In the quest to reduce the release of carbon dioxide to limit the effects of global climate change, tidal-in-stream energy is being investigated as one of many possible sustainable means of generating electricity. In this scheme, turbines are placed in a tidal flow and kinetic energy is extracted. With the goal of producing maximum power, there is an ideal amount of resistance these turbines should provide; too little resistance will not a develop a sufficient pressure differential, while too much resistance will choke the flow. Tidal flow in a strait is driven by the difference in sea-level along the channel and is impeded by friction; the interplay between the driving and resistive forces determines the flow rate and thus the extractible power. The use of kinetic energy flux, previously employed as a metric for extractible power, is found to be unreliable as it does not account for the increased resistance the turbines provide in retarding the flow. The limits on extraction from a channel are dependant on the relationship between head loss and velocity. If head loss increases with the square of the velocity, a maximum of 38% of the total fluid power may be extracted; this maximum decreases to 25\% if head loss increases linearly with velocity. Using these values, the estimated power potential of BC's Inside Passage is 477MW, 13% of previous assessments. If a flow has the ability to divert through a parallel channel around the installed turbines, there are further limits on production. The magnitude of this diversion is a function of the relative resistance of impeded and diversion channels. As power extraction increases, the flow will slow from its natural rate. This reduction in velocity precipitously decreases the power density the flow, requiring additional turbine area per unit of power. As such, the infrastructure costs per watt may rise five to eight times as additional turbines are installed. This places significant economic limitations on utility-scale tidal energy production. / Applied Science, Faculty of / Civil Engineering, Department of / Graduate

The increasing demand for electricity, the rising price of energy from conventional sources and limited electricity supply are a global concern. The demand on electricity generation could be alleviated by diversifying the sources from which electricity is obtained to achieve the goals of long-term electricity supply. Diversification implies finding alternative sources of energy such as renewable energy for the production of electricity. The South African electricity system is under increased pressure to provide and maintain electricity supply to its users. Electricity production may be regarded as a key contributor to the social and economic development of South Africa. The challenges are so serious that it will gradually become increasingly difficult to extract sufficient resources to satisfy increasing electricity demand. Growth in the electricity and industrial sectors signifies profound changes in the entire energy industry. The South African power utility Eskom, supplies 94% of South Africa’s electricity but the risk of inadequate supply because of increasing electricity demand is mitigated through the employment of Independent Power Producers (IPPs) which supply to the grid. However, although a limited number of IPP entrepreneurs sell electricity to the Eskom grid, there is no enabling entrepreneurial environment in which they can thrive. There is no positive movement to inaugurate policies and processes. This has created an opportunity for Smart Grid access as a viable option to accommodate IPP entrepreneurs into the grid. Investing in renewable electricity sources may provide feasible alternatives for the electricity industry, it would alleviate pressure on current supply whilst creating an enabling entrepreneurial environment for IPP entrepreneurs and increase entrepreneurial activity. This study investigates a proposed model for an enabling entrepreneurial environment for IPPs in the RE sector that can be utilised to ensure increased entrepreneurial activity within the electricity industry. Establishing such an enabling environment would contribute positively to the alleviation of the electricity demand crisis, result in lower carbon emissions and create a sustainable, more diverse electricity generation mix. This proposed IPP industry model for an enabling entrepreneurial environment is presented to address the problems experienced at the different levels of the electricity industry. The model can be utilised to increase entrepreneurial activity while eradicating major electricity challenges at different levels in the South African electricity industry. The results indicate that that RE, in the form of solar and wind, has the potential to expand the South African electricity industry significantly. Therefore, in order to reform the South African electricity industry, stakeholders need to embrace entrepreneurship as IPP entrepreneurs. This can be done effectively by the incorporation of IPP entrepreneurs into the electricity network. However, an enabling entrepreneurial environment in which to operate must be ensured. In this study, five important variables support the establishment of an enabling entrepreneurial environment for IPP entrepreneurs. These have been identified as; Smart Grids, Entrepreneurship, Renewable electricity environment, SA policy and Stakeholder theory. An important contribution has been made towards Stakeholder Theory. This has proven to be instrumental within the RE sector of the electricity industry in South Africa, as the mentioned role players have a reciprocal role to play. Three surveys were conducted at three levels of the electricity industry, namely, at organisational, legislative and entrepreneurial levels and included Eskom Management, National Energy Regulator (NERSA) Management and Approved and Non-approved IPPs. Both qualitative and quantitative research methods were utilised in this research study. The results indicate that SA Policy is instrumental in assisting stakeholders to facilitate the IPP process and feed the power from RE generation into the network. Most respondents were positive about the role of Smart Grids in future electricity generation and their contribution towards creating an enabling entrepreneurial environment for IPP entrepreneurs. Respondents indicated that by policy decisions, greater emphasis can be placed on the results of climate change and environmental challenges. Emphasis on the incorporation of stakeholders proved imperative to this group (IPPs). The results indicated that stakeholder management is a key factor contributing to the establishment of an enabling entrepreneurial environment. The major contribution of this study is a proposed entrepreneurial model that can improve future sustainability of the electricity supply.

