University of Wollongong researchers are among an international team who have developed more efficient thermocells that might eventually be used for generating electrical energy from heat discarded by chemical plants, automobiles and solar cell farms.
A study published in the American Chemical Society’s journal Nano Letters reveals that thermo-electrochemical cells using relatively inexpensive carbon multiwalled nanotube* electrodes can harvest low-grade thermal energy (temperature below 130 degrees Celsius). [*Nanotubes are cylindrical carbon molecules with novel properties that make them potentially useful in many applications in nanotechnology, electronics, optics and other fields of materials science].
The journal reported that UOW scientists from the Intelligent Polymer Research Institute (IPRI) have been collaborating on the project with researchers from the US and India.
One of the demonstrated thermal cells looks just like a button cell battery. However, over its lifetime this thermocell can continuously generate electricity, instead of running down like a battery. Other demonstrated thermal cells are electrolyte-filled, textile-separated nanotube sheets that can be wrapped around pipes carrying hot water that exits a manufacturing or electrical power plant. The temperature difference between the pipe and surroundings produces an electrochemical voltage and corresponding electrical energy generation.
Researchers found that a threefold increase in energy conversion efficiency resulted from replacing conventional electrodes in thermocells with the carbon nanotubes electrodes.
Professor Ray Baughman, the Robert A. Welch Chair in Chemistry at the University of Texas and Director of the Alan G. MacDiarmid NanoTech Institute, said Texas has long been the Energy State because it has oil and gas in the ground and Texans have invented key technologies for bringing them to the surface.
“But being the Energy State in the future must increasingly include discovering new means for extracting all forms of energy. Harvesting waste thermal energy is just one direction our NanoTech Institute has taken with our international team of researchers to help provide an energy enabled future for Texas and the world,” Professor Baughman said.
IPRI Director, Professor Gordon Wallace, said the team took advantage of the exceptional electronic, mechanical, thermal, and chemical properties of carbon nanotubes.
Professor Wallace said that efficiently harvesting the energy currently wasted in industrial plants or along pipelines could create local sources of clean energy that could in turn be used to lower costs and an organisation’s energy footprint.
On a smaller scale, button cell size thermocells could be used to power sensors or electronic circuits, he said.