Silver: the Great Conductor

Of the metals, silver is the best conductor of heat and electricity; consequently, it is used widely throughout industry. Including photographic demand, some 845 million ounces were used in 2000. Since 1990, demand has exceeded production and secondary recovery by 1.39 billion ounces. Now, a recent development appears set to increase demand by 50 million ounces annually within ten years.

The ability to generate and use electricity sets apart First World countries from Third World countries. From generators to transformers, transmission and distribution to motors, wire forms the basic building block of the world's electric power system. The discovery of revolutionary high temperature superconducting (HTS) compounds in 1986 led to the development of a radically new type of wire for the power industry-the most fundamental advancement in wire technology in more than a century.

HTS wire, a ceramic compound made of certain metal oxides that exhibit zero electrical resistance at the temperature of liquid nitrogen (-195 C, -320 F) have now been perfected, and commercial production has begun. Traditional superconductors function only at the temperature of liquid helium (-276 C, -450 F), an expensive gas requiring cumbersome equipment. The higher temperature of liquid nitrogen easily can be maintained by efficient mechanical refrigerators; hence the name, high-temperature superconductors (HTS). HTS wire carries 140 times the electrical current of copper wire and relies on silver for its flexibility, conductivity, and strength.

Silver is the crucial element in HTS because the ceramic core of the wire is brittle. But, when encased in silver, the wire can be drawn out to one-sixteenth the diameter of human hair and can be bundled and wound for use in electric motors. Further, the silver sheathing provides a protective and benign barriers for the ceramic. Silver is the only material that works in this unique application. Studies have shown that the greatest amount of electric current flows in the superconducting oxides where they touch the silver.

Although HTS wire has the potential for multiple applications, two applications appear set to have the greatest impact on electricity, both its delivery and consumption. First, the Department of Energy is spearheading (funding) a national program to increase the efficiency, reliability, and capacity of America's electric power delivery system. The goal is to reduce the nation's reliance on imported oil by reducing transmission losses in conventional distribution systems, which can be as high as 8%. Eventually, though, silver-encapsulated HTS conductors will be incorporated into the complete range of electrical devices from the largest electric motors to toys.

To accelerate the use of HTS products into the commercial sector, the DoE awarded two contracts to prove the practical utility of HTS high-power transmission cables and HTS power transformers. The cable project entails the construction of a 120-meter HTS cable for replacement of existing copper cable at Detroit Edison's Frisbee Station in downtown Detroit. Three HTS cables will replace nine copper cables and will carry the same 100 megawatts of power. This will free up six ducts, which can be used for other assets, such as more HTS cables or telecommunications cables. The cost savings of not having to build more ducts are enormous.

Another project involves a 10-megavolt/amps HTS transformer for installation in a U.S. electric utility grid. An HTS transformer is oil-free and uses environmentally friendly liquid nitrogen to keep it at its operating temperature. At that temperature, HTS transformers lose no power due to resistance heating, and they weigh 30% to 50% less than conventional transformers, permitting increased capacity in smaller spaces. As electrical demands grow, HTS transformers will help deliver that electricity with greater efficiency. The government's interest in HTS wire does not end with the DoE.

The Navy awarded a contract for the preliminary design and component fabrication for a 33,500 horsepower ship propulsion electrical motor, which will use HTS wire. On announcing the contract, Secretary of the Navy Richard Danzig said, "Electric drive will reduce cost, noise, and maintenance demands of how our ships are driven. More importantly, electric drive, like other propulsion changes, will open immense opportunities for reducing vulnerability and allocating a great deal more power to war-fighting applications." The project will begin with sea trials of a prototype ultra-compact 5,000-horsepower motor using HTS wire.

The electric propulsion market should grow rapidly because electric drives have fewer moving parts, and maintenance is reduced, as is the crew required for power-plant support. Most importantly, higher propelling efficiency means lower fuel costs. An HTS motor delivering the same power as a conventional motor can do so at 1/5 the size and 1/3 the weight. These two features provide tremendous benefits to ships, where space and weight are always major considerations.

Although silver-sheathed HTS wire was designed and patented by American Superconductor Corporation of Westborough, Massachusetts, at least three other countries, Denmark, Germany, and China, can produce HTS wires more than 100 meters long, which is necessary for most commercial uses. China was the last to join this elite group; it is not known whether the Chinese developed the technology or pirated it from one of the other countries.

The development of HTS wire is revolutionary, the greatest advancement in wire production in 100 years. Its applications will stretch from motors capable of propelling seagoing ships to tiny toys. Because of HTS, the generation, the delivery, and the storage of electricity will increase significantly, improving our quality of living by reducing fossil fuel needs. And, there is a side point of fascinating implications.

HTS wire replaces copper wire. Approximately 24% of newly mined silver comes from the production of copper. As HTS wire usage becomes widespread, it will reduce the demand for copper. As the demand for copper slackens, so should production. Consequently, use of HTS wire, which is expected to require 50 million ounces annually within a decade, could result in less silver being mined.

Bill Haynes

November 14, 2001

This article is from Monetary Digest, Certified Mint, Inc.'s precious metals newsletter. The author has been a precious metals dealer since 1973. He can be reached at [email protected] His primary Web site iswww.certifiedmint.com