Mr. Ho Chi CHEUNG (year 2 student in Mechanical Engineering) won the champion in the HKIE Enginpreneurs Award 2021 - Young Innovators for the project, Micro-hydropower system by domestic sewage in buildings.
This project is an idea to use the potential energy of domestic sewage to generate electricity. As skyscrapers are everywhere in Hong Kong, engineers can collect domestic sewage from each floor. In Hong Kong, Drainage Service Department has to deal with 2,800,000 cubic meters of sewage every day according to the data in 2017-2018. We can use these large amounts of water to generate power. To utilize these wasted potential energies, micro-hydropower generators can be installed on the ground floor.
This system can be installed on any building with a drainage system. The modification of the pipeline needs to be carried out near the ground floor, but this is only a small change compared with the entire existing drainage system.
There are two ways to install micro-hydropower generators: The first method is to install a hydropower generator in the power generation room, introducing domestic sewage different pipes into this room through different pipes and hitting the turbine. The potential energy carried by domestic sewage is converted into kinetic energy. The water flow will drive the turbine blades to move. The advantage of this method is that maintenance becomes easier because only one turbine in one power generation room has to be cleaned and inspected. The second method is to install small turbines in the pipeline. The advantage of this method is that the potential energy is maximized because the water flow can directly hit the turbine in the pipeline.
Both methods can adjust the water flow to some extent to produce the maximum speed of the turbine blades. In this case, a Francis turbine can be used because it is suitable for low head applications from about 40m to 600m.
The target users of this project are people living in densely populated buildings. Residents in the building can share the cost of the power system, increase the flow rate of domestic sewage, and maximize the power generation. The generated electricity can be used for internal consumption or sold to the electricity company by connecting the system to the power grid.