Department of Building Services Engineering at the the Hong Kong Polytechnic University and the Water Supplies Department (WSD) of the Hong Kong Special Administrative Region Government have come up with a highly novel way of generating hydropower from water supply lines. Tiny – but efficient – turbines are inserted into the pipes that supply Hong Kong with fresh, clean water. There’s not much residual energy to be had from water flows in these pipes, but it is enough to power generators installed external to the pipes. Each turbine generates about 80 volts, but provided enough are installed, then the energy can be used to power the system’s pumps. In full operation, the array of in-pipe turbines are expected to save 700kWh of electricity and reduce 560 kg of carbon dioxide emissions per year.

You can learn more about this great idea here.