3. Electronic Theses and Dissertations (ETDs) - All submissions
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Item Assessing potential for net-zero energy building retrofits in commercial buildings using on-site photovoltaic (PV) generation: a case study of Durban-South Africa(2019) Davies, GarethRetrofitting existing buildings towards NZEB (net-zero energy building) offers significant benefits in terms of reducing operational electricity consumption and operating costs as well as reducing GHG emissions. The increased efficiency and economic cost competitiveness of renewable energy technologies, as well as the advances in building science and energy modelling, continue to evolve along with the increased demand for energy security, thus allowing for advancement of NZEB. But to what extent is NZEB viable for all existing commercial buildings, and what are the technical and contextual parameters that would influence the potential of NZEB retrofits? The study substantiates on these questions via a simulated performance-based analysis of four existing commercial buildings in Durban, with energy modelling and simulation as the primary data sources. The simulation data were then applied towards the assessment of the potential of retrofitting for NZEB based on passive interventions in conjunction with energy-use optimisation of active/mechanical systems and integrated RE technology in the form of site PV. The study demonstrated a reduction of 27% - 56% in overall grid-electricity consumption and carbon emissions across the case study samples. Lower FAR buildings achieved greater percentage reductions in grid-electricity consumption due to less site shading combined with larger site-area (for PV) to net floor area ratio. Longer operating schedules were also found to increase annual energy consumption while also being better suited for on-site PV generation due to consistent levels of self-consumption. User-density was found to have less significant impacts on overall electricity consumption. Payback periods for NZEB-targeting interventions were enhanced by the recent introduction of the RE tax allowance, which reduced overall payback periods by 2-3 years with two of the case study buildings achieving 4-6 year yields which is considered to be within an acceptable range based on prevailing efficiency and cost levels of the assessed interventions. The study found that the efficacy and practicality of on-site generation PV is limited by grid constraints for building use-types with a high export balance, and for certain high-density sites due to high shading levels. The study recommends smart-grid integration which would connect buildings that can benefit from either consuming or exporting RE and thus ensure annual energy consumption and GHGemissions in the sub-sector could be brought into line with the 38% reduction compared to the 2050 Nationally Determined Contribution GHG emission reduction targetItem Innovative green finance for renewable energy interventions in gap housing for South Africa: a case study of rooftop PV for Windmill park residential complex Johannesburg(2018) Kaluba, BesaIn light of the current rapid growth of the gap housing market segment, the electricity crisis facing South Africa and adverse impacts of coal-based electricity generation on climate change, this study helps to qualify the viability of integrating rooftop solar pv in gap housing towards improving gap housing affordability and mitigating power challenges currently facing the country. Using a case study approach, the study addressed four key research questions which are: affordability of housing in the gap housing market in South Africa, estimating the generation potential from the available rooftop space in the case study area, establishing a business model for integrating rooftop solar pv in the gap housing market, and the extent to which rooftop solar pv can augment housing affordability in the gap market segment. Various software and web-based applications were utilized to establish the solar pv generation potential of the study area. From the available rooftop space of 36 593.65m2 in Windmill Park Estate, a production potential of 7 848 124.71 kW/h per annum was estimated. This is sufficient to make the estate a net-zero grid electricity consumer. Based on these findings, two scenarios were analysed using the net present value (NPV) to determine the profitability and the business model for integrating rooftop solar pv in the case study. Exporting only 50% of the generated electricity proved the most viable scenario with thirteen to fourteen year payback period. Affordability to purchase housing in the estate increased by R 399,633.30 in the twentieth year and rent affordability increased by R 706.25 per month in the first year. This understanding of the extent to which rooftop solar pv can augment housing affordability is important to encourage, guide and inform policy makers and other stakeholders in the formulation and deployment of various gap housing finance schemes that support such interventions.Item Determinants that influence renewable energy investments(2018) Wrigley, CharleneThe Kyoto Protocol, Global Climate Change Agenda and imperative to reduce greenhouse gas emissions has gained significant traction recently as decision makers attempt to mitigate the impacts of climate change. Energy that is produced from non-renewable energy sources, such as fossil fuels, is a significant contributor to greenhouse gas emissions, and by displacing non-renewable energy production and consumption with renewable energy production, greenhouse gas emissions can be reduced. This is particularly relevant to the mining industry, which is a significant consumer of energy, particularly energy from non-renewable fossil fuel sources. Consumption of renewable energy for mining related activities presents a cost saving opportunity for the industry and could support mitigating the effects of climate change. This research aimed to identify the main determinants that influence decisions in energy investment projects, and specifically, to determine the most influential determinant in energy investment decisions, particularly in the mining industry. Through interviews of subject matter experts in the mining industry, sustainable development, renewable energy and renewable energy project investment and finance, the results suggest that Life of Operation, i.e. life of mining asset or operation, was the most influential determinant in making energy investment decisions. Security of Energy Supply in which cost, reliability and availability are secured through the energy investment closely follows as the second most influential determinant. The Global Climate Change Agenda may create an enabling environment for renewable energy investments, however the key drivers in such decisions are the financial aspects of the investment.Item Decentralised electricity generation through rooftop solar photovoltaics (PVs) in Zambia : a case study of the engineering institute of Zambia (EIZ) office building project, Lusaka(2018) Samunete, JosephWhereas there has been significant study and development of national strategic plans on electricity generation from renewable energy in general in Zambia, specific studies and research on decentralised electricity generation via rooftop solar PVs from buildings and their potential to enhance Zambia’s electricity generation goals have not systematically