The study found that investing in solar water heater system (SWH) would be an economically, socially and environmentally viable option to implement within urban households; in which the hot water demand, volume of hot water consumption, water heating costs, and electricity tariffs are high. Investing in solar water heater technology should be the key focus of South African government; in order to enhance the wellbeing of the ordinary citizens. The study made use of the qualitative research approach to investigate solar water heater drivers and barriers; from the perspective of energy consumers. This will be achieved by focusing on the major drivers and barriers that consumers consider when making decisions on adoption of solar water heater system. It is believed that solar water heater drivers and barriers substantially influence the potential and urban development thereof. Solar heat is utilized in the residential sector for heating water for bathing, cleaning, washing and cooking food, but its availability is limited (Arora & Arora, 2013). Renewable energy has become a wild card internationally and regionally because of the technical, economic and environmental barriers affecting the disadvantaged individuals.

The research described in this dissertation was motivated by the global demand for energy that is not dependent on coal, oil, natural gas and other non-renewable fossil fuels. The technology used in this project is related to the use of biomass to produce a viable alternative to conventional sources of fuel. A bench scale biomass to liquid (BTL) facility was built and tested. This produced results confirming the feasibility of the BTL process. The findings of the pilot study outlined in this dissertation justified the conclusion that the next step will be to expand the capacity and productivity of the BTL pilot plant to an industrial scale. Biomass comes from a variety of renewable sources that are readily available. In this case, the material used in the fixed bed biomass gasification facility to generate wood gas was agricultural and forestry waste, such as straw and wood chips. The gasifier had the capacity to produce up to 10 cubic metres/hr of gas with a carbon monoxide and hydrogen content of between 20–40% by volume, when it was operated at ambient pressure and with air as the oxidizer. The gas, produced at a temperature above 700º C, was cooled in a quench/water scrubber in order to remove most of the mechanical impurities (tars and water-soluble inorganic particles), condensed and dried with corn cobs before being compressed in cylinders at over 100 bar (g) for use in the Fischer-Tropsch Synthesis (FTS). The syngas was subjected further to a series of refining processes which included removal of sulphur and oxygen. The sulphur removal technology chosen entailed applying modified activated carbon to adsorb H2S with the help of hydrolysis in order to convert organic sulphur impurities into H2S which reduced the sulphur content of the gas to less than 5 ppbv. Supported cobalt catalyst (100 grams), were loaded into a single-tube fixed bed FT reactor with an inner diameter of 50 mm. The reactor was fitted with a heating jacket through which, heated oil ran to cool the reactor during a normal reaction occurring at < 250 ºC, while nitrogen was used in the heating jacket during reduction, which occurred at temperatures up ~ 350 ºC. The FTS reaction was carried out at different pressures and temperatures. Liquid and wax products were produced from the facility. The properties of the liquid and solid hydrocarbons produced were found to be the same as FT products from other feed stocks, such as natural gas and coal.

