reason, a brief overview of new concept devices is provided, outlining the way in which they mitigate energy losses and providing innovative solutions for a sustainable energy future

Promoting the Solar Industry in Ghana through Effective Public-Private Partnership (PPP): Some Lessons from South Africa and Morocco

Over the past decades, solar energy has gained much attention in Ghana, especially after the 2012–2016 power crisis. The government through Public-Private Partnerships (PPPs) has attempted to increase the shares of solar generation to augment its efforts in reducing the energy deficit of the country, especially in remote and off-grid communities. However, the extent to which PPP has been utilized as a viable tool for solar sector development in Ghana is questionable. This study discusses the current state of PPPs in Ghana’s solar industry and compares how it has been efficiently used as a tool to promote the solar industry in South Africa and Morocco. Fundamental theories such as Altruism, Game, Principal-agent, and Pareto Optimality (PO) were used as analytical tools to examine how PPPs are handled in the selected cases. The study ascertains that the Game and PO are applicable theories that have guided SA and Morocco’s solar infrastructural development. This study discovered that PPP has been efficiently used in SA and Morocco to push its solar industry to be among the best in the world and Ghana can perfectly emulate it. The study further reveals that the Principal-agent analogy and altruistic intent of the Ghanaian government tend to discourage Private sector participation in the solar industry. It further suggests the Pareto Optimality, Game approach, and a win-win transparent attitude towards PPPs. This study recommends a well-developed PPP structure and law for Ghana. It encourages transparency and discourages partisan preferentialism to increase PPPs in Ghana’s solar industry

Performance Improvement of a CPV System: Experimental Investigation into Passive Cooling with Phase Change Materials

High temperature and overheating of photovoltaic panels lead to efficiency losses and eventual degradation. For solar PV systems, this is a significant impediment for achieving economic viability. In this study, a novel Window-Integrated Concentrated Photovoltaic (WICPV) system is proposed for window integration. This offers high (50%) transparency and is fabricated and characterised indoors at an irradiance of 1000 Wm−2. Its electrical performance is tested (a) without applied cooling (i.e., under natural ventilation) and (b) with a heat sink to accommodate passive cooling media. The results are compared to study the effects of reduction in operating temperature on system performances. The effectiveness of a sensible cooling medium (water) and two latent heat removal media, phase change materials (or PCMs, RT50 and RT28HC), is investigated. This paper reports the passive temperature regulation of this WICPV at ambient testing conditions. The results demonstrate an increase in electrical power output by (i) 17% (RT28HC), (ii) 19% (RT50), and (iii) 25 % (circulating water) compared with the naturally ventilated system. This shows that PCMs are considerably useful for thermal regulation of the WICPV. Any improvement in efficiencies will be beneficial for increasing electrical energy generation and reducing peak energy demands