Montreal, PQ, Canada
Capture the energy of waste-water from tall and high-rise buildings as it flows down pipes to a reservoir installed just above and connected to a micro hydroelectric turbine before releasing the water in the sewer below.
These turbines are already used in creeks and small rivers… just substitute the creek with a sewer pipe. This is not a complicated idea. The various technological components already exists and are already in use. And there are no environmental impacts.
All that would be required would be to re-configure and assemble them for use in buildings. Some building modifications to accommodate the reservoir and the micro turbine would be required. Every edifice in the world releases a continuous stream of used water. A lot of energy is expended to bring that water up to each tap in each unit in each edifice… why waste the opportunity to recoup the energy from used water flowing down? Each building can easily connect this power source to the grid. Roof top rain water drains could also be connected to the system.
If every tall building in NYC was equipped with a micro turbine the amount of power generated would be significant. Additional small turbines can be installed in the cities sewer system to recycle the energy from the same water that gave power to the building it came from. Enough energy should be created to provide the energy used to pump waste water in to the treatment plants.