Feeling the Pressure: NYC Energy Company Uses Water Pressure to Generate Electricity

Published on February 17th, 2012 | by

by Lauren Bailey

Old wooden water tower in New York CityWhen most people see the water towers that loom over residential areas they typically think of the water pressure in their showers or sinks. But when New York City’s Frank Zammataro — President and Founder of the NYC-based energy company Rentricity — sees a water tower, he sees electricity. Or at least the potential for it.

Water towers bring pressurized water to large metropolitan areas by making use of pressure differentials — the measure of pressure built up as water travels from a higher elevation to a lower one. As it is transported downward the water builds pressure, often in excess of what a receiving station can manage. This pressure is diffused by what are called pressure reduction valve, which reduces the pressure from upwards of 150 pounds per square inch (psi) to the more standard and usable 35 psi.

Though the energy must be diffused, using pressure reduction valves wastes energy that could be recouped. Which is where Zammataro came in.

Working for his prior company on the 40th floor of a midtown office building in New York, Zammataro and his colleagues had a view of the water tower that maintained the water pressure in his building. Eventually Zammataro had an idea that is now slowly changing the clean energy game. Knowing that the tower controlled water pressure, Zammataro wondered if they could be used to spin turbines and generate electricity.

Preliminary research was discouraging for Zammataro; he discovered that the water pressure in high-rise buildings wasn’t strong enough to push a turbine. But a meeting with Rensselaer Polytechnic Institute professor gave him the direction he needed.

The professor explained how pressure reduction valves (PRVs) worked and how much energy they wasted — and then Zammataro had his solution. By replacing the PRVs water receiving stations use to diffuse pressure with an impeller — the kind of rotary turbine generator found in dams and used to generate electricity — he could effectively regain the energy lost in the pressure reduction.

Though the wattage output of Zammataro’s generators is comparatively small (next to power plants), they do provide enough electricity to cover up to half of a water utility facility’s energy needs, which means that half the electricity and energy it took to power the facility can now be used to meet other needs. This could mean a substantial step forward in green technology, and represents yet another great way new enterprises are rethinking our energy practices to reduce our carbon footprint and minimize waste.

Lauren Bailey writes for accredited online colleges. She welcomes your comments at her email Id: blauren99 @gmail.com.

Water tower image via Shutterstock


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