Water companies are an untapped source for potential power generation, and a New York City startup is working with a Palos Verdes area water company to put some of that power to good use.
ReWire's colleague Ucilia Wang at GigaOm noted the work of the startup company Rentricity today; the firm works with water utilities to capture some of the energy that's lost when high-pressure water from mains is stepped down to lower-pressure distribution pipes. Rentricity's "Flow-To-Wire" technology harnesses that change in pressure by running the water through generators, which feed power into the grid -- thus taking advantage of energy that would otherwise be lost.
In an interview posted yesterday on the website of CEOCFO Magazine, Rentricity founder Frank Zammataro explains his company's technology:
Very simply, water is travelling downhill from a reservoir at a high elevation; it may be 200 feet above the city that it is serving. Water utilities use that elevation to help move the water. It literally just goes downhill, and as it is coming down in a solid pipe, it is gaining speed. When it gets to the bottom, or near the city, water utilities have to deploy a valve, which is a device that stops the water, literally just causes the water to slow down by closing the valve. It creates friction at that point and that friction causes wasted heat or wasted energy. That is the point in the water system where Rentricity can deploy its Flow-to-Wires technology, actually spin a wheel that has been connected to a generator, which creates clean electricity.
As it turns out, the California Water Service company has been working with Rentricity for a few years to install just such an energy recovery unit at one of its pressure reducing valves in the Rancho Palos Verdes area of Los Angeles County. Slated to go online in 2013, the 350-kilowatt generator will significantly cut the utility's energy footprint as it brings water to residents and businesses. A 2009 estimate by the California Public Utilities Commission Division of Ratepayer Advocates said the project should cost ratepayers about 21 cents each month, a figure that will likely drop as the cost of grid power rises.
Though its 350-kilowatt capacity will make the Palos Verdes installation Rentricity's largest to date, that capacity of generator may not sound very large. It's about one-thousandth the capacity of some of the large solar projects that are now being built in the California Desert, for instance. But this is energy that would otherwise be wasted, and that there are thousands of similar water pressure control stations across the state. It's just an example of how rethinking the way we manage our complex industrial society on an every-day basis can help us cut our power consumption dramatically.