fyi
Date: Tue Dec 22 1998 14:02
LGB (SILVER.... and Superconductivity) ID#269409:
Copyright © 1998 LGB/Kitco Inc. All rights reserved
Superconductivity... yet one more use for Silver..intially to the tune of perhaps 30
million ounces per annum. Hopefully, climbing from there.
Silver is a key component of superconductors soon to be used in several major
electric power demonstrations, which could change the future of energy distribution
throughout the world and require substantial quantities of silver in the coming years.
Superconductivity is a phenomenon first discovered in 1911 in which electricity
flows without resistance through some materials if cooled to extremely cold
temperatures. Ordinary conductors such as copper or aluminum present resistance
to the flow of electric current, causing energy to be lost during transmission. Cables
made with superconducting wires can carry three to five times more current than
conventional copper wires.
Because superconductors transmit electricity without resistance, electrical equipment
can be smaller, lighter and
more powerful, as well as more efficient. Applications are being developed and
implemented in a wide array of
markets, including electric utility equipment, high-energy physics, diagnostic medical
magnetic resonance
imaging, and electronics applications such as filters for cellular base stations.
Prior to 1986, all known superconductors were normally operated below -411oF,
and thus are called
low-temperature superconductors ( LTS ) . Such low operating temperatures are
difficult and expensive to create
and maintain, and therefore, have found limited and highly specialized applications.
In 1986, researchers discovered certain ceramic oxide materials that superconduct
at temperatures much higher than the conventional LTS.
Today, the most common method of making HTS wires begins by producing
precursor powders, according to a U.S. Department of Energy ( DOE ) Report,
published in July 1998, entitled “At the Frontiers of Science:
Superconductivity and its Electric Power Applications.” The powders are loaded
into a silver cylinder which is welded closed. The cylinder is drawn to wire, cut,
stacked into a second cylinder, drawn to wire again, and rolled to form a
multifilamentary tape. The powders are comprised of four to seven chemical
elements which are subjected, between rolling steps, to a series of heat treatments.
The temperature at which the material inside the cylinder becomes superconducting
is known as the transition or critical temperature which vary depending on the
material.
Agrrement to construct an HTS cable that will power several facilities owned b
Southwire Company, the largest cable manufacturer in the United States.
Intermagnetics General Corporation, a world leader in the development and
manufacture of superconducting systems, will develop and manufacture the HTS
material to be installed in the
12,500 volt, 1,250-ampere HTS electric cable.
All practical methods for manufacturing HTS wires use silver as a sheath for several
reasons. First, silver is highly ductile and can be shaped around the superconducting
material which is as brittle as blown glass. As a noble metal, silver does not react
with the superconductor, and silver is permeable to oxygen and highly conductive.
Although silver is an expensive material to use as a sheath, “nobody has found a
suitable substitute for this type of HTS superconductor,” said Carl Rosner, chairman
and CEO of Intermagnetics. “So far, silver is the only material that prevents
deterioration of the superconducting properties.”
Rosner explained that HTS wire is still in the development stage, and said that to
make the technology commercially viable, costs must be “reduced by a factor of five
or ten.” The expense of silver is always a target, he explained, but costs also can be
cut in the fabrication process and other superconducting component materials.
“Right now we're obviously just involved in building this one test line,” Rosner said.
Hypothetically speaking, once the test is successful, he said “and if we were to
replace the transmission line grid in the United States with this technology, it would
require enormous quantities of silver — possibly as much as 1000 kilograms per
mile.”
In addition to the Intermagnetics project, DOE also is expected to fund five
additional demonstrations this year through its Superconductivity Partnership
Initiative. Two of the projects would focus on building HTS
transformers, while another would build a 120-meter cable system to be installed in
the existing power network of Detroit Edison company. A fourth project would
develop a reciprocating magnetic separator and a fifth would design a flywheel
energy storage system based on existing HTS bearing technology. Altogether, the
projects could receive up to $47 million from DOE with industry partners
contributing at least 50 percent of total project costs.
DOE's superconductivity initiative is part of the agency's plan for the United States
to regain a major share of the global market for electric power systems by 2010.
Through the increased use of HTS devices, DOE officials hope to boost domestic
productivity and efficiency, especially in industries that are large users of electricity.
The global HTS industry is composed of about 50 companies acting as suppliers of
raw materials and developers/producers of wires, tapes and components, according
to a recent study by Business Communications
Company, Inc. The United States is now the leading testing and application
developer of these materials.
“We are preparing for a profound change in the way electricity is generated,
delivered and used,” says Jim Daley, manager of DOE's superconductivity program
for electric power systems.
Applications incorporating HTS technology are poised to explode into the market
over the next 10 years impacting electronics, transportation, medicine and many
other industries as well, the DOE report says. Industry
experts project that the entire market for superconductor products and services
could reach $200 billion by 2020. For silver, that could mean more than 30 million
ounces annually in the early stages, with significant growth potential as the industry
matures.
“Because the demand for electricity is expected to double by the year 2030, the
introduction of superconductors into everyday use is critical to meeting those future
demands,” Daley said.
The DOE report compares superconductivity to fiber optics which revolutionized
the communications industry, and also to transistors without which digital watches
and personal computers would not exist. “The capacity of these discoveries to
transform our world far surpassed any applications we could have dreamed of,” the
report says. “Superconductivity too, will surely continue to fuel our imaginations.” |
