The Energy of Flowing Water

The Chinese University has abundant water sources. Nullah water from Kau To Shan nearby passes through the campus to Tolo Harbour. To harness these natural resources, the University uses a hydraulic ram to pump nullah water to storage sites for irrigation and flushing.

Last year the Estates Management Office installed a hydraulic ram pump (photo 1) in the nullah near Orchid Lodge in Chung Chi College. The device transports water to the storage tank by making use of the kinetic energy of falling water. It works somewhat like a hammer rebounding upon impact. The pump has a valve that allows water to flow through this pipe and build up speed. Once the water reaches its maximum speed, the valve slams shut and pressure is built up in the pump. This pressure forces open a second valve linked to the delivery pipe. When nullah water falls past the hydraulic ram, its momentum will lift a tenth of the water to a storage tank located near the Esther Li Building (photo 2).

Hydraulic ram pumps are environmentally friendly and can be used for over 30 years with minimal maintenance. They have been widely used overseas and on the mainland. Yet there are limitations to installation as they need the momentum of water to operate. Only one spot on CUHK campus is suitable for installation. And, during the dry winter months, they can only serve as auxiliary pumps to electric pumps.