been done. The study applies a case study of the Engineering Institute of Zambia office building that is at construction stage but is determined to incorporate a rooftop solar PV system. Using DesignBuilder and Energyplus simulation software, the building was modelled and analysed for this potential. In addition, based on interview data from various experts and secondary data from national plans, the study evaluated policy, regulatory and market frameworks which could catalyse the increased deployment of such systems in Zambia. Using financial analysis tools of payback period, return on investment and net present value the study undertook a number of business case scenarios in order to conceptualize a responsive business model. The study finds that from the initial estimate, the available roof space had the capacity to net out the baseline annual electricity consumption of 287,707kWh and generate a surplus of 63,519kWh/year before optimisation. Optimisation of the baseline consumption through a combination of two viable energy efficiency interventions reduced the baseline annual consumption by 35% to 186,904kWh with related payback period of nine years, ROI of 518% over a 25 year analysis period and a NPV of 623,344.00 ZMK. Based on these findings, three business case scenarios for the solar PV system were analysed and two out of the three were adopted. One scenario assumed a net-zero building and another one assumed that the surplus electricity generated on non-business days is exported to the grid were adopted. Following this finding, a business model centred on an integrated energy service company (IESCo) was identified as the most appropriate model to respond to the uptake barriers of this technology and thus leverage on the emerging progressive support mechanisms. The overall findings of the study thus support the working hypothesis of the study which deemed that through the framework of a responsive business model, decentralised electricity generation through rooftop solar PV can greatly enhance energy security and mitigate GHG-emission for Zambia.Item Solar PV for decentralised generation for commercial buildings in Nigeria: a case study of the architecture building at Kodi state poltechnic(2017) Adejoro, Ipinmoroti SamuelThe centralised energy generation system has been constantly criticised for not meeting the demand of Nigerian consumers. Recent studies on Nigeria’s energy crises suggest that there should be an urgent adoption of decentralized generation (DG) as a means of alleviating energy poverty in the country, and as a way of reducing greenhouse gas emission (GHG) from the popular fossil-fuel based standalone generators. However, businesses today are anxiously trying to find ways to lower their energy related expenditures. In line with these assertions, and using a case study of the Department of Architectural Office Building (DAOB) to incorporate rooftop solar PV system, the study uses a Design Builder and Energy plus simulation software to model and analyse the DAOB. This study is based on primary and secondary data sources. The study assessed policy regulatory and market structures which could stimulate the increased deployment of such systems in Nigeria. The electricity bills for one year reported an annual consumption of 12,407 kWh, at the cost of N297, 762 ($945) and likewise the cost of operating a building on diesel generator for a period of one year was calculated at N2, 688,000 ($8,513) while the status-quo baseline energy consumption of the building from simulation and the cost implication per annum was 69,733 kWh and ₦1,673,592 ($5,579) respectively. Optimisation of the baseline consumption through a combination of three feasible energy efficiency initiatives reduced the baseline annual consumption by 47% from 69,733kWh to 37,298 kWh. The roof had the capacity to generate 155,347kWh which could cover for both the baseline and the optimised annual electricity consumption. The analysis revealed further that the roof could generate a surplus of 118,045 kWh/annum based on the optimised energy consumption. Using financial analysis tools of payback period, return on investment and net present value, the study undertook a number of business case scenarios to establish a viable business model. Based on the financial analysis performed, a Solar Power Purchase Agreement (SPPA) business model was identified as the most suitable to overcome the barrier of upfront cost.Item Simulation of a hot mirror parabolic trough solar collector receiver(2018) Kaluba, Victor SiulutaParabolic trough solar collectors (PTSC) are currently the most mature solar collecting technology, applied commercially for electricity generation. High input temperature in power plants are desired for improved efficiency and help reduce electricity costs. However, at high temperatures, heat losses through radiation increase significantly. Thermal radiation transfer is the dominant heat loss mechanism in PTSC receivers operating at high temperatures. In existing systems, the radiation losses are reduced by using a selective absorber coating placed on the absorber pipe. It has optical properties that suppress infrared radiation (IR) emissions. The material absorbs well in the solar wavelength range (0.3 to 2.5 um ) but emits poorly in the infrared (IR) wavelength range. However, the material degrades at temperatures beyond 400oC resulting in high IR emission. This study developed a theoretical framework to characterize a different approach, alternative to the selective coating in reducing heat losses. This is the use of a hot mirror coating in a PTSC receiver. The coating is placed on the inner surface of the glass cover to reflect infrared radiation emanating from the absorber pipe back for reabsorption. The hot mirror is transparent to solar radiation and reflective in the wavelengths above 2.5 um. The formulations developed described the thermal interactions in a hot mirror coated PTSC receiver. To describe the heat loss reduction mechanisms, the study modelled theoretically the long range thermal radiation interactions inside the receiver unit. The model used discretization of the active surfaces to account for all the dominant radiation interactions. Different simulations scenarios were done to predict receiver performance. The performance of various candidates for hot mirror coating (ITO, Gold and Silver) were investigated. The effects of variation of some hot mirror optical parameters on overall plant efficiency was also investigated. The simulation was validated using other simulation works and experimental data. The results showed a close match with a discrepancy of 0.7%. High HTF temperatures were attained using hot mirrors. ITO gave the highest HTF temperature. The hot mirror thermal stability is not compromised since the glass cover stays cooler than the absorber pipe (< 400oC). The glass cover temperatures were far less than the absorber pipe temperatures. Even with the higher temperature of ITO (500oC), the glass cover never reached above 400oC. Solar transmissivity for the hot mirror materials is as important as the need for high HTF out temperatures.Item Mitigating exclusionary greening of South African cities through participation of indigent households in renewable energy: the case of Galeshwe settlement in Sol Plaatjie municipality, South Africa(2018) Tyabashe, NomondeBased 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.