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ARPA-E Funded “Water Windmills” Make Waves in Energy Sector

In the US, hydroelectric power is the oldest form of renewable energy and accounts for 6.6 percent of the nation’s energy production. However, the hydropower dams in the US have aging infrastructure and are on average over 80 years old.

Dams are also the cause of environmental degradation of waterways and can even contribute to greenhouse gas emissions from the methane released from submerged vegetation. Yet, harnessing hydroelectric power in environmentally sustainable ways remains a critical part of the effort to decarbonize the electric grid.

Two professors at UT are contributing research to The Submarine Hydrokinetic And Riverine Kilo-megawatt Systems (SHARKS) program of the US Department of Energy’s Advanced Research Projects Agency-Energy (ARPA-E) project, which aims to speed up the process of making hydrokinetic turbine designs for tidal and riverine currents more economically viable.

The organization has granted eleven teams a total of $35 million to work to reduce the levelized cost of energy by incorporating experts in hydrodynamics, structural dynamics, control systems, power electronics, grid connections, and performance optimization.

Orlando Rios, assistant professor in the Department of Materials Science and Engineering (MSE), and David Harper, professor with the Center for Renewable Carbon (CRC) at the UT Institute of Agriculture, are key members of the Emrgy, Inc, team, which received $3.6 million through the program. Emrgy is an Atlanta-based startup that builds small, modular, flexible underwater turbines that can be scaled at high quantities and placed in existing waterways without the need for any modification of the existing infrastructure.

With distributed hydroelectric, power companies and manufacturers will be able to harvest the kinetic energy, or the movement of the water, instead of the potential energy that gets harvested when a river gets dammed. Harvesting kinetic energy requires far less infrastructure, but to make distributed products, the cost of manufacturing must decrease. The other important factor is to make sure the materials are corrosion-resistant, especially because they are aqueous. This is why Emrgy is partnering with UT’s MSE and CRC.

“We are thrilled to partner with UT’s MSE and CRC to advance Emrgy’s technical innovations, particularly in the material advancements related to long-life, high performance underwater systems,” said Emily Morris, Emrgy’s Founder and CEO.

Current riverine hydroelectric design by Emrgy

Current riverine hydroelectric design by Emrgy.

Together, Harper and Rios are trying to design the sustainable materials that will go into Emrgy’s kinetic turbine systems.

“When one hears of renewable energy solutions, it’s not uncommon for such solutions to be reliant on critical materials or environmentally costly processing,” said MSE and CRC graduate student Cotton Pekol, a research assistant for this project. “For this reason, we are very excited to participate in developing viable renewable energy solutions that are environmentally conscious each step of the way.”

Emrgy already has blades designed for riverine water systems, but the funding from the ARPA-E project will be focused on harvesting the energy from the rising and falling tides of brackish water. Their research collaboration is currently focused on designing materials that will adapt to the water height with a telescoping design, where the blades can get longer or shorter based on the tidal pool.

Rios is focused on creating an aluminum alloy from recycled feedstock, where the main alloying element is a waste product of a Rare Earth Mines mine.

“The alloys we are working on don’t require heat treatment so they are more energy efficient,” he said. “When you heat treat anything with a high aspect ratio–like a blade–it gets distorted, and then you have to straighten it, which costs money.”

Harper’s expertise is in lignin-based composites. Lignins are organic polymers that are important in the formation of nearly 25 percent of woody plant cell walls. Large amounts of lignin are produced as a byproduct of pulp and paper manufacturing and burned to produce energy.

Harper says that lignin is an important energy source for the wood products industry in North America. However, not all of the lignin is burned, and fuel represents an important, yet low-value use.

“We aim to take part of this abundant resource and produce more value for the forest products industry,” he said. “We are designing lignin-based and recycled carbon fiber composites to make a low-cost and more sustainable material.”

SHARKS is expected to span three years with $38M in funded projects.

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