Superconductor technology can make motors and generators lighter and smaller. Learn how superconductors could significantly impact future warships as well as industrial markets:

Superconductors—materials that will conduct electricity without resistance below a certain temperature—are making their way to the high seas thanks to a $78 million U.S. Navy effort. In fact, the project could propel superconductors to be utilized not only in future warships, but also in cruise ships, the cargo business, and even the electricity-generating industry. The potentially groundbreaking program involves the testing of a 5-MW, 23-ton superconductor ship motor and the design of a full-scale, 36.5-MW superconductor motor. The U.S. Office of Naval Research (ONR) is spearheading the project.

“Superconductor technology will help reduce the size and weight of motors, generators, power transmission and supporting components,” says Rear Admiral Jay M. Cohen, the Chief of Naval Research. Moreover, he believes the technology will help the Navy hasten its transition from mechanical-drive to electric-drive propulsion for its ships.

Superconductors eliminate the resistance that lead to losses in the energy flowing through the material. As a result, they offer tremendous advantages in motors, including more compact designs and lighter weight. In fact, superconductor motors—even with all of their necessary cooling systems—can be nearly 70% smaller and lighter than conventional motors while packing an equal amount of power. This offers a huge advantage to ships, significantly expanding cargo space or ordnance-carrying capabilities. In cruise ships, the superconductor motor’s smaller size could make room for 20 more berths. Additionally, the motor’s efficiency increases by 1 or 2%, depending on the load. This translates to hundreds of thousands of dollars in fuel savings per year for the average cargo ship.

Massachusetts-based American Superconductor Corp. made the superconductor wire that is at the core of these two motors. If the motors perform as expected, they could capture the first big-time application for high-temperature superconductors (HTS), which were discovered and unveiled to the public with much fanfare 17 years ago. While companies such as Sumitomo, Ultera, Pirelli, Southwire and others have assembled and tested superconducting electric transmission cables since the materials’ discovery, commercial sales have been lackluster. Makers of transmission cables have struggled to build them cost-effectively because of the need to cool the cables along their entire length using liquid nitrogen. Keep in mind that while these cables use so-called “high-temperature” superconductors, the term is only relative. They become perfect conductors, shedding all electrical resistance, at temperatures higher than those required by traditional superconductors, but still 173°C below freezing.

Fortunately, in superconductor rotating machines such as motors or generators, cooling needs are not as extensive. Only main rotation-producing components, such as the rotor, require cryocooling. Thus, superconductor motors are extremely promising for cruise ships, which started to switch to electric several years ago. Currently, cruise and cargo vessels represent a $400 million annual market for motors and generators, says maritime consulting company MSCL LLC in Virginia. Greg Yurek, American Superconductor’s CEO, tells IEEE Spectrum that he believes that some commercial ships will be sporting 5-MW HTS motors by the first half of 2005, “about a year after orders are placed.”

And even more lucrative markets could be awaiting superconductors. For example, industrial electric motors—a $1.2 billion-a-year industry—and electrical generators are both a good fit for the technology. With their compact size, light weight and high efficiency, generators with superconducting materials could bring a lot of advantages to these markets. To examine the technology’s feasibility, General Electric Co., in Connecticut, is assembling a 100-MVA superconducting generator under a $12.3 million project sponsored by the U.S. Department of Energy.

Indeed, superconductors could soon be conquering the high seas—and much more. If they prove successful at ongoing tests, they could achieve profitability in both the marine and industrial world.

Source:

Superconductors on the High Seas
Elizabeth A. Bretz
IEEE Spectrum Online, January 2004
www.spectrum.ieee.org/WEBONLY/publicfeature/jan04/0104tran1.html