| Author: | Wang, Dongshun |
| Title: | Investigation and economic modeling on hydropower generation in residential buildings water supply and drainage system |
| Advisors: | Yang, Hongxing (BEEE) |
| Degree: | M.Eng. |
| Year: | 2024 |
| Subject: | Water-power Plumbing Drainage, House Hong Kong Polytechnic University -- Dissertations |
| Department: | Department of Building Environment and Energy Engineering |
| Pages: | xi, 75 pages : color illustrations |
| Language: | English |
| Abstract: | Hydropower generation, a renewable and clean method, utilizes the kinetic energy of water, through turbines and generators, for electricity production. While traditionally associated with rivers and waterfalls, the potential for hydropower in building water supply and drainage systems, though smaller, is significant. In buildings, water must be pressurized for distribution, with pressure meticulously reduced before entering households to protect appliances, often through relief valves that waste potential energy. Additionally, grey water from non-toilet sources, discharged from upper floors, presents an untapped resource for power generation. Studies have demonstrated the feasibility of in-pipe hydropower generation within these systems, with power outputs ranging from a few to hundreds of watts, depending on hydraulic conditions. Proposals include replacing pressure reducing valves with hydroelectric generators and designing drainage systems with storage tanks and generators to utilize grey water. Despite promising results, research gaps remain, particularly in practical application and community-wide implementation. This study aims to address these gaps by monitoring water use in a Chinese residential community, assessing the hydropower potential, and evaluating the economic feasibility of such systems, offering guidance for future engineering and policy decisions. This research presents three power generation strategies for the water supply and drainage system in the designated community. Subsequently, power generation capacity calculations and economic modeling are conducted for each scheme. Scheme A proposes the utilization of hydroelectric power generation equipment to maximize the potential energy of the municipal water inlet pipe. Scheme B suggests the substitution of the pressure reducing valve in the floor water meter well with hydroelectric power generation equipment. Lastly, Scheme C involves the collection of gray water from upper floors and the utilization of its gravitational potential energy for electricity generation. The measurement of power generation capacity entails on-site data collection, data processing, and theoretical calculations. Ultimately, with a community occupancy rate of 88%, the annual power generation capacities for scheme A, B, and C amount to 733.18kWh, 168.52kWh, and 2211.74kWh, respectively. The subsequent economic modeling conducted in this study employed the Payback Period (PBP) and Net Present Value (NPV) evaluation methods to assess the financial viability of different schemes. The findings revealed that only Scheme A had the potential to generate a positive cash return within its service life. On the other hand, Schemes B and C exhibited a deviation from positive NPV over time due to their annual savings being lower than their annual operation and maintenance (O&M) costs. Under standard scenarios, Scheme A's PBP was estimated to be 11.37 years. However, it is worth noting that this duration could be shortened by increasing occupancy rates, reducing installation costs, and experiencing a rise in electricity prices. Particularly, the PBP of Scheme A was found to be significantly influenced by market electricity prices, as a 10% increase in prices could potentially reduce the PBP to 7.02 years. These conditions indicate that Scheme A demonstrates a high level of economic feasibility. In contrast, Scheme B, despite its substantial initial investment and limited power generation capacity, exhibited a remarkably low NPV of -500,000 yuan over a 20-year period under standard scenarios. Even when the equipment was installed only at the most power-generating locations, Scheme B failed to generate a positive return. Similarly, Scheme C, although more powerful than Scheme B, faced challenges due to its high annual O&M costs and also failed to yield a positive return within its service life. |
| Rights: | All rights reserved |
| Access: | restricted access |
Files in This Item:
| File | Description | Size | Format | |
|---|---|---|---|---|
| 7758.pdf | For All Users (off-campus access for PolyU Staff & Students only) | 6.2 MB | Adobe PDF | View/Open |
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