Climate Change and Energy Security have been dominating the global energy agenda. In response the United Kingdom (UK) set a target of reducing emissions by 80% by 2050, and have accepted the European Directive to produce 15% of energy by renewable resources by 2020. Despite doubts in the last few years, the UK are on track to not only meet but exceed the target placed upon them, which sets them in good light for the long term 2050 emission reduction. This research investigated the barriers in the industry such as the planning process delays and public perception. Findings suggested that negative public perceptions still remain, with onshore projects gaining more attention than offshore projects. The planning system whilst showing an improvement in overall decision time still showed signs of delays in the pre-examination process. The research also highlighted signs of a predicted development plateau in onshore schemes, with approved capacity rates slowing in the year 2014. Furthermore, the political structure surrounding wind energy has become fragile, following recent comments from the Conservative party, suggesting they will see an end to onshore wind should they gain election in 2015. Therefore despite positive steps taken by the UK towards renewable energy targets, the future of wind energy is not certain.

Le but de cette thèse est l'optimisation de la production de l'électricité renouvelable pour site isolé de faible puissance. Un système, utilisant deux sources renouvelables : photovoltaïque et éolienne, est étudié afin d'améliorer le rendement énergétique de l'énergie produite. Pour la chaîne de conversion photovoltaïque, un contrôleur pour suivre le point de puissance maximale est conçu en utilisant l'approche de recherche directe (méthode Perturbe & Observe) combinée avec la logique floue, tout en prenant en compte le sens de variation des perturbations. Avec cette combinaison, on peut éviter des défauts de la méthode Perturbe & Observe, s'affranchir des informations sur les caractéristiques du panneau photovoltaïque et des conditions climatiques. Egalement, pour la chaîne de conversion éolienne de petite puissance fonctionnant à vitesse variable couplée à un générateur synchrone à aimant permanent, un contrôleur pour suivre le point de puissance maximale est proposé qui est basé sur le même principe par rapport à la chaîne de conversion photovoltaïque. Cette approche proposée a l'avantage de l'utilisation d'un capteur de tension au lieu d'un capteur de vitesse, ceci présente un intérêt certain notamment pour sites isolés par rapport aux autres solutions. Enfin, pour la réalisation d'un système de production d'électricité hybride, un superviseur est conçu pour obtenir un comportement optimal du système en fonction des variations de la charge et de la production en prenant en compte du système de stockage et de délestage. Pour chaque point abordé, des études en simulation sont fournies pour montrer l'efficacité des approches proposées. / The objective of this thesis is to optimize the production of renewable electricity for small isolated network. A system using two renewable sources: solar and wind power, is studied in order to improve the efficiency of energy extracted. For the photovoltaic conversion system, a maximum power point tracking controller is designed using direct searching approach (method Perturbe & Observe) combined with fuzzy logic, taking into account the direction of perturbation. This combination can avoid the disadvantages of the method Perturbe & Observe, and not requires any information about the generator's characteristics or climate conditions. Similarly, for the variable speed wind turbine using permanent magnet synchronous generator, a controller to track the maximum power point, based on the same principle with photovoltaic conversion system, is proposed. This approach has the advantage of using a voltage sensor instead of a speed sensor, this presents a particular interest for stand-alone system comparing to other solutions. Finally, for the realization of hybrid generation system, a fuzzy supervisor is adapted to obtain an optimal behavior of the system according to the variations of load demand and extracted power, taking into account the storage and dissipation system. For each issue, simulation studies are provided to show the effectiveness of the proposed approaches.

Given increasing problems in the availability, affordability and deliverability of commercial primary and secondary energy resources, coupled with growing macroeconomic uncertainties, the use of renewable, non-commercial energy resources has been actively promoted in rural areas of developing countries. This, in addition to the fact that conventional, 'state-of-the-art' energy facilities present technical problems, are inequitable and pose potential environmental hazards, has led to proposals for instituting alternative, intermediate or 'appropriate' technologies in rural settlements. This thesis identifies technical, economic, social, cultural and institutional barriers to the introduction of intermediate or 'appropriate' technologies in rural areas. The cases of solar and biogas technologies in Korea, Malaysia, Papua New Guinea the Philippines and Thailand are considered. Policy and planning process recommendations are made on the roles of government, voluntary aid-agencies and the rural user, to overcome the obstacles to implementing these technologies. These recommendations cover the micro (village) and macro (regional and national) levels over two time horizons, and stress the need for a comprehensive approach to discerning rural needs, followed by integrated technology diffusion through effective program and project implementation. In addition, this thesis identifies the need for a continuous collection of information on rural socio-economic conditions and potential for rural interfuel substitution and finally, recommends research into improving technical efficiencies of alternative energy technologies such as solar and biogas. Alternative or intermediate energy technologies such as solar and biogas can play an important role in augmenting rural energy supply. Unless steps are taken to remove the identified barriers to implementation in future technology diffusion efforts, this potential will not be realized. Policy and planning process recommendations made in this thesis present means through which these barriers could be removed. / Applied Science, Faculty of / Community and Regional Planning (SCARP), School of / Graduate

