More than Half of U.S. Energy Goes to Waste – But Not for Long

May 17th, 2011 by Tina Casey

Researchers at the Oak Ridge National Laboratory estimate that the U.S. loses more than half the energy it generates. That doesn’t include heating and cooling loss from buildings, just energy that vanishes into the atmosphere from machines, industrial processes and electronic equipment. In order to reclaim and recycle some of this energy, the researchers are developing a highly efficient thermal waste heat energy converter. The new device would do double duty. It would cool down electronic equipment including photovoltaic cells in order to keep them functioning efficiently, while capturing the waste heat to generate electricity.

ORNLS’s New Thermal Energy Converter

The team is developing a device that is only about one millimeter square, and each one delivers only 10 milliwatts – at best. That sounds like a drop in the bucket but it’s nothing to sneeze at when you attach hundreds of these devices to, say, a tiny object such as a computer chip. The principle is based on pyroelectricity, which refers to the ability of some materials to produce a temporary charge when they are heated or cooled. The catch has been getting pyroelectric devices to operate at a high enough level of efficiency to make them cost-effective. The ORNL team came up with a relatively inexpensive cantilevered structure that promises to do just that (a cantilever, broadly speaking, is a structural beam supported only at one end).

Other Ways to Harvest Waste Energy from Machines

ORNL has gone the high tech road, which is years away from commercial development. However, more conventional means are already available. One example is an a new energy harvesting system up at Thule Air Force Base in the Arctic Circle, which captures exhaust heat from the facility’s generators. You can also harvest kinetic energy from a machine’s vibrations, or from the braking systems in vehicles, cranes, trains and other stop-and-go equipment.

Waste Heat as a Low Risk Energy Resource

Considering the amount of energy at stake, widespread use of thermal energy converters and other machine-based energy harvesting equipment is akin to discovering a new resource – one that can be safely harvested where humankind has already developed the natural environment, with virtually no additional disruption. That’s a stunning contrast to high risk energy harvesting such as hydrofracking, deep sea oil drilling and mountaintop coal removal.

Harvesting Energy from Developed Lands

Machines and equipment are one area ripe for low-risk energy harvesting, and there are others. For example, the Nature Conservancy has pointed out that wind farms can disrupt habitats for endangered and at-risk species, but the solution is simple: there is ample space in the U.S. to exploit wind resources on developed lands, where habitat is not an issue. Similarly, the U.S. EPA has developed a program to build wind turbines and solar installations on brownfields and other classifiied sites that can’t be used for much else aside from further development.

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Image: Machine by zigazou76 on flickr.com









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