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February 5, 2003: Few technologies
ever enjoy the sort of rock-star celebrity that superconductors
received in the late 1980s.
Headlines the world over trumpeted the discovery of "high
temperature" superconductors (abbreviated HTS), and the
media and scientists alike gushed over the marvels that we could
soon expect from this promising young technology. Levitating
300-mph trains, ultra-fast computers, and cheaper, cleaner electricity
were to be just the beginning of its long and illustrious career. Above: The MLX01 experimental "maglev" train, currently being tested
by Japan's Railway
Technical Research Institute, uses "old fashioned"
low-temperature superconductors that require liquid helium for
a coolant. High-temperature superconductors can use liquid nitrogen
instead, which is cheaper, more abundant, and easier to handle.
Image courtesy RTRI. Today we might ask, like a Hollywood gossip columnist: what
ever happened to the "high-temp" hype? "It was the hottest potato of its time, but it all
fizzled out," says Louis Castellani, president of the Houston-based
HTS company Metal Oxide Technologies, Inc. (MetOx).
The problem was learning to make wire out of it. These superconductors
are made of ceramics--the same kind of material in coffee mugs.
Ceramics are hard and brittle. Finding an industrial way to make
long, flexible wires out of them was going to be difficult. Indeed, the first attempts were disappointing. So-called "first
generation" HTS wire was relatively expensive: 5 to 10 times
the cost of copper wire. Furthermore, the amount of current it
could carry often fell far short of its potential: only 2 or
3 times that of copper, versus a potential of more than 100 times. But now, thanks to years of research involving experiments
flown on the space shuttle, this is about to change. Left: "Second generation" HTS wire can carry the same amount
of current as copper wire hundreds of times as thick. Image courtesy
MetOx. The NASA-funded Texas Center for Superconductivity and Advanced
Materials (TcSAM) at the University of Houston is teaming with
MetOx to produce the "smash hit" that scientists have
been seeking since the '80s: a "second generation"
HTS wire that realizes the full 100-fold improvement in current
capacity over copper yet costs about the same as copper to produce.
Once-famous superconductors may be about to step back into
the limelight. The audience awaits The special "talent" of superconductors is that
they have zero resistance to electric current. Absolutely none.
In theory, a loop of HTS wire could carry a circling current
forever without even needing a power source to keep it going. In normal conductors, such as copper wire, the atoms of the
wire impede the free flow of electrons, sapping the current's
energy and squandering it as heat. Today, about 6 to 7% of the electricity generated in the United
States gets lost along the way to consumers, partly due to the
resistance of transmission lines, according to U.S. Energy Information
Agency documents.
Replacing these lines with superconducting wire would boost utilities'
efficiencies, and would go a long way toward curbing the nation's
greenhouse gas emissions. The fledgling "maglev"
train industry would also welcome the availability of higher-quality,
cheaper HTS wire. Economic realities stalled the initial adoption
of maglev transit systems, but maglev development is still strong
in Japan, China, Germany, and the United States. Right: MRI scans, a powerful tool for medical diagnosis,
use superconducting electromagnets to generate detailed images
of body tissues. Most of today's MRI machines require expensive
liquid helium to cool their low-temperature superconducting wire.
NASA is looking at how superconductors could be used for space.
For example, the gyros that keep satellites oriented could use
frictionless bearings made from superconducting magnets, improving
the satellites' precision. Also, the electric motors aboard spacecraft
could be a mere 1/4 to 1/6 the size of non-superconducting motors,
saving precious volume and weight in the spacecraft's design.
Should we ever establish a base on the moon, superconductors
would be a natural choice for ultra-efficient power generation
and transmission, since ambient temperatures plummet to 100 K
(-173 C, -280 F) during the long lunar night--just the right
temperature for HTS to operate. And during the months-long journey
to Mars, a "table top" MRI machine made possible by
HTS wire would be a powerful diagnosis tool to help ensure the
health of the crew. Worldwide, the current market for HTS wire is estimated to
be US$30 billion, according to Castellani, and it is expected
to grow rapidly. A backstage pass The University of Houston has licensed this new wire-making
technology to MetOx, a company founded in 1997. MetOx plans to
begin full-scale production of this high-quality HTS wire in
2003, Castellani says. Not surprisingly, the primary scientist for the NASA group
at TcSAM, Dr. Alex Ignatiev, can't reveal exactly how they make
their HTS wire. The technologies springing from these NASA/industry
research partnerships must be patented to achieve NASA's goal
of using space to benefit American businesses, Ignatiev says. He will, however, share the dinner-napkin sketch. Basically, the wire is made by growing a thin film of the
superconductor only a few microns thick (thousandths of a millimeter)
onto a flexible foundation. This well-known production method
was improved upon in part through "Wake
Shield" experiments flown on the space shuttle to learn
about growing thin films in the hard vacuum of space. Left: The Wake
Shield Facility being held out in space by the shuttle's
robot arm. Image courtesy NASA. "We learned how to grow higher-quality oxide thin films
from the shuttle experiments, and used that in the lab to improve
the quality of our superconducting films," Ignatiev says. In the years to come, that quality will translate into improvements
in dozens of industries from power generation to medical care.
Keep an eye on this one: the glamorous career of superconductors
has only just begun. | 
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