Superconductivity is not yet a household word. But it`s a hot new area of scientific breakthroughs that eventually may affect every household in the land.
These breakthroughs, according to excited scientists, could revolutionize the way this country generates, sends and stores electric energy.
The greater efficiencies that superconductivity allows could save consumers billions of dollars a year from lower utility costs and reduce the need for imported oil to produce electricity.
Ultimately, the new technology could let utilities place power plants farther from urban customers.
Researchers say significant advances are coming almost by the week, with commercial applications looming in the future. Some of the advances have been front-page news, but the impact on the energy industry is just becoming apparent.
Superconductive materials can conduct electricity without resistance, making them the most efficient conductors possible because there`s no energy loss. But, until now, there has been a big drawback: They work only at such extremely low temperatures that their use has been prohibitively expensive and all but impossible.
Recent advances, however, have dramatically raised the temperatures at which materials are superconductive from minus 459 degrees Fahrenheit to minus 270 degrees. Some scientists even foresee superconductivity at room temperature.
”If they have that breakthrough, it would rewrite the books on electric generation and transmission,” said Ed Steeve, a research engineer at Commonwealth Edison Co. ”For electricity, it would be like walking on the moon.”
Utility engineers stress that it probably will take 10 years of continued successful research and the establishment of new manufacturing facilities before superconductive material is used by utilities.
Also, the heavy investment in existing generators and transmission lines suggests that superconductivity will not bring about an overnight scrapping of older equipment; the new technology will probably be introduced gradually.
”At this point, we`re very early in the game,” said Mario Rabinowitz, senior scientist of advanced research projects at the Electric Power Research Institute, Palo Alto, Calif., the utility industry`s research and development laboratory.
”But if we take an optimistic point of view, the momentous achievements have the potential of leading to practical developments that are likely to dramatically change if not revolutionize utilities.”
The scientists` excitement began at the start of the year.
Until then, it was believed that superconductivity could be achieved at temperatures only a few degrees above absolute zero on the Kelvin scale, or 459 degrees below zero Fahrenheit.
To lower temperatures that much, liquid helium had to be used. Liquid helium is expensive and hard to work with and the cooling systems are complex, making superconductivity impractical for all but a few purposes.
By using different compounds, however, physicists at the University of Houston created a ceramic material that they announced in January was superconductive at minus 390 degrees Fahrenheit. That was the first breakthrough.
Since then, thousands of scientists worldwide have joined the research. In March, physicists at the U.S. Energy Department`s lab in Los Alamos, N.M. achieved superconductivity at minus 270 degrees Fahrenheit, permitting them to use cheaper, abundant liquid nitrogen as a coolant.
Late last month, two physicists at Wayne State University, Detroit, announced findings indicating that superconductivity could be achieved at 27 degrees below zero, a temperature easily reached by a conventional freezer.
”It blows the mind and expands the imagination,” said Arthur Freeman, chief physicist of a team at Northwestern University`s Materials Research Center.
Scientists say superconductivity probably will be used first in computers and electronics in which less of the ceramic material would be needed. Some researchers dream of levitating trains speeding above superconductor electromagnetic rails.
But physicists and engineers say superconductivity could be applied later by utilities, most likely in transmitting large blocks of power and storing electricity in electromagnetic rings.
Electricity is transmitted between generators and distribution networks through overhead lines and, to a lesser extent, in underground cables in cities. The lines typically are made of aluminum alloys.
But as electrons flow through the wires, resistance is encountered, causing some of the electricity to be transformed into heat. The Power Research Institute figures that 10 percent of transmitted electricity is lost to resistance.
Translated into dollars, the loss is huge. Virgil Rose, vice president of electric operations at Pacific Gas & Electric Co., San Francisco, the nation`s largest utility, said resistance saps $200 million of electricity each year from PG&E`s transmissions.
If superconductive materials were used, no energy would be lost. This is a potential savings of $2 billion to $4 billion a year nationally, according to research institute estimates.
Engineers say, however, that there are several reasons superconductive lines will not quickly replace the more than 600,000 miles of metal transmission cables running overhead across the country.
First, the recently discovered superconductive ceramics are brittle and do not have the tensile strength to be strung overhead.
