Hydroelectric power generation is definitely renewable but not always 'green' when you consider all the side effects, especially when it comes to large hydroelectric dams. In the quest to find alternative power sources to replace fossil fuels, the energy that can be harnessed from moving water is leading to some impressive technological advances.
The latest is from Lucid Energy, which has developed a pipe section with a 5-blade turbine that can be installed in water mains when replacing old leaking pipes.
As explained on the Lucid Energy website, " The hydrodynamic turbine has been carefully designed and lab-tested to maximize efficiency and power generation without interrupting the flow of water. As velocities increase, power production increases. Due to the lift-based design of LucidPipe, the system generates power across a very wide range of flow conditions, volumes and velocities".
Riverside, California has been a test site for the LucidPipe, where the fourth generation model is in place. According to Kevin Milligan, the water utility's assistant general manager, the turbine has worked "flawlessly" and generates enough power to run 14 miles of city street lights.
The city of Portland, Oregon is hoping that the generation of power within the water system will alleviate some of the growing costs the city has seen in its delivery of water to residents.This pilot project is slated for completion in June of 2013, and will generate enough power to run 150 homes.
In the past decade water utility costs have gone up 83% in Portland, and an increase of close to 50% is expected over the next 5 years. Revenues should see this system pay for itself in 7 years, after which the proceeds from power sales will belong to the utility.
Though the amount of energy generated from an individual turbine is relatively small, large urban centres have thousands of kilometres of water pipes, much of which is dug up and replaced every year. Read about other innovative Hydroelectric projects.
I am quite sure that the pump that make the pressure in the water network must consume more energy or this is because ther is serious difference of altitude in that network.
It is certainly not free power created from no-where
otherwise we must announce the discovery perpetual movement...
Check out their website, there is a bit more about it. The turbines are gravity fed, and as most cities will have hills, water will go up and down through the system.
Certainly the higher the altitude as you mention would increase the yield, but downhill is downhill, and they are only installed where there is enough pressure through gravity to spin the turbine or there would be no point to it.