A new technology being developed at the Department of Energy’s Oak Ridge National Laboratory could see billions in savings each year through the transformation of waste into electricity.
The high-efficiency thermal waste heat energy converter actively cools electronic devices, photovoltaic cells, computers and large waste heat-producing systems while generating electricity.
According to Scott Hunter, leader of the development team, the potential for energy savings is enormous.
"In the United States, more than 50 percent of the energy generated annually from all sources is lost as waste heat," Hunter says, "so this actually presents us with a great opportunity to save industry money through increased process efficiencies and reduced fuel costs while reducing greenhouse gas emissions."
Hunter's technology uses cantilever structures that are about 1 millimeter square in size. About 1,000 of these energy converters can be attached to a 1-inch square surface such as a computer chip, concentrated photovoltaic cell or other devices that generate heat.
Although the amount of electricity each device can generate is small – 1 to 10 milliwatts per device – many arrays of these devices can be used to generate sizable amounts of electricity that can power remote sensor systems or assist in the active cooling of the heat generating device, reducing cooling demands.
The device is based on an energy harvesting system that features a micro-electro-mechanical (MES) pyroelectric capacitor structure that when heated and cooled causes current to flow in alternate directions, which can be used to generate electricity.
In this configuration, cantilevers are attached to an anchor that is affixed to a waste heat generator substrate. As this substrate becomes hot, the cantilever also heats and bends because of the bi-material effect, similar in principle to the bimetal switch used in room and oven thermostats.
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