Superconductivity is the ability of certain materials to conduct electrical current with no resistance and extremely low losses. This ability to carry large amounts of current can be applied to electric power devices such as motors and generators, and to electricity transmission in power lines.
Transmission lines that carry power without resistance, medical diagnostic tools that eliminate the need for surgery, "levitating" trains that speed along the tracks—these are not visions of the future, but examples of what superconductors are doing today.
Superconductors conduct electricity without losing energy to electrical resistance, as most conductors do. Certain materials become superconductors when they are cooled to very low temperatures. Low-temperature superconductors exhibit superconductivity at temperatures near 0 Kelvin (K) (or -273o Celsius [C]). Recently discovered high-temperature superconductors (HTS) can function at temperatures as high as 140 K (-133oC). This is an exciting discovery because these high-temperature superconductors can be cooled more economically and efficiently than can low-temperature superconductors.
Superconductors also repel surrounding magnetic fields. This phenomenon is demonstrated when we levitate a magnet above a cooled superconductor, and it is the force at work in Japan's famous Maglev train.
Superconductors help us use energy more efficiently and reduce the cost of electricity production, storage, transmission, and use, and the costs of transportation and medical equipment. Some current uses, and some that hold the most promise for the near future, are these:
Power transmission cables that carry current without energy losses will increase the capacity of the transmission system, saving money, space, and energy. Prototype power transmission cables have been developed and are being tested.
Motors made with superconducting wire will be smaller and more efficient. A 1,000-horsepower motor has been constructed and is undergoing testing by an SPI team led by Rockwell Automation/Reliance Electric Company.
Generators will use superconducting wire in place of iron magnets, making them smaller and lighter. New generators also may get more power from less fuel. An SPI team led by General Electric has developed a design for a 100-megavolt-ampere generator.
Current collectibles (i.e., fault-current limiters) help utilities deliver reliable power to their customers. HTS fault-current limiters detect abnormally high current in the utility grid (caused by lightning strikes or downed utility poles, for example). They then reduce the fault current so the system equipment can handle it.
Cellular phone base stations will use HTS filters. Some people predict that this will be one of the most significant early markets for HTS.
Magnetic resonance imaging (MRI) machines enhance medical diagnostics by imaging internal organs—often eliminating the need for invasive surgeries. MRIs, which currently are made with low-temperature superconductors, will be smaller and less expensive when made with HTS.
Maglev trains seem to float on air as a result of using superconducting magnets. These trains have been under development in Japan for two decades; the newest prototype may exceed 547 kilometers (340 miles) per hour.
These are only a few of the many possible uses for superconductors. Research and development of HTS may still yield many more uses for materials that can carry electricity without resistance. And as today's new technologies move into the marketplace, they will have a great effect on the way we generate, deliver, and use electricity, and on the medical and transportation technologies of tomorrow.