New Energy Harvesters Reportedly Transform Waste Into Electricity

ORNL Logo Every year billions of dollars are spent in converting waste heat from industrial processes into electricity. On that note, ORNL scientists have now crafted a high-efficiency thermal waste heat energy converter that actively cools electronic devices, photovoltaic cells, computers and large waste heat-producing systems while generating electricity. This converter can seemingly save industry money through increased process efficiencies and reduced fuel costs while diminishing greenhouse gas emissions.

This technology was previously built to cool high-performance computer chips and thereby helping to solve an enormous problem facing manufacturers of petaflop-scale computers. These mega machines are believed to produce massive amounts of heat that must be removed, and the more efficient the process the better. The newly introduced energy converter apparently employs cantilever structures that are about 1 millimeter square in size. Approximately 1,000 of these energy converters can be supposedly attached to a 1-inch square surface such as a computer chip, concentrated photovoltaic cell or other devices that generate heat.

“The tip of the hot cantilever comes into contact with a cold surface, the heat sink, where it rapidly loses its heat, causing the cantilever to move back and make contact with the hot surface,” Scott Hunter, said. “The cantilever then cools and cycles back to the cold heat sink. “The cantilever continues to oscillate between the heat source and heat sink as long as the temperature difference is maintained between the hot and cold surfaces.”

Even though the amount of electricity each device can generate is small, many arrays of these devices appear beneficial in generating sizable amounts of electricity. This in turn may power remote sensor systems or assist in the active cooling of the heat generating device, reducing cooling demands. The fast rate of exchange in the temperature across the pyroelectric material seems to be the key to the energy conversion efficiency and high electrical power generation. The device is purportedly based on an energy harvesting system that features a micro-electro-mechanical, or MEMS, pyroelectric capacitor structure. This structure when heated and cooled presumably leads to current flow in alternate directions.

The research was funded by the Laboratory Directed Research and Development program.

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