Building a perpetual motion machine remains as impossible as ever, but scientists are close to making something almost as good-a low-friction flywheel that loses energy at the rate of only 2 percent a day.
Superflywheels may be among the first high-profile applications of ”high temperature” superconductivity, a technology that has been making significant, but relatively quiet, laboratory research advances and promises to become a major commercial technology by the end of the decade.
Five years ago, physicists discovered new materials that lose their resistance to carrying electrical current at temperatures much higher than the super-cold temperatures previously believed necessary. Their findings rocked the scientific world and spurred research in a worldwide race for new discoveries.
Every few weeks, or so it seemed, scientists held press conferences to announce a new mixture of materials or new ways of processing known mixtures that achieved superconductivity at higher and higher temperatures.
Some predicted that finding a material that carried electricity without resistance at room temperatures was likely, and physics seminars took on a carnival atmosphere. President Reagan addressed a superconductor technology gathering in Washington to urge on American scientists competing with foreign reseachers, especially the Japanese.
The hoopla subsided long ago, and it`s been years since anyone produced a material that superconducts at a new record high temperature. But researchers have continued to make solid progress, and the promise of a new era of superconducting products gets closer to fulfillment with each passing month.
Technology to make superconducting flywheels, motors and even magnetically levitated vehicles should be available in research labs within a few years, researchers promise. Commercial applications will take longer to develop and their success will, of course, depend upon market factors.
But it seems likely that superconducting products will be welcome in some commercial niches, perhaps within five years or less. Americans are at least even with, and perhaps ahead of, Japan in bringing new technology to market.
An ultralow-friction superflywheel offers several product development possibilities.
Flywheels are wheels with permanent magnets attached that use electricity flowing through a coil to start spinning at high speed. The wheel continues to spin after the electricity is turned off, storing the energy until the process is reversed and electricity flows out of the system.
Flywheels offer several advantages over batteries as energy storage devices. They may ”charge up” with energy in five minutes of electrical input instead of hours or overnight as batteries usually require, and they don`t wear out after several cycles of charge and discharge as batteries do.
The flywheel`s chief disadvantage is loss of energy to friction as it spins. A superflywheel suspended in space by a superconductor`s magnetic force and enclosed in a vacuum could spin on and on without much energy loss to friction or air drag.
The first big step toward superflywheels already has been taken and tested by researchers at United Technologies Research Center and Argonne National Laboratory who have built a superconducting bearing system, which would be the crucial component to suspend a flywheel so that it doesn`t touch anything.
Flywheel technology already is well advanced, with new strong, lightweight materials like Kevlar or carbon composites tested extensively, said John R. Hull, Argonne`s materials superconductivity applications manager. And the high-temperature superconductors already known are adequate to suspend a flywheel in space.
The superconductors must be kept at about minus 321 degrees Fahrenheit, the point at which nitrogen becomes a liquid. But that isn`t a problem, said Hull. Refrigeration units are readily available to achieve such temperatures, he said.
Early results indicate it should be possible to make a flywheel with perhaps 1,000 times less friction than offered by conventional technology, Hull said, ”and we can probably do much better. We`ve just scratched the surface.”
While loss of resistance to flow of electricity is the primary way superconductors are defined in the popular mind, the materials have other properties related to the amount of current they can carry and the magnitude of magnetic fields they can sustain.
Expanding these properties has been the goal of scientists in recent years, and their continued success is about to yield fruit, such as the superflywheel. And industrial people are getting very interested, said Bob Weinberger, a research scientist at United Technologies Research Center in East Hartford, Conn.
”When these things were first discovered, they were just a scientific curiosity,” said Weinberger. ”You`d see a magnet suspended above a superconductor and say, `That`s cute, come back when you can do a 200-pound turbine shaft.` Well, now they`re getting into the range where you can start to consider practical applications.”
At the least, Weinberger said, superconductors will find practical applications in niches where low-friction-loss bearings are a must. As advances are made in processing superconducting materials, more and more applications will become apparent, he said.
Argonne`s Hull said the national lab has been charged by the federal government, which funds its research, to commercialize superconducting technology as quickly as possible, working with American companies to do so.
”We`re taking that mission very seriously,” said Hull.
Argonne has been in the forefront of research to make superconducting wires that can carry significant electrical current and sustain substantial magnetic fields.
Roger Poeppel, Argonne ceramics section manager, said he and colleagues have found the right chemical and mechanical composition for superconducting material to maximize its commercial potential. They are experimenting with processing techniques to achieve the desired composition properties consistently.
Poeppel said his 30-member team-there are about 100 people at Argonne working on one aspect or another ofsuperconductivity-is probably about two years away the ability to make superconducting wire reliably in sufficient quantities to wrap a coil for a motor.
Superconducting motors probably will be available for sale in four or five years, Poeppel predicted. The advantage of such motors over conventional ones is that they would be only one-third as large and would use less electricity to operate, but would provide comparable power.
”The biggest advantage will be in mobile applications where motor weight and size is important,” said Poeppel. ”Ships will probably be the first to use these motors.”
Using superconducting wires to transmit electricity may never be a practical alternative to regular overhead copper wires, Poeppel said, because the need to cool superconductors adds cost and bulk. But superconductors may well be used as transmission lines in underground conduits common in densely populated urban areas like Chicago`s Loop.
In such locations, he said, even enclosing superconducting wires in insulated tubes may be a cheaper alternative to copper wiring, especially in areas where existing conduits are almost filled, because the superconductors carry more current while using less space and producing no heat.
