Superconductors ready to ramp up for the real world

The Energizer bunny has nothing on Heike Kamerlingh Onnes. Nearly a century ago, the Dutch physicist stunned the scientific world when he discovered that if he chilled certain metals to extremely low temperatures, electricity raced through them without losing any energy.

There was just one catch: The metals had to be frozen to such frigid temperatures that the technology made no commercial sense.

More recent discoveries led to some niche applications. But today, researchers are on the cusp of applying that laboratory curiosity to a range of civilian and military technologies. They could dramatically boost the efficiency of everything from Navy destroyers to the wires that bring electricity into homes and businesses.

Superconductors - as Onnes' discovery is known - are being tested as a way to dramatically cut the risk of widespread blackouts.

"It's going to work; it's really going to work," says an enthusiastic Robert Hawsey, director of the Oak Ridge National Laboratory's Superconductivity Technology Center. Fiber optics took 20 years to emerge from the lab to become the backbone of today's information superhighway, he notes. After nearly 20 years of development, a new generation of superconductors are about to emerge from the shadows into large-scale applications.

Superconductors have a number of properties that endear them to high-tech visionaries. They have virtually no electrical resistance. In principle, once electricity begins flowing in a superconducting loop, it can flow almost forever. They carry larger amounts of electricity than standard wires and cables with similar dimensions. So superconducting components can be far smaller than their conventional counterparts.

For example, a conventional electric motor for driving a single Navy destroyer propeller might weigh as much as 200 tons, notes Scott Littlefield, director of ship science and technology at the Office of Naval Research (ONR) in Arlington, Va. A superconducting motor, in contrast, would tip the scales at 75 tons.

And superconductors don't lose their electricity to heat. Thus a superconducting motor or computer chip is vastly more efficient than its conventional counterpart.

But there are drawbacks. Superconductors are more finicky than standard electrical components. If the current it carries or the magnetic field it encounters is too strong, a superconductor turns into a mundane conductor faster than Cinderella's coach reverted to a pumpkin.

Then, there's the problem with refrigeration. To get his superconductor to work, Onnes used liquid helium at 4 Kelvin (4 degrees C) above absolute zero - the point where molecules stop moving. By the mid-1980s, traditional superconductors had moved into niche markets. But the high cost of cooling them to liquid-helium temperatures was a stumbling block to broader applications.

Then in 1986, two researchers at IBM's labs in Zurich pulled an Onnes of their own, discovering a ceramic compound that lost its resistance to electricity at a relatively balmy 35 degrees above absolute zero.

Their work set off a frenzy of research. Within weeks, other teams announced ceramic materials that became superconductors at 94 degrees above absolute zero - warm enough that they could be cooled with less expensive liquid nitrogen.

Since then, other ceramic materials have been discovered that become superconductors at more than 130 degrees above absolute zero (white hot, relatively speaking, for the superconductor world, but still 140 degrees below water's freezing point).

But these materials presented a big challenge: How to turn the ceramic into a wire.

Firms such as American Superconductor in Massachusetts and Japan's Sumitomo Electric, cleared that hurdle by designing tape-like "wires" for use in cables, motors, and devices that help utilities smooth the bumps in electricity they supply.

The Tennessee Valley Authority, for example, is testing a device built by American Superconductor that helps the grid maintain stable voltage on the lines. If successful, the utility plans to install five of the devices. "So far, we're very pleased with the test results," says Terry Boston, TVA's executive vice president for the transmission and power supply group.

The Navy also has been a driver behind several developments in the field. It is testing one of two prototype superconducting motors it funded - a 5,000 horsepower device built by American Superconductor. A second design using conventional metal superconductors is being built by General Atomics in Torrey Pines, Calif.

In the mid-90's, the Navy took a page from the cruise-ship industry and began to hitch its propeller shafts to electric motors rather than to gas turbines - particularly on destroyers. Turbines would still be needed to generate electricity. But electric motors would spin the props.

In order for the Navy to devote more of a ship's volume to people, weapons, and electronics, "we need to get motors as compact as you can," says the ONR's Mr. Littlefield. Superconducting motors may be the answer.

Once the motor technology is in hand, the same approaches can be used to build compact superconducting generators. Those can be used to power a new generation of weapons aboard ships and aircraft, notes Florida State University researcher Steinar Dale. So-called rail guns, for example, use magnetic fields to hurl a nonexplosive projectile at speeds where its impact alone is explosive. By some estimates, a 30-inch-long rail-gun projectile could deliver up to eight times the energy in 1/10th the travel time as extended-range munitions currently under development.

Similar techniques could be applied in a less souped-up form to launch aircraft from carriers, notes Dr. Dale.

Civilian and military prototypes tested so far have been built around so-called first-generation wire. Soon, the first batch of second-generation wire - with significantly better electrical, magnetic, and mechanical properties and cheaper production costs - will be moving onto spools. American Superconductor plans to ship its first production-grade second-generation wire within the next six to nine months, says chief executive Greg Yurek. Others, including Sumitomo, are nipping at his heels.

Even before so-called 2G wire hits the streets, the push is on to develop third-generation wire that aims for even lower production costs and better performance. The reasoning is simple: "You'd better eat your own lunch, because if you don't, your competitors surely will," notes Dr. Yurek, taking a page from former Intel chief Andrew Grove.

Superconductivity is on the verge of moving into large-scale applications. Eventually, they could be used in:

• Magnetic-levitation trains. Strong superconducting magnets would be smaller and waste far less energy than conventional electromagnets.

• Supercomputers. Tiny superconductor switches might help computers attain speeds of one-thousand-trillion operations per second.

• E-bombs. Superconductor-derived magnetic fields create a pulse to disable electronic gear. Such a device was used in 2003 when US forces attacked an Iraqi broadcast facility.

Source: Superconductors.org