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Faculty of Engineering and Built Environment

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    Sustainable energy transition and optimization of grid electricity generation and supply
    (2024-05) Kabeyi, Moses Jeremiah Barasa; Olanrewaju, Oludolapo Akanni
    Clean and low-carbon energy sources and technologies have emerged as a critical driver in delivering the energy transition and achieving net zero-carbon emissions. All energy sources and power systems produce greenhouse gases (GHGs) and hence they contribute to anthropogenic greenhouse gas emissions and resultant climate change besides contributing to other negative environmental impacts. Energy sustainability remains a major challenge globally due to current heavy reliance on depletable and polluting fossil fuels for most of global energy needs. This study examines the energy transition strategies and proposes a roadmap for sustainable energy transition for sustainable energy planning and grid electricity generation and supply in wake of commitments made by the world community to the Paris Agreement aimed at reducing greenhouse gas emissions and limiting the rise in global average temperature to 2oC and preferably 1.5oC above the preindustrial level and realisation of the sustainable development goal of the United Nations. The sustainable transition strategies typically consist of three major technological changes namely, energy savings on the demand side, generation efficiency at production level and fossil fuel substitution by various renewable energy sources and low carbon non-renewable sources like nuclear power and carbon emission reduction strategies like carbon capture and sequestration and a conversion from high carbon fossil fuels like coal and oil to natural gas which remains the cleanest fossil fuel. The study demonstrated that decentralised generation with application of both demand side management and behind the meter management (BTM) strategies are effective measures to increase the use of renewable energy resources which are often locally available leading to higher uptake of renewable energy sources and conversion of consumers to prosumers making the transition economically sustainable. Waste to energy options have a significant potential to contribute to the energy transition e.g. use of biowaste for biogas production, slaughterhouse waste biodigestion for biogas and electricity generation and waste treatment and disposal, waste heat recovery from used geothermal for extra power generation and reinjection to improve the reservoir sustainability and use of bagasse and sugarcane trash for grid-based power production in sugar factories. Therefore, domestic, and industrial scale waste to energy conversion can enhance the economic sustainability of waste management process by offering useful energy substitutes for fossil fuels and enhanced energy security through decentralisation of generation. Whereas sustainable development has social, economic, and environmental pillars, energy sustainability is best analysed by five-dimensional approach consisting of environmental, economic, social, technical, and institutional/political sustainability to determine energy resource sustainability. The study recommends the adoption of sustainability-based planning for energy development and optimisation of electricity generation and supply where energy sources are analysed and ranked based on the five dimensions of energy sustainability instead of Least Cost Development Planning (LCDP) often applied by many countries. On this basis, the sustainable energy transition and optimisation of power generation will rely on both renewable and non-renewable energy since both have an important role in the realisation of the energy transition plans even though the desire is to shift entirely to renewable energy sources by the year 2050. The sustainability of various energy sources was assessed with hydrogen, wind, solar, sugarcane bagasse and cane trash, biogas and ocean energy technologies proving to be among the most sustainable renewable energy and sustainable sources. The study also examined various power plants and energy conversion systems for electricity generation in terms of their specific role and potential in grid-based power generation with hydro power plants, geothermal, nuclear, fuel cells, raking high on performance indicators like load and capacity factors making them ideal for base load power supply. Diesel engines and gas turbines using cogeneration and dual cycle systems powered by cleaner fuels like natural gas, hydrogen and biomethane will play an important role in supplying intermediate and peak load power. The study highlighted enabling technologies and concepts in the energy transition which include decentralisation of generation, cogeneration and trigeneration, demand side and behind the meter management microgrids and smart grid technologies, energy and generation planning and optimisation models, energy storage, electrification of transport and use of electric cars as decentralised electricity sources through the V2X technologies like the G2V and V2G, and carbon capture and sequestration for emissions reduction in fossil fuel power plants making them more sustainable. The study classifies electric vehicles as distributed power plants and variable loads with extensive use of energy storage while sugar cane bagasse is noted as a sustainable energy resource for power generation by cane sugar factories by application of more efficient grid connected cogeneration power plants. The study identified long project gestation period as the main factor limiting nuclear and geothermal energy deployment and recommends the adoption of modularised wellhead generators and small modular nuclear reactors (SMRs) as a solution to enhance exploitation of these sustainable energy and technologies through faster deployment with high degree of flexibility. Biogas and biomethane demonstrated significant potential as renewable energy sources for power generation and substitute fuels in all applications of fossil natural gas. The study recommends sustainability-based planning for the energy sector and power generation and use of both renewable and non-renewable but sustainable sources of energy, adoption of smart energy concept by all sectors and investment in energy technology and infrastructure development for hydrogen and other promising energy sources like ocean thermal, wave and tidal energy and the conversion of the transition from the traditional to smart grid systems and a shift from centralised to decentralised power generation. Since the transport sector accounts for a significant portion of the global greenhouse gas emissions, electrification of the transport sector and coupling with the power sector is a key strategy recommended for the transition with the smart grid and microgrids playing an enabling role. Since energy sources and generation technologies have associated emissions occurring at different sections of the lifecycle, the use of lifecycle costs and emissions are helpful in long term energy and generation planning which demonstrate that renewable sources and nuclear are the most sustainable when analysed within the five dimensions of energy sustainability, but with the non-renewable sources playing a critical role as dispatchable sources for sustainable grid power generation, while the smart grids and use of energy storage can increase the uptake of variable renewables to as high as 95% to 100% up from a low of 20-25% uptake of variable renewables with the traditional grid. This will significantly help the world in achieving the global emissions and climate targets as. stipulated in the Paris Agreement as well as the sustainable development goals (SDGs). Graphical Abstract The overall objective of the study was to provide solutions to build global energy systems based on renewable and sustainable energy resources and optimise power generation and consumption by use of sustainable energy resources and generation technologies based on the five dimensions of energy sustainability. A sustainable energy system should intergrade electricity and other sectors through smart electricity grids, smart gas grids and smart heat grids as demonstrated below.
