For decades in China, hydroelectricity has been used on a large scale to generate power. Now, engineers from the PolyU’s Department of Building Services Engineering and the Water Supplies Department (WSD) of the Hong Kong Special Administrative Region Government are working on using water mains to create electricity. Hong Kong has a network of pipes that stretch 7,800 km that need to be monitored constantly to ensure that they are clean and functioning properly. To run the observation equipment, small turbines are placed in pipes to harness the motion of water passing by. Each little turbine is able to pump out 80 volts, enough energy to power about four fluorescent light bulbs.
Water mains present a challenge for designers looking to turn them into sources of power. They are narrow in diameter, and therefore hold much less water volume and potential energy. Engineers, from PolyU led by Prof. Hong-xing Yang from Department of Building Services Engineering have made an incredibly efficient spherical turbine that is able to capture the energy of moving water. It consists of a small hydroelectric generator which dips into flowing water to reclaim residual pressure. Using only eight blades, the turbine possesses a hollow central rotating shaft that helps to minimize energy loss. To increase the amount of energy in the water, the team placed a block at the opening of the pipe to compress and accelerate flow. To protect the quality of the drinking water, the turbine does not have parts that require lubrication.
The turbine has been tested in a number of locations across Hong Kong. When fully installed, an array of turbines are expected to save 700kWh of electricity and reduce carbon dioxide emissions by 560kg each year.