New York City to Explore Electricity from Water Mains

It sounds so sensible, you have to wonder why everybody isn't already doing it: Tap the excess pressure found in many urban water mains to drive small turbines that could feed electricity into the grid, block-by-block. Often such pressure has to be relieved by means of specially installed valves that do no work. Why not exploit it to generate power?
It took a New York City wireless company executive, musing idly about emergency power shortly after 9/11, to dream up the idea of electricity from water mains. The startup he founded and leads, Rentricity, has been attracting attention and interest locally. It has obtained modest R&D funding from the New York State Energy Research and Development Authority (NYSERDA) and is a tenant of the  New York University Polytechtechnic Institute Incubator that was started by the New York City Accelerator for a Clean and Renewable Economy. On 1 May, NYC Mayor Michael Bloomberg signed into law a city council resolution calling on New York to do an 18-month study of the feasibility of widely deploying electricity-from-water-main technology throughout the city.