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    Application of DMAIC to improve energy consumption in a commercial building
    (2021-03) Kanyinda, Kabuya; Lazarus, Ian Joseph
    Improving energy use in a commercial building has become the subject of great importance in organizations worldwide. Improving energy usage refers to the efforts to reduce energy consumption. Reducing energy consumption in commercial buildings can be accomplished through continuous supervision using appropriate managerial techniques. Commercial companies are required to use energy more efficiently and participate in energy improvement. This study seeks to improve electrical energy consumption in commercial buildings by Analysing the electrical data consumption and identifying the factors that contribute to high consumption using Six Sigma DMAIC (Define-Measure- Analyse-Improve-Control) problem solving methodology. A case study was used to validate the DMAIC framework. Two years of electrical consumption data of a case study done from January 2018 to December 2019 was collected and analysed. The study revealed an average increment in energy consumption of 3.9 %. The outcomes using statistical Pareto chart showed that the boiler is the highest significant energy user in the building with 38.3% due; followed by the kitchen with 24.2 %, followed by DB A and lifts with 20,1 % and the rest with 17.37 %. After the campaign of DMAIC, there was a reduction of 6 % in boiler consumption which was 2.3 % reduction of total consumption of the month for the building. Therefore, the study successfully demonstrates how Six Sigma DMAIC methodology can be applied to improve electrical consumption in a commercial building and reduce its related costs.
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    Analysing South Africa’s automotive energy consumption : application of index decomposition analysis
    (2021-01) Machivha, Rofhiwa Tevin; Olanrewaju, Oludolapo Akanni
    This research focuses on applying the Index Decomposition Analysis (IDA) to South Africa’s automotive industry to decompose energy consumption and further make use of regression analysis to understand how it relates to the economy. South Africa has been going through an energy crisis, which has resulted in ongoing load shedding as a way to manage this crisis. Looking at South Africa’s energy generation, it can be noted that the entire country depends on Eskom as the main supplier and of electricity, but it is unable to keep pace with the demand. The results of the research show that there exists a nexus across all segments between energy consumption and GDP; furthermore, the decomposition results show that energy consumption in some years experienced a reduction. However, it can be seen that an increase in energy consumption year on year is predominant; this then suggests that the reductions experienced were the result of a special event; hence, it can be deduced that overall energy consumption has increased slightly. The increase is as a result of the activity effect which contributed the most towards this whilst the structural effect yielded a negligible contribution. Lastly, the intensity effect contributed to the reduction in energy consumption as a result of sectoral shifts; this reduction contributed towards keeping the overall increase in energy consumption low. This study aimed to outline the differences in energy consumed during the production of different vehicle classes, citing various factors responsible for the changes in energy consumption during vehicle production, raising awareness with manufacturers on the impact industrial energy consumption has on the national energy grid and on advising medium to large manufacturers to become suppliers.
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    An assessment of the impact of selected construction materials on the life cycle energy performance and thermal comfort in buildings
    (2021) Haripersad, Rajesh; Lazarus, Ian Joseph; Singh, Ramkishore; Aiyetan, Olatunji Ayodeji
    South Africa is a developing country with various construction projects that are being undertaken both by government and the private sector. The requirements for the construction of energy-efficient buildings as well as the selection methods for providing construction materials have hence become important. Energy efficiency improvements needs to be implemented in the construction of these buildings in order to decrease energy usage and costs and provide more comfortable conditions for its occupants. Previous studies revealed that most of the focus for improving energy efficiency in buildings has been on their operational emissions. It is estimated that about 30% of all energy consumed throughout the lifetime of a building is utilized as embodied energy (this percentage varies based on factors such as age of building, climate and materials). In the past this percentage was much lower, but with increased emphasis placed on reducing operational emissions (such as energy efficiency improvements in heating and cooling systems), the embodied energy contribution has become more significant. Hence, it is important to employ a life-cycle carbon framework in analysing the carbon emissions in buildings. The study aims to augment energy efficiency initiatives by showcasing energy reduction strategies for buildings. The study assessed the thermal performance of selected construction materials by analysing different buildings using energy modelling program, EnergyPlus and TRNSYS. The parametric study was set in the central plateau region of South Africa and was performed to determine appropriate energy efficiency improvements that can be implemented for maximum savings. A life cycle cost analysis was performed on the selected improvements. The models created are representative of the actual buildings when simulated data is compared to recorded data from these buildings. Results showed a significant variation in energy and construction costs with varying construction materials over the buildings’ life cycle. Findings suggest that there is a significant reduction in energy usage when simple efficiency measures are implemented. The study recommends the use of different energy efficient building materials and the implementation of passive interventions in the constructing of buildings; the thermal performance of a building be optimized to ensure thermal comfort and the developed model be adopted for use in the engineering and construction industry for the reduction of energy consumption.