An efficient method to harvest low-grade waste heat as electricity may be possible using reversible ammonia batteries, according to Penn State engineers.
"The use of waste heat for power production would allow additional electricity generation without any added consumption of fossil fuels," said Bruce E. Logan, Evan Pugh Professor and Kappe Professor of Environmental Engineering. "Thermally regenerative batteries are a carbon-neutral way to store and convert waste heat into electricity with potentially lower cost than solid-state devices."
Low-grade waste heat is an artifact of many energy-generating methods. In automobiles, waste heat generated in winter is diverted to run the vehicle heating system, but in the summer, that same waste heat must be dissipated to the environment. Coal, nuclear and other power plants require high heat to produce electricity, but after producing electricity the excess waste heat is routed to cooling towers to dissipate. Many industrial sites, geothermal sources or solar generating plants also create low-grade heat that is wasted.