December 02, 2003
New Superconducting Power Cables Stronger And Cheaper

Next generation superconducting power cables will be able to replace copper cables while increasing the capacity of underground conduits.

New research from the National Institute of Standards and Technology (NIST) suggests that next-generation, high-temperature superconductor (HTS) wire can withstand more mechanical strain than originally thought. As a result, superconductor power cables employing this future wire may be used for transmission grid applications. Projected to become available in three to four years, the advanced superconductor wire (known in the industry as second generation HTS wire) is expected to cost less than the HTS wire used in today's superconductor power cables. The NIST research is described in the Nov. 17 issue of Applied Physics Letters.

Superconductor power cables can carry three to five times the power of conventional copper cables. Compact, underground superconductor cables can be used to expand capacity and direct power flows at strategic points on the electric power grid and can be used in city centers where there is enormous demand, but little space under the streets for additional copper cables. One important challenge in using this next-generation HTS wire in such applications is the need for sufficient strength and resiliency to withstand the stretching and bending that occurs during power cable fabrication and installation.

Using superconductor ceramic coatings on metallic substrates fabricated by American Superconductor Corp. and Oak Ridge National Laboratory, the NIST researchers tested the material's electromechanical properties. According to lead author Najib Cheggour, they found that these advanced wires could stretch almost twice as much as previously believed without any cracking of the superconductor coating and with almost no loss in the coating's ability to carry electricity.

Moreover, the NIST team found that strain-induced degradation of the superconductors' ability to carry electricity is reversible up to a certain critical strain value. That is, the materials return to their original condition once the strain is relieved. The strain tolerance of this future HTS wire was found to be high enough for even the most demanding electric utility applications. The discovered reversible strain effect also opens new opportunities for better understanding of the mechanisms governing the conduction of electricity in this class of superconductors.

I just love it when better living is made possible by advances in materials science.

Share |      Randall Parker, 2003 December 02 02:30 PM  Energy Tech

Kyle Markley said at December 3, 2003 6:56 AM:

"Superconductor power cables can carry three to five times the power of conventional copper cables."

Why is it "only" 3x-5x? What is the limiting factor in power transmission once resistance is gone?

Oleg Dopertchouk said at December 3, 2003 9:52 AM:

:What is the limiting factor in power transmission once resistance is gone?

The electric and magnetic fields. If they get too high, the supercoductivity breaks down. AFAIK Hi-temp superconductors are especially finicky in this aspect

Philip Sargent said at October 15, 2004 8:30 AM:

The actual superconducting tape carries approx. 100x the current density of copper, but the tape is only a small part of the volume of the cable, the rest consists of steel sheath, dielectric, insulation, liquid nitrogen pipe, a load of copper to carry current in case of faults etc. etc.

For AC cables in conventional cable replacement (50Hz in much of the world), there may be no resistance (Ohms law), but there is some energy dissipation. The superconductor's magnetic field has to reverse direction 50x a second and this is called "AC loss" or "superconducting hysteresis loss". Other energy losses are heat leak through the insulation and through the terminations at the ends of the superconductor, and dielectric losses in the material between the conductors. Very roughly the heating effect is 1/3 dielectric, 1/3 AC loss and 1/3 thermal leak. All this heat is at 77K and has to be pumped away using cryogenic refrigeration. The power to do this isn't great, but the capital cost of the cryogenics is painful.

DC cables are a better propostition, but solid state AC/DC converters are expensive and lossy.

mohamed ahmed said at December 11, 2004 11:45 AM:

i want to send me a report on super conducting power transimission cables now plz

useve said at February 8, 2005 9:22 AM:

i want to know about thin film pls, it for my research

24TUBESOFWHUPASS said at August 30, 2009 5:52 AM:

Mohamed Ahmed!

So let me get this straight "Moe!" Are you stating that you're going to send yourself a report of something you haven't a clue as to what it contains??? And you're going to do this now??? I strongly believe that you need to make an appointment with a therapist since you are exhibiting multiple personality as well as control issues within your own personality!!! Be Good to yourself "Moe!"

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