CHICAGO (AP) _ The discovery of new higher-temperature superconducting materials could give the nation the equivalent of up to 15 percent additional electrical generating capacity by making it feasible to store energy indefinitely, a study estimates.

The new superconductors, materials that conduct electricity with no loss of energy from resistance, also could mean dramatically cheaper costs of running electrical generators and large electrical motors, the study found.

The study found that the nation's electrical generating capacity could be boosted if the new technology can be made into practical, usable wire.

''The first thought that is voiced about superconductivity is that because it's more efficient, it will save energy and cost less,'' said Alan Wolsky, who directed the study for Argonne National Laboratory.

Argonne was designated the national center to develop new superconductivity technology.

One of the most promising areas envisioned, Wolsky said, is in the area of storing electricity.

The scientists surveyed estimated that these superconductors could be used to create less-expensive magnetic energy storage systems. By storing electricity for periods of high demand, such as at midday or early evening, the United States could gain additional generating capacity of up to 15 percent, the study said.

The study found that money also could be saved in the costs of building new electrical transmission equipment and by increasing the reliability and efficiency of existing equipment, Wolsky said.

But he stressed, ''There is a long way to go and much research to be done before turning the discoveries that have been made in the last year into practical wire.''

If the process can be controlled and the right materials developed, scientists believe superconductivity offers the promise of cheaper electrical power, faster and more efficient electronics and powerful magnets with a range of uses, including levitating high-speed trains.

Late last year, scientists at Argonne built what they said was the world's first electrical motor based on newly discovered superconducting ceramics.

In their study, researchers surveyed experts at five of the nation's leading research institutions to get their best estimates on how much money the new technology could save, said Wolsky, director of technology and evaluation in Argonne's energy and environmental systems division.

Until recently, superconductivity had been known in certain materials, but only when they were cooled to nearly absolute zero - 459.7 degrees below zero on the Fahrenheit scale - a process so expensive it made the materials impractical.

But in the past year, scientists have produced materials in the laboratory that become superconductors at much higher temperatures - creating new interest in the field because it wouldn't cost so much money to cool them.

In the Argonne survey, the scientists were asked to estimate the cost savings from recently discovered copper-oxide ceramics that lose resistance to electrical current when cooled with liquid nitrogen to minus 321 degrees Fahrenheit.

They estimated that this superconductor - if turned into usable wire - could cut the costs of running large electrical generators by up to 60 percent by improving their efficiency to 99.7 percent and reducing energy losses by 80 percent.

Conventional generators operate at 98.5 percent efficiency, the study said.

High-temperature superconductors also could cut the cost of running large electrical motors of 1,000 horsepower or more by up to 25 percent, the study said. The savings would come from increasing their efficiency to about 99 percent from the current range of 75 percent to 95 percent.

The Argonne survey also estimated that the superconducting materials could make it less expensive to build high-speed magnetically levitated trains by enabling the construction of stronger, lighter magnets.

Argonne, west of Chicago in Argonne, is run for the U.S. Department of Energy by the University of Chicago.