Portland Is Recycling Power from its Water System

Water is heavy. It can produce a great deal of power as it flows downhill. People have been taking advantage of that fact for centuries. At the same time, it takes quite a bit of power to pump water. Indeed, water utilities are among the largest consumers of energy in a given area. Once that energy has been spent, that is generally the end of the story. But a company, Lucid Energy, has come up with a way to recover some of that energy from water as it passes through a utility’s pipes in the network.

Lucid describes itself as a provider of “in-conduit hydropower technology.” In partnership with the Northwest Pipe Company, it developed a lift-based turbine that incorporates into a section of steel pipe and commercially calls the design the LucidPipe Power System. Lift-based turbines, as opposed to drag-based turbines, use airfoil-shaped blades that utilize the lift generated by the passing fluid to pull the blades along, and are linked to generators to produce electricity.

These turbines generally have a vertical axis, not unlike the egg-beater-shaped Darrieus rotors used in windmills. As long as water is flowing through the pipes, power is generated. The power is then sent back into the grid where it can, among other things, be used to pump water.

A lot has been said about the energy-water nexus, but this is coming at it from a different angle. This is not perpetual motion or any violation of the laws of physics, but rather a simple recapturing of some of the energy, which comes from some combination of pumping and gravity that goes into the system.

The systems have been commercially available since 2012, and in early 2015 Lucid installed one for the Portland Water Bureau (PWB) in partnership with PG&E. The LucidPipe Power System uses the flow of water inside the PWB pipeline to spin four 42-inch, 50-kW turbines. The system is expected to produce 1.1 million kWh of electricity per year for PG&E.

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The turbines are available for pipe diameters ranging from 24 to 60 inches, with the 60-inch model producing 100 kW. Best performance is achieved with a water velocity of at least 4 ft/s. According to company literature, it is helpful, in some cases, to reduce the pipe diameter in the section where the turbine is installed to assure adequate velocity.

The company claims the turbines have no impact on the operation of a piping system, though there is a pressure drop of 5 psi to 6 psi. Gauge pressures ranging from 38 psi to 49 psi are required to maintain the rated output.

Lucid has a similar system installed at the Riverside Public Utilities in Riverside, Calif., which won the Outstanding Energy Management Award from the California-Nevada Section of the American Water Works Association in 2011.

“It’s pretty rare to find a new source of energy where there’s no environmental impact,” Gregg Semler, Lucid CEO, told Fast Company. “But this is inside a pipe, so no fish or endangered species are impacted.”

And it’s a clean energy system that is not dependent on the weather. In coastal areas where fresh water is scarce, the power the system generates could be used for desalination.

RP Siegel, PE, has a master's degree in mechanical engineering and worked for 20 years in R&D at Xerox Corp. An inventor with 50 patents, and now a full-time writer, RP finds his primary interest at the intersection of technology and society. His work has appeared in multiple consumer and industry outlets, and he also co-authored the eco-thriller Vapor Trails.

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Correction: A previous version of this article misidentified the Western Municipal Water District in Riverside, Calif. It is actually called Riverside Public Utilities.