M.Phil. ( Energy Studies) / In contrast to conventional energy sources, the advantage of renewable energy lies in the fact that it is virtually inexhaustible and that its utilisation is accompanied by minima environmental pollution. I t is, furthermore, very appropriate especially seen in the light of the large Third World component of the South African energy economy. It therefore becomes necessary to evaluate the adequacy of Government strategy as far as the optimal development and utilisation of the renewable energy sources with the best potential in South Africa are concerned, against present and future needs for and the utilisation possibilities of these sources...

abstract: The operating temperature of photovoltaic (PV) modules has a strong impact on the expected performance of said modules in photovoltaic arrays. As the install capacity of PV arrays grows throughout the world, improved accuracy in modeling of the expected module temperature, particularly at finer time scales, requires improvements in the existing photovoltaic temperature models. This thesis work details the investigation, motivation, development, validation, and implementation of a transient photovoltaic module temperature model based on a weighted moving-average of steady-state temperature predictions. This thesis work first details the literature review of steady-state and transient models that are commonly used by PV investigators in performance modeling. Attempts to develop models capable of accounting for the inherent transient thermal behavior of PV modules are shown to improve on the accuracy of the steady-state models while also significantly increasing the computational complexity and the number of input parameters needed to perform the model calculations. The transient thermal model development presented in this thesis begins with an investigation of module thermal behavior performed through finite-element analysis (FEA) in a computer-aided design (CAD) software package. This FEA was used to discover trends in transient thermal behavior for a representative PV module in a timely manner. The FEA simulations were based on heat transfer principles and were validated against steady-state temperature model predictions. The dynamic thermal behavior of PV modules was determined to be exponential, with the shape of the exponential being dependent on the wind speed and mass per unit area of the module. The results and subsequent discussion provided in this thesis link the thermal behavior observed in the FEA simulations to existing steady-state temperature models in order to create an exponential weighting function. This function can perform a weighted average of steady-state temperature predictions within 20 minutes of the time in question to generate a module temperature prediction that accounts for the inherent thermal mass of the module while requiring only simple input parameters. Validation of the modeling method presented here shows performance modeling accuracy improvement of 0.58%, or 1.45°C, over performance models relying on steady-state models at narrow data intervals. / Dissertation/Thesis / Masters Thesis Engineering 2020

Wind power generation has gained a large share in the renewable energy market over the past few years. This study investigates the impact of large scale penetration of permanent magnet synchronous generator (PMSG) based wind turbines on power quality of the grid. PMSGs are attractive due to the absence of a gearbox in the drive-train, which results in lower maintenance costs and higher reliability. Moreover, the advancements in power electronics have facilitated PMSGs to generate optimal power at varying wind speed conditions. This is achieved through the use of maximum power point tracking algorithms. The drawbacks of PMSG-based wind energy systems are that they inject harmonics into the network and cause flicker as well as other power quality issues. Despite these disadvantages, the grid code requires that PMSGs stay connected to the grid even under grid disturbances. This is because the reactive power control capability of PMSG-based wind energy systems can actually assist with voltage support. It will be shown in this study that disconnecting large scale PMSGs based wind turbines during grid disturbances has a detrimental effect on transient stability of the grid. This study will show that PMSG-based wind energy systems improve transient stability and assist in voltage support through reactive power control. Moreover, the impacts of large scale PMSG based wind turbines on power quality of the grid can be reduced by various means, which are also addressed in the study.