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July 3, 2017 Featured Articles, MainFeature

From Waste Heat to Essential Electricity

Overview Hydraulics Lab UNR
Overview of in-conduit hydro-generator, pressure reducing valves, and other equipment, in the hydraulics lab
of the Civil and Environmental Engineering department at the University of Nevada, Reno
–M. Etezadi-Amoli Photo

From Waste Heat to Essential Electricity

NEXUS research harnesses lost energy in water delivery systems to create electricity

By Jane Palmer
July 2017

In every water delivery system throughout the United States, pressure-reducing values (PRVs) continually lower the high pressure of water so that it is suitable for customer use. NEXUS scientist Dr. Mehdi Etezadi-Amoli, a professor of electrical and biomedical engineering at the University of Nevada, Reno (UNR) is investigating the potential for this process to also generate electrical power, using waste energy from the reduction process. To do this Etezadi-Amoli and his team have looked at the efficiency of the water delivery system in Northern Nevada and proposed a scheme to convert the wasted energy into electricity.
“This is a renewable energy source that converts the wasted energy in PRVs to electricity,” Etezadi-Amoli says. “Water distribution stations can use the generated power to supply their local loads and even sell the extra amount to power companies.”
Mehdi Etezadi-Amoli, University of Nevada, Reno
Mehdi Etezadi-Amoli, University of Nevada, Reno
–M. Etezadi-Amoli Photo

Creating a Diversion

Any water delivery system requires pumping stations to increase water pressures in supply mains for firefighting, high-rise buildings, and to maintain the water supply in water towers and storage tanks. For domestic systems, however, PRVs are required where the municipal water main’s pressure is more than 80psi.
“But these PRVs waste the energy during this conversion and our objective is to capture this waste energy,” Etezadi-Amoli says.
The water in delivery systems is at a higher pressure than is ideal for customer use and the role of pressure control valves is to reduce this pressure. Some of the energy loss across the PRV can be converted to electricity using small hydroelectric systems, known as in-conduit hydro-powered generators.  By installing a parallel pipeline and a turbine, the flow of water at high pressure can be used to generate hydroelectric power. To test out this theory, Etezadi-Amoli and his team have designed a laboratory-scale platform for investigating the in-conduit hydropower generators that capture the waste energy created by the pressure reducing valves.
The team installed the in-conduit hydro-generator, pressure reducing valves, and other equipment, in the hydraulics lab of the Civil and Environmental Engineering department at UNR. They then developed a control and operation scheme on the laboratory-scale platform and evaluated its performance under different operating scenarios.
Developed Operation Scheme
Developed Operation Scheme
–M. Etezadi-Amoli
“Although this concept has been implemented for very large scale systems, it is exciting that we were able to build a small scale laboratory demonstration unit that involves hydraulics, electrical power generator, power electronics, storage, and computer control for improved efficiency of the conversion scheme,” Etezadi-Amoli says.
SideView Hydraulics Lab, University of Nevada, Reno
Sideview of the in-conduit hydro-generator, pressure reducing valves, and other
equipment, in the hydraulics lab of the Civil and Environmental Engineering department
at the University of Nevada, Reno.
–M. Etezadi-Amoli Photo

Saving and Storing

One challenge for such a system is the variable water usage of domestic users. For example, people may only choose to take a shower at a certain time of day.   “If we don’t have any flow, we don’t have any energy,” Etezadi-Amoli says. “If you utilize this system on a very small scale like we did for our water distribution system, it is an intermittent energy system.”
By converting the electrical power into Direct Current (DC), the researchers can store energy in batteries. “The generated power can be stored in the storage units and used later to provide a fixed power, “Etezadi-Amoli says.
Alternatively, the energy can be converted into alternating current (AC) to be pumped back to the power company or the distribution system. Additionally, other renewable energy sources such as wind and photovoltaic can be integrated into the facility for improved power quality,” Etezadi-Amoli says.  

NEXUS Project Inspires Interdisciplinary Collaboration

NEXUS scientist Dr. Mehdi Etezadi-Amoli’s research not only helps in the creation of renewable energy but also contributes to the U.S. Department of Energy’s vision of the future “smart” electric power infrastructure. The smart grid will facilitate the integration of solar power into the electric grid while providing a reliable energy supply. Tools to monitor and control microgrids are key to the success of the smart grid technology and Etezadi-Amoli is collaborating with Dr. Yahia Baghzouz of the University of Nevada Las Vegas (UNLV) to design a remote monitoring and control system for the microgrid at UNLV.

“This interdisciplinary collaboration between Dr. Etezadi-Amoli and Dr. Baghzouz has come about thanks to the NEXUS project” said Dr. Gayle Dana, Project Director of the NEXUS project. “We aim to create an environment that encourages collaboration between the disciplines in the quest to advance the efficiency of solar energy while minimizing its environmental impacts”.


Nexus Notes monthly publication
July 2017

NEXUS Notes is a monthly publication of the Solar Nexus Project, which is a five-year research project funded by the National Science Foundation’s Established Program to Stimulate Competitive Research “EPSCoR” (Cooperative Agreement #IIA-1301726) focusing on the nexus of (or linkage between) solar energy generation and Nevada’s limited water resources and fragile environment.

Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation.


If you would like to know more about the NEXUS project,
please contact, Dr. Gayle Dana


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