A shower on the upper floor of a high rise building can provide magnificent water pressure — a liquid shiatsu massage. A New York City startup has started tapping into that intense water pressure at treatment plants, reservoirs and factories, converting the excess into electricity.

The idea for the startup, Rentricity, began following 9/11, when president and co-founder Frank Zammataro had to relocate to a conference room that overlooked a rooftop water tower. Zammataro, who had specialized in information technology for Merrill Lynch, saw opportunity in the towers that maintain water pressure in tall buildings, he told writer David Ferris for Ecomagination.com.

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When water utilities create reservoirs at a high elevation to serve populations living in lower-lying cities, they install pipes for the water to flow down hill. Zammataro explained to me that the water's speed increases so much while flowing downhill that it has to be slowed down to prevent it from exploding when a customer turns on the faucet.

Utilities reduce that serious water pressure using a specialized valve. Installed in the pipe, the valve dissipates the pressure and slows the flow by squeezing the water column. Those standard valves also creates waste heat and pressure in the process, Zammataro said.


Rentricity makes a turbine-generator device called "Flow-to-Wire," that's basically a wheel connected to a shaft and generator. Water pressure gets dissipated and the flow is slowed, but as the water moves through the wheel, a generator creates an electric field.

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"The concept and the technology is quite simple," Zammataro said. Rentricity installed its technology, which it says is made affordably using off-the-shelf parts, at a water treatment plant in Keene, New Hampshire. The public works director told Ferris that the move has cut the plant's energy bill in half.

Recently, the company did an installation for Pennsylvania American Water at their Oneida Valley water treatment plant, Zammataro told me. "This 25-kilowatt 'Flow-to-Wire' system offsets approximately 15% of the power needed by the plant to process raw water into clean drinkable water for the local community," he said.

Credit: Nick Koudis/Getty Images

Photo: Rentricity's installation for Pennsylvania American Water in Butler, Pa. Credit: Ang Zhu, Rentricity Inc.