By Timothy Kelly
The Earth and Mineral Sciences Energy Institute, Penn State University. Photo: T. Kelly
Waste heat is the unused heat given to the surrounding environment (in the form of thermal energy) by a heat engine in a thermodynamic process in which it converts heat to useful work. Recovering and recycling waste heat has environmental, economic and efficiency benefits, like reducing use of fossil fuels.
A new battery developed by a group of Penn State researchers could have big implications on making the world more energy efficient, keeping electric prices down and the grid running smoothly.
Changing waste heat into electrical energy and generating power in new ways
Existing thermally regenerative ammonia batteries (TRABs) convert low-grade waste heat (at temperatures less than about 266 degrees Fahrenheit) into energy. The waste heat is used to remove ammonia from one of two battery solutions. This, in turn, creates chemical energy by generating concentrated ammonia and, then, dissolving the ammonia in the second of the two battery solutions recharges the battery. However, this existing process is either inefficient or costly, depending on the exact method.
“This research advances a new energy conversion concept that supports the goals of an energy transition: lowering CO2 emissions and diversifying our energy portfolio. These goals fit in with [Penn State’s] mission of being a global leader in energy research.”
To solve this, Derek Hall, assistant professor of energy engineering at the Department of Energy and Mineral Engineering, in the College of Earth and Mineral Sciences, and a team created a new battery with energy storage and power generating systems that are liquid, not solid. The researchers replaced “deposition-based reactions” with an aqueous copper chemistry, which had never been done before, until Hall and team set out to determine if it would work.
The good news? It does. The team’s next step is to optimize the battery’s design chemistry to determine if these batteries are truly economical and practical to use.
What’s the impact?
Copper is more abundant and less expensive than the rare earth metals currently used in U.S. grid-scale storage batteries, meaning this new development at Penn State could, ultimately, reduce energy storage costs.
In a Penn State news article, Bruce E. Logan, Evan Pugh Professor and Kappe Professor of Environmental Engineering, called thermally regenerative batteries “a carbon-neutral way to store and convert waste heat into electricity with potentially lower cost than solid-state devices."
Hall said, “Waste heat is abundant throughout the globe. If developed, TRABs can convert a portion of this untapped resource into a lot of useful energy…”
“This type of battery,” he added, “can supply energy when the sun isn't shining, and the wind isn't blowing. New energy sources like this are needed to keep electric prices down and the electricity grid operating smoothly.”
Put simply, these new batteries could make the world more energy efficient.
The Hosler building, home base for the Department of Energy and Mineral Engineering. Photo: T. Kelly
Hall continued, “This research advances a new energy conversion concept that supports the goals of an energy transition: lowering CO2 emissions and diversifying our energy portfolio. These goals fit in with [Penn State’s] mission of being a global leader in energy research.”
Don’t look for these innovative and practical these batteries for your home. They are expected to be the size of a shipping container, according to Hall, and will more likely be used in power utility and industrial-scale applications.