Globally and in most emerging economies such as South Africa, there is an urgent need to attain sustainable development goals as well as honor climate change mitigation commitments. In order to achieve this and to participate in a global transition to clean, low-carbon energy systems, it is imperative for South Africa to focus on its energy transition strategy. In South Africa, the current energy system is mainly reliant on fossil fuel, nuclear and gas energy sources. The high reliance on fossil fuels combined with an old fleet of power plants have intensified the challenges of unsustainability, poor security of supply, as well as unreliability demonstrated in frequent disruptions in the electricity supply. The South African energy supply system is in great need for transformation through the strengthening of cleaner and sustainable energy technologies. This thesis used the international energy supply mix comparison, energy supply mix drivers causality analysis, as well as the energy supply mix system modelling to investigate and propose an optimal energy supply mix which is aligned to the current South African national policy frameworks as well as the strategic targets and plans which enable a sustainable and secure energy transition. The overarching aim of this study was to investigate the role of renewable energy in the South African energy supply mix and economy. To do so, the specific research questions of the study were: 1) How is South Africa’s planned energy supply mix relative to the rest of the world and how has it changed in recent years? ; 2) What is the relationship between renewable energy and economic growth in South Africa?; 3) What is the optimal energy supply mix that is used in South Africa in order to assist with the transition from fossil fuels to renewable energies? These questions were addressed through three research papers around which the thesis is structured. The study’s findings advance the EnergyPlan system modelling tool and methodology and its introduction in the South African context. In terms of its energy supply mix (specifically electricity supply mix), South Africa is still heavily dependent on fossil fuels and there is a need for diversification towards a cleaner and sustainable energy supply mix. As a result, it is evident that nonrenewable energy has the most impact on economic growth. There is also a need to increase R&D expenditure and energy technology development. The key contribution of this thesis is the introduction to the South African context an energy supply mix methodology and tool that can be used to accurately determine the maximum contribution of renewable energy into the South African energy supply mix at the least cost and minimum emissions enabling the transition from a fossil fuel dominated mix to one that has more renewable energy. Also providing an evaluation of the role of renewable energies in the future optimal energy supply mix of the country and empirically evaluating and discussing the current Intergrated Resource Plan (IRP) as part of the process. In this regard, identifying the gaps in the current energy mix against likely scenarios based on the current economic climate. As well as better informing the policy makers and key stakeholders in the electricity industry on the role and effect of preferring a renewable -based energy supply mix. / Thesis (PhD)--University of Pretoria, 2020. / Eskom; University of Pretoria / Economics / PhD / Unrestricted

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A research report submitted to the Faculty of Engineering and Built Environment, University of the Witwatersrand, in partial fulfilment of the requirements for the degree of Masters of Architecture in the field of Sustainable and Energy Efficient Cities Johannesburg May 2018 / Based on the Sol Plaatje Municipality case study, this study focuses on how an innovative municipal business and funding approach could serve as a tool for transitioning from fossil fuels to renewable energy (solar) for the benefit of both indigent households and the municipality. Primary data from the municipality and indigent households in Galeshewe settlement indicates that in its current form, the 50kWh free basic electricity that indigent households receive monthly from the municipality is insufficient for their basic energy needs, while purchasing additional electricity is becoming increasingly unaffordable. This results in suppressed demand for the households and ongoing risk to the municipality due to escalating costs. In mitigation of the two fundamental challenges, findings from primary and secondary data have guided the study to the Renewable Energy for Low Income Earners (RELIE) model. The Equitable Share Grant and Integrated National Electrification Programme Grant (as currently allocated to municipalities by National Treasury and the Department of Energy for free basic electricity and electricity infrastructure provision for low income households) are highlighted as the initial funding channels under the proposed model based on a backcasting approach. Municipal energy plans and policies as well as integrated human settlements’ spatial plans also emerge as critical tools for transitioning to inclusionary RE. Other funding sources in the RELIE model include existing government funds such as the Green Fund and the Central Energy Fund from the Department of Environmental Affairs, as well as supplementary funds from relevant agencies such as climate funding entities and philanthropic socially responsive investments. The model also envisages end-user contribution through affordable payments for service. In conclusion, the study recommends that the RELIE model findings could be adapted for other municipalities in South Africa faced with the escalating indigent household energy crisis. / MT 2018

