More than 3.5 million miles of rivers snake though countryside and cities alike in the United States.
Worldwide, half the population lives within a few miles of a river, while less than 10% live more than 10 miles away from one.
These statistics underlie the historical dependency humans have had on rivers, continuing to this day.
With so much access to flowing water, University of Virginia School of Engineering professor Hilary Bart-Smith recently wondered if it could be possible to convert river currents into electrical currents using her research in bio-inspired hydrofoils—also known as robotic fish fins—found on her lab’s famous Tunabot.
The system she envisions would allow for low-cost devices, with minimal environmental impact on ecosystems, to be placed in rivers to covert flowing water into energy. The devices would connect to local power grids, providing electricity to consumers. This new renewable energy device could be especially useful in areas where there is already limited access to electricity—like very rural communities located near rivers in Alaska or farming communities on the African Continent.
As climate change continues to affect weather, and by extension energy usage, the strain on aging power grids will continue to grow—as it has recently during the recent cold snap in Texas and other states where over a million people experienced power outages.
Over the next three years, Bart-Smith, professor of mechanical and aerospace engineering, will lead a multi-institutional team of researchers from UVA Engineering, Virginia Tech, Lehigh University and Sandia National Laboratories in the development of the bio-inspired, renewable energy device after receiving a $3.5 million grant from the U.S. Department of Energy's Advanced Research Projects Agency - Energy (ARPA-E).
“This is an idea that could potentially have a significant impact on low-cost, reliable energy production within areas of the country which are very sparsely populated but still need access to electricity,” Bart-Smith said.
Humans have long depended on rivers for food, both directly through fishing and through the development of grist mills that divert flow to power large grinding stones that crush wheat into flour, for example.
But that dependency on rivers took a huge leap forward on September 30, 1882, when the world’s first watts of water-powered energy were kicked out of a hydroelectric dam built on the Fox River in Appleton, Wisconsin. Electricity was achieved by controlling the outflow of water to power turbines that produced electricity. Edison’s lights lit up the night with this new form of renewable energy. However, the price for using dams for hydro power is high.
The Three Gorges Dam on the Yangtze River, the world’s largest hydroelectric dam that officially finished construction on July 4, 2012, has displaced as many as 3.67 million people and threatened even more with water-borne diseases, landslides and loss of farming income. Environmentally, more than 400 plant and animal species have been threatened. Similar impacts have been felt in the United States. Thousands of acres of land have been lost to areas above dams, and huge changes are unavoidable downstream as the water that once flowed freely slows to a trickle. Then there’s the dilemma of what to do with a dam once it has outlived its structural life.
The bio-inspired device that Bart-Smith and her team of researchers are developing would add to the current renewable energy mix of solar and wind — augmenting some of the inherent challenges facing those sources, like cloudy or windless days.
The team is designing a device that consists of a pair of hydrofoils that open and close with the flow of the water, in the way a scuba flipper moves under water.
The oscillating motion of the foils powers a mechanical motion rectifier, a major component of the device, designed and patented by Lei Zuo, Virginia Tech Robert E. Hord, Jr. Professor and member of Bart-Smith’s team, that coverts the bidirectional oscillating motion to a unidirectional rotary motion in a gear box that can churn a generator and convert the flowing river energy to electricity. Zuo first built his mechanical motion rectifier to convert bobbing buoys in a marine environment into electrical energy.
The entire device will be anchored to the riverbed or will float in the river or ocean, and will be designed to have a small footprint with the goal of limiting any changes to the riverbed and the marine environment.
Sensors on the various parts of the device will calculate river flow, water height and possibly even turbulence caused by excessive rain, and then will use artificial intelligence to make changes to the way the device operates in real time in order to maintain maximum energy grabbing efficiency. Giorgio Bacelli, senior research engineer at Sandia National Laboratories, will oversee the design of these real-time control systems.
Bart-Smith’s former doctoral student Keith Moored, who earned both his bachelor’s and Ph.D. degrees at UVA Engineering, is now an associate professor in the Department of Mechanical Engineering and Mechanics at Lehigh University, will focus on the flow dynamics of the hydrofoils. He worked with Bart-Smith on the groundbreaking development of a bio-inspired, robotic manta ray during his graduate studies at UVA Engineering.
“Energy independence is very critical, especially in times when there's going to be potentially energy scarcity with climate change happening and economies changing,” Moored said. “We also have to think beyond just solely the energy production in and of itself, and think more holistically to what's the impact that this energy production will have on the local environment.”
Moored will work closely with Bart-Smith, Eric Loth, Rolls-Royce Commonwealth Professor and chair of the UVA Department of Mechanical and Aerospace Engineering, and other teammates on the project to run numerical simulations that can help the group optimize the various hydrodynamic parameters inherent in the design of a complex system like this—with the goal of creating a device that maximizes efficiency in an ecofriendly way.
Bart-Smith said the team is aiming to have a one-third-sized prototype ready for testing in the Rivanna River in about two years. The engineering challenges are daunting—like determining how long a device of this nature will hold up in an underwater environment.
“On an individual component level, we all feel pretty confident in our respective technologies and physics that we're proposing,” Moored said. “But I think the challenge is really going to come into play when we start to integrate these individual components and physics in a way that there may be trade-offs between what's best for each individual technology.”
If the team is able to realize the potential for the device, they envision developing an industry advisory board and working with business students to develop a commercialization plan. They plan to incorporate the feedback from those partners into a prototype refined for real-world conditions, proving the device is viable both as a research concept and a commercial product.
“This isn't just an academic, intellectual idea with many interesting scientific questions. Successful implementation of our ideas in the commercial market has the potential to create energy for remote communities,” Bart-Smith said. “We want people using our technology and benefiting from it.”
UVA Engineering is Leading a Three-year, $3.5 Million, Multi-institution Study to Build an Eco-friendly Device that Will Convert River Currents to Electrical Currents
More than 3.5 million miles of rivers snake though countryside and cities alike in the United States. Worldwide, half the population lives within a few miles of a river, while less than 10% live more...