Feb. 16, 2001 Gainesville, FL (Feb. 12, 2001) --- If you've ever lost a computer file when the power died, you know California isn't the only state with an electricity problem.
A device taking shape in a University of Florida laboratory could lead to more reliable electricity, shoring up the nation's aging power grid at a time when deregulation and the other forces behind California's blackouts are steadily creeping into other states.
In an article that appears today in "Applied Physics Letters," a leading physics journal, a team led by UF engineering researchers report building a device, known as a rectifier, that comes closer than ever before to meeting the requirements for a new kind of highly reliable electronic switch. Made out of a material called gallium nitride, the rectifier can withstand 10 kilovolts, a world record for the material and not far from the minimum of 13.8 kilovolts seen as required for the switch to become a possibility for residential power lines.
"We're not there yet, but we're within sight of our goal," said Stephen Pearton, a professor of materials science and engineering. "In another year or two, we should be able to get to the point where these switches are feasible."
Although it can be much higher, 13.8 kilovolts is the minimum amount of power transferred on residential lines. Today, that power is moved around using mechanical switches. When you get up in the morning and turn on the lights and coffee maker, these switches close, allowing more electricity to flow from the neighborhood line into your house. Other mechanical switches route power to the neighborhood and on to the power plant.
Mechanical switches have a number of problems. One is that as they open and close, they send electrical spikes down the line. While the spikes don't necessarily kick off the power, they may shut down computers and other electronics. That's why your computer sometimes shuts off but the lights remain on.
To avoid such spikes, or more serious outages, the power grid has to be operated below its rated capacity, Pearton said. That means it actually carries less electricity than it is capable of, a problem for power-starved areas such as California, he said.
Because they open and close nearly instantaneously, electronic or "solid state" switches would eliminate the spikes while allowing the grid to run at a higher power level.
"The utilities could run the systems more efficiently, so they could get closer to a blackout situation before it would become a disaster," Pearton said.
The switches wouldn't solve California's problems, but they would make it easier to get electricity to the state from elsewhere during emergencies.
"These switches could help with the blackouts," said Ben Damsky, an official with the Electric Power Research Institute, or EPRI, in Palo Alto, Calif. "By added use of such devices, it would be possible to send more power over longer distances and make even more remote generators accessible to California's lines."
The switches would also enable utilities to switch customers from a failing power source to a working source faster than possible today, leading to briefer outages, Damsky said. . Electronic switches exist now, but the material used in them, silicon, heats up, requiring a cooling system. That makes the switches expensive and impractical, Pearton said.
Besides making blackouts easier to combat, the switches could help ensure seamless, uninterrupted electricity, Damsky said. Such electricity is of vital importance to microchip plants and other industries that face millions of dollars in production losses from even brief outages. It is expected to be sold for a premium price in future electricity markets.
"We're looking to the kind of devices that Dr. Pearton and his colleagues are working on to make something ... commercially viable for a premium service," Damsky said.
EPRI and the Defense Advanced Research Projects Agency have funded the UF research with a three-year, $2.5 million grant.
The Microelectronics Center of North Carolina is a partner with UF in the research. Other researchers on the project include Fan Ren, a professor of chemical engineering and co-principal investigator on the project with Pearton; A.P. Zhang, J.W. Johnson and K.P. Lee, graduate students in the UF departments of chemistry and materials science and engineering; J. Han of Sandia National Laboratories; A.Y. Polyakov, N.B. Smirnov and A.V. Govorkov of the Institute of Rare Metals in Russia; and J.M. Redwing of the department of materials science engineering at Pennsylvania State University.
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