Worldwide energy consumption is estimated to double between 2008 and 2035. Over-dependence on energy imports from a few, often politically unstable countries, and unpredictable oil and gas prices, pushes energy to a critical agenda. While there is an agreement that we need to change the production and consumption of energy, there is still disagreement about the specific changes that are needed and how they can be achieved. The conventional energy plans relying primarily on fossil fuels and nuclear technologies, which are in need of transformation due to limited resources and carbon dioxide emissions. Energy efficiency improvements and renewable energy should play a leading role in the America's energy future. Energy and environmental organizations believe that renewable energy and energy efficiency can meet half of the world's energy needs by 2050. This thesis describes a model that predicts renewable energy portfolios for the Southern portion of the United States, by evaluating multiple renewable energy sources such as solar, wind, hydropower, biomass, and geothermal. The Southern US is divided into three regions: Southwest, South Central, and Southeast, which are chosen given their location and the level of abundance of renewable resources, thereby minimizing inefficiencies and losses associated to the present generation system. A mathematical predictor takes into account variables such as supply/demand, non-renewable/renewable sources, and time. From the results, the Southwest and South Central regions confirm an surplus of renewable electricity by 2050, but the Southeast region does not have enough renewable resources to detach itself from the use of fossil fuels. The South Central region begins producing a surplus of renewable energy in 2014 and reaches an excess amount of 14,552 billion KWh by 2050. This means there will be no need to transfer electricity over long distances, which will increase the overall efficiency of electrical generation.

Published Article / The world is increasingly being misused by its inhabitants by the wasteful manner that its resources are utilized and the amount of pollution that is generated in the environment. This practice is unsustainable and it is incumbent on the present generation of decision-makers to rectify this phenomenon if our descendants are to have an opportunity to live life in the same manner as we do. Special emphasis should be placed on a reduction in the amount of air pollution that is created by electrical power generating plants, as well as the manner in which potable water is utilized and wasted. In this article the local situation with respect to the generation and use of electrical energy and water is discussed. It is encouraging to see that the National Government is taking strong steps to address these problems. Yet, it might not have the required ability to finance these efforts fully.

Marine currents, i.e. water currents in oceans and rivers, constitute a large renewable energy resource. This thesis presents research done on the subject of marine current energy conversion in a broad sense. A review of the tidal energy resource in Norway is presented, with the conclusion that tidal currents ought to be an interesting option for Norway in terms of renewable energy. The design of marine current energy conversion devices is studied. It is argued that turbine and generator cannot be seen as separate entities but must be designed and optimised as a unit for a given conversion site. The influence of support structure for the turbine blades on the efficiency of the turbine is studied, leading to the conclusion that it may be better to optimise a turbine for a lower flow speed than the maximum speed at the site. The construction and development of a marine current energy experimental station in the River Dalälven at Söderfors is reported. Measurements of the turbine's power coefficient indicate that it is possible to build efficient turbines for low flow speeds. Experiments at the site are used for investigations into different load control methods and for validation of a numerical model of the energy conversion system and the model's ability to predict system behaviour in response to step changes in operational tip speed ratio. A method for wake measurements is evaluated and found to be useful within certain limits. Simple models for turbine runaway behaviour are derived, of which one is shown by comparison with experimental results to predict the behaviour well.

The global energy system is dominated by the use of fossil fuels. This system suffers from several problems, such as different environmental issues, while the long-term energy security is sometimes questioned. As an alternative to this situation, a transition to a global energy system based on renewable energy technologies, to a large extent solar and wind energy, is commonly proposed. Constructing the technology needed for such a transition requires resources and how fast this could happen is somewhat disputed. This thesis explores methods to assess the potential constraints for realizing such a transition by looking at potential technology growth rates and outlooks of production of the required natural resources. The thesis is based on three papers presenting case studies that look at growth rates of wind energy as well as future production outlooks of lithium and phosphate rock. Using different types of growth patterns reaching proposed installed capacities of wind power, annual commissioning requirements are investigated, taking account for the limited life expectancy oftechnology. Potential outlooks of mineral production are explored using resource constrained curve-fitting models on global lithium production. A more disaggregated model looking at individual countries are used on phosphate rock production to investigate new perspectives on production outlooks. It is concluded that the growth rates of individual energy technologies affect the resource requirements and prospective constraints on energy transitions. Resource constrained modelling of resource production can provide spans of potential outlooks for future production of resources required for anenergy transition. A higher disaggregation of the modelling can provide new perspectives of potential constraints on future production. These aspects should be further investigated when proposing alternative future energy systems.

