HTS alliance

American Superconductor and Northrop Grumman have formed a business alliance to sell, market and develop products for the US military based on high temperature superconductor (HTS) wire.

American Superconductor and Northrop Grumman Marine Systems yesterday entered a strategic business alliance to sell, market and develop products for the US military based on high temperature superconductor (HTS) wire. The joint sales and marketing effort will focus initially on HTS electric propulsion motors for the US Navy.

The six-year alliance covers development of HTS propulsion systems, energy storage and conversion, transformers and pulse-power applications.

Superconductors are materials that conduct electricity without resistance below a certain temperature. The only commercial application until recently was in medical magnetic resonance imaging (MRI) devices, which utilise low temperature superconductor (LTS) wires.

In 1986, Swiss scientists discovered a new family of superconducting materials that still require cooling to cryogenic temperatures, but that operate at 5 to 20 times higher temperatures than the old LTS materials. The new materials, which are ceramic compounds, have become known as high temperature superconductors (HTS).

According to American Superconductor, the lower cost of cooling these new materials significantly enhanced the commercial economics of superconductor applications, and created the possibility of using high power density superconducting wires in power cables, motors and generators.

HTS technology is said to offer significant advantages to the military in terms of power density and higher electrical efficiency. HTS motors measure as little as one-third the weight and one-half the size of copper-based motors of the same power and torque rating. In addition, HTS motors operate with higher fuel efficiency and have lower maintenance costs than their conventional copper counterparts.

Currently, the two companies are collaborating on development of a 36.5-MW (49,000 horsepower), 120 rpm HTS ship propulsion motor under contract to the US Navy’s Office of Naval Research. The companies are also working together to qualify this advanced motor design as an alternative to conventional motors and other advanced motor designs.

The development of a 36.5-MW HTS motor follows American Superconductor’s successful demonstration in September 2004 of a prototype 5-megawatt (MW) High Temperature Superconductor (HTS) ship propulsion motor. The motor ran at full load, under steady state operational conditions, at the Center for Advanced Power Systems (CAPS) at Florida State University in Tallahassee.