| Author: | Wang, Richard |
| Title: | Sustainability and resilience assessment on renewable energy microgrid dedicated to UNSDG 7 |
| Advisors: | Hsu, Shu-chien (CEE) Poon, Chi Sun (CEE) |
| Degree: | Ph.D. |
| Year: | 2022 |
| Subject: | Microgrids (Smart power grids) Electric power -- Conservation Hong Kong Polytechnic University -- Dissertations |
| Department: | Department of Civil and Environmental Engineering |
| Pages: | 290 pages : color illustrations |
| Language: | English |
| Abstract: | "Affordable and Clean Energy" is Goal 7 of the United Nations Sustainable Development Goals (UNSDGs). This goal aims to ensure access to affordable, reliable, sustainable, and modern energy for all. In alignment with this UNSDG, it is critical to carry out a comprehensive assessment of renewable energy microgrids. Scientific evidence based on actual applications is essential for demonstrating the merits of microgrid solutions. This thesis aims to advance our understanding of renewable energy microgrids by conducting a multi-aspect assessment, covering environmental, economic, technical, resilience, and socio-environmental dimensions. Owing to the multi-aspect nature of the assessment, a wide range of assessment tools are deployed that are specific to each dimension of interest, including life cycle assessment, life cycle costing, building energy modelling, and agent-based modelling. For environmental performance, a comparative life cycle assessment was carried out via a case study of the Town Island Microgrid. The assessment indicates that the Town Island Microgrid is less impactful in 8 impact categories out of 12, compared to 2 electrification options (diesel generator and grid extension). The system energy payback time was calculated to be 9.2 years, while the energy payback time of the diesel generator and the grid extension is 10.1 and 6.5 times longer. On the economic side, an evaluation of 24 renewable energy microgrids worldwide was performed, involving life cycle costing, economies of scale, and net present value. Life cycle costing approximated the investment costs to be 2,135 USD/kW and operating costs to be 0.066 USD/kWh, which showed lower price competitiveness against pulverized-coal and natural gas. Weak savings from economies of scale is expected as the economies of scale factor was close to 0.9. The net present value suggests that a microgrid investment may not be a profitable one. To address the technical dimension, a modelling framework is proposed for examining photovoltaic rooftops with varying roof availability to achieve peak shaving and carbon reduction. The framework was applied to a 10-storey reference office building with respect to Hong Kong's climate. The study analyzed a series of electricity output data for photovoltaic arrays occupying a minimum of 10%, 30%, and the practical maximum of 50%, to correspond to low, medium, and high photovoltaic potential. Strategies to perform peak shaving are proposed. For instance, if a photovoltaic system covers 50% roofs, the optimum strategy for summer would be 09:00 –18:00 (595 kg CO2 per weekday carbon savings), and 09:00 –12:00 & 14:00 –18:00, excluding lunch hours for winter (271 kg CO2 per weekday carbon savings). Resilience is also an important aspect of effective energy management, especially during a crisis such as COVID-19. To understand the impact of work-from-home arrangements, building energy simulations were conducted in which the increased energy demand for a highrise public residential building in Hong Kong was quantified to be 9%. The potential contribution to the increased energy demand by photovoltaic roofs, as an alternative to on-site energy generation, was modelled. Among the 4 first work-from-home periods, the photovoltaic system could potentially contribute to 6.8% to 11% of additional energy demand. During the remaining normal work arrangement time periods, the photovoltaic system could contribute to around 1.5% of total residential units' energy demand when air-conditioning was on, and 3-4% when air conditioning was off. For socio-environmental aspect, an agent-based model (ABM) was developed to analyse postpandemic work-from-home behaviours based on social theories. Scenario simulations were carried out to understand the impacts of environment constraints (specifically family and colleague influences), resource constraints, and personal stress tolerance on work-from-home behaviour. Analysis across all four simulated scenarios reveals that improving personal stress tolerance is the most effective means for achieving more significant community level energy reduction. More agents were willing to work-from-home for consecutive days (≥3 days) as they overcame personal stress and opted for additional work-from-home days. This resulted in a 42% increase in community level energy reduction owing to the reduction in office and transportation energy consumption. Overall, the thesis contributes to sustainable energy research by comprehensively assessing renewable energy microgrids using a wide array of analytic tools and case studies. Policy making recommendations are presented to further promote the adoption of renewable energy microgrids. |
| Rights: | All rights reserved |
| Access: | open access |
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