Human activities pressure the socio-ecological system that maintains our quality of life by causing global repercussions such as climate change. The energy system, a major contributor to climate change due to its reliance on fossil fuels makes the transition to sustainable energy an imperative. The purpose of this thesis is to identify focus areas that support businesses in changing their energy habits. This leads to the research question: How can local businesses on small islands become drivers in the transition towards sustainable energy? The Framework for Strategic Sustainable Development (FSSD) enabled us to employ a systems perspective, place sustainable energy into a comprehensive and scientific definition of sustainability, and align our findings’ relevance to a strategic approach. The Motivation-capability-implementation- results (MCIR) framework was a suitable tool for our needs. For data collection purposes, literature analysis and a case study on the French island Île d’Oléron were conducted. The main findings of the thesis are that in order for businesses to become drivers in the transition to sustainability energy, Awareness, Consistent and Proactive Political System, Engaged Community, Supporting Infrastructure, Financial Capability and Agile Approach need to be addressed. The six focus areas cover the many barriers and enablers for achieving sustainable energy.

An oscillating water column (OWC) wave energy converter (WEC) is a device designed to extract energy from waves at sea by using the water to move trapped air and thus drive an air turbine. Because the incident waves and the force caused by the power take-off (PTO) interact, control of the power take off (PTO) system can increase the total energy converted. A numerical model was developed to study the interaction of an OWC with the water and other structures around it. ANSYS AQWA is used here to find the effects on the water surface in and around the central column of a five-column, breakwater-mounted OWC. For open OWC structures, coupled modes were seen which lead to sensitivity to incident wave period and direction. The frequency-domain displacements of the internal water surface of the central column were turned into a force-displacement, time-domain model in MATLAB Simulink using a state space approximation. The model of the hydrodynamics was then combined with the thermodynamic and turbine equations for a Wells turbine. A baseline situation was tested for fixed turbine speed operation using a wave climate for a region off the north coast of Devon. A linear feedforward controller and a controller based on maximising turbine efficiency were tested for the system. The linear controller was optimised to find the combination of turbine speed offset and proportional constant that gave maximum energy in the most energy abundant sea state. This increased the converted energy by 31% in comparison to the fixed speed case. For the turbine efficiency control method, the increase was 36%. Energy conversion increases are therefore clearly possible using simple controllers. If increased converted energy is the only criterion for controller choice, then the turbine efficiency control is the best method, however the control action involves using very slow turbine speeds which may not be physically desirable.

The electrification of passenger vehicles has been a step towards the reduction of greenhouse gas emissions by automobiles; however, in the United States many plug-in hybrid electric vehicles (PHEVs) and battery electric vehicles (BEVs) must still be plugged in to a grid that is heavily reliant on the burning of fossil fuels to charge. The goal of this thesis is to investigate how to develop a system capable of fully charging a PHEV using only alternative and/or regenerative energy sources. In developing such a system, various alternative and regenerative energy sources were investigated with the intent of reaching a specified daily energy goal; sufficient to charge a PHEV. These energy sources were evaluated based upon criteria such as novelty, ability to reach desired daily energy goal, applicability to BEV/PHEV, etc. The primary technological categories considered include but are not limited to regenerative and solar technologies. The evaluation of technologies indicated that a major opportunity lies in solar technologies, and in particular concentrated photovoltaics. Design alternatives for a concentrated photovoltaic system capable of reaching the desired energy goal are described. The design alternatives utilize Fresnel lenses as a means of concentrating a large area of sunlight onto an array of photovoltaics affixed to a vehicle. Various tracking mechanisms for the concentrating systems have been outlined to meet given design criteria. 3-D ray tracing algorithms have been developed to determine the path of the tracking mechanisms depending upon the time of year and on the geographic location. The same algorithms have been used in conjunction with typical meteorological year data to determine the expected output of the concentrating systems based upon the solar resource and solar angles at a specific place and time. The findings suggest that a concentrated photovoltaic system designed specifically for charging an electrified vehicle may generate sufficient energy over the course of a day to power a typical driver’s trips. However, for such a concentrating system to be commercially feasible there are still many design challenges to be overcome. Design limitations and implications for further research are discussed.