(Physicists say the brittleness of current compounds also would make them difficult to use in electric generators in which fine, hair-like wires are needed and centrifugal force could pull the filaments apart.)
Next, to be superconductive, the material must be cooled. This means running the ceramic cable in an envelope or tube of liquid nitrogen. That not only adds weight but also requires constantly monitored refrigeration machines along the line.
Finally, though utilities could reduce energy losses by up to 10 percent, the investment in existing transmission lines and the cost of stringing new lines outweigh the savings, utility managers say.
For underground uses, however, superconductive materials look much more appealing and could solve a problem that limits the capacity of beneath-the-street electric lines.
Because of the heat given off from resistance, Rose said, utilities must restrict the energy flowing through the wires to prevent fires. By eliminating heat, superconductivity would increase the capacity of the underground lines in addition to saving power.
The brittleness of the ceramics and the weight of the liquid-nitrogen-coole d envelope also would pose few difficulties underground.
Engineers concede that the enormous cost of laying underground lines
–generally 10 times as expensive as erecting towers–would make it uneconomical to run superconductive cables long distances.
But Rose and others predict that utilities could begin putting in underground superconductive cables in urban areas in 10 years or less.
Meanwhile, scientists are investigating new compounds that combine ceramics with metals. They also are looking into sandwiching the material between layers of metal, such as copper, and making superconductive tapes.
Researchers hope new discoveries can overcome the weaknesses of superconductive materials. Some predict that shortly after the turn of the century utilities could begin stringing superconductor lines overhead as primary transmission lines need replacement or service is expanded.
Scientists say the superconductivity breakthroughs also could make efficient storage of electricity possible, and utility managers say that could save billions of dollars through more efficiently operated power generators.
Little power is stored now. A few utilities are experimenting with huge batteries, and others effectively store power by pumping water up to a reservoir at night then letting it flow back down through turbines to generate electricity the next day.
Most utilities, however, increase or decrease their generator`s output to match demand. Engineers say these power swings are wasteful.
Nuclear facilities operate most efficiently at a constant output. Therefore, engineers say, oil-fired units are called upon to boost output in peak-demand periods, such as a record-breaking hot day in August.
But if the energy could be stored, the power generators could run at the same level 24 hours a day. The excess at night could be stored and tapped during the day when demand peaks.
Physicists at the applied superconductivity research center at the University of Wisconsin`s engineering college at Madison have developed such a system, which is called superconducting magnetic energy storage.
And the Fermi National Accelerator Laboratory, near west suburban Batavia, uses the technology to power its atom smashers.
The superconducting magnets–huge rings buried in a trench–rely on liquid helium for cooling, however, making them too expensive for use by utilities.
But researchers say that if liquid nitrogen is used, superconducting magnetic energy storage could become economical.
Roger Poeppel, manager of the ceramics section of the materials and components technology division at Argonne National Laboratory, near southwest suburban Lemont, compares the superconductive magnets to an automobile coil that holds a charge before releasing it to the spark plugs.
But, unlike the coil, which can hold a charge for only a split second, a superconductive magnetic ring, which has no resistance if cooled,
theoretically could hold energy forever.
Poeppel said scientists have designed superconductive magnets that could store five hours of output from a typical nuclear power plant. That`s enough to meet the demand of a large city for several hours.
The magnetic ring would be a mile in diameter, however, ”so it`s not clear to me just how practical that is,” he said.
But researchers and engineers say the magnets could be placed far from built-up areas and the stored electricity efficiently transmitted over superconductive lines.
Some people take it a step further. Superconductivity also could allow the construction of nuclear power plants or generators fired by ”clean coal” far from metropolitan customers.
Engineers caution, however, that the changes from superconductivity probably will not be sweeping or immediate.
”In theory, superconductivity is now possible, but the question is how are the dollars going to shake out,” said David Fiorelli, senior engineer at TU Electric Co., which serves north-central Texas, including Dallas-Ft. Worth. ”We see this as still years down the road before we see any applications,” he said.
But, Northwestern`s Freeman said: ”Unlike previous technological breakthroughs, this one is being worked on by literally thousands of people at almost every university, industry and government lab in the U.S., Japan, Western Europe and China. The developments are therefore coming at an enormously rapid pace.”
