Image: Tel Aviv University
Wiring systems powered by highly efficient superconductors
have long been a dream of science, but researchers have faced such practical
challenges such as finding pliable and cost-effective materials. Now
researchers at Tel Aviv University (TAU) have found a way to make an old idea
new with the next generation of superconductors.
Boaz Almog and Mishael Azoulay working in the group of Prof.
Guy Deutscher at TAU’s Raymond and Beverly Sackler School of Physics and
Astronomy have developed superconducting wires using fibers made of single
crystals of sapphire to be used in high powered cables. Factoring in
temperature requirements, each tiny wire can carry approximately 40 times more
electricity than a copper wire of the same size. They have the potential to
revolutionize energy transfer, says Almog.
High-power superconductor cables take up much less space and
conduct energy more efficiently, making them suitable for deployment across
grids of electricity throughout a city. They will also offer a more effective
method for collecting energy from renewable sources, such as solar and wind
energy. Superconducting wires can also be used for energy storage and enable
devices which enhance grid stability.
Beating the heat
One of the things that make our copper wires inefficient is overheating, Almog
explains. Due to electrical resistance found in the metal, some of the energy
that flows through the cables is cast off and wasted, causing the wires to heat
up. But with superconductors, there is no resistance. A self-contained cooling
system, which requires a constant flow of liquid nitrogen, keeps the wire in
its superconducting state. Readily available, non-toxic, and inexpensive—a
gallon of the substance costs less than a gallon of milk—liquid nitrogen
provides the perfect coolant.
Even with the benefit of liquid nitrogen, researchers were
still hard pressed to find a material that would make the ideal superconductor.
Superconductors coated on crystal wafers are effective but too brittle, says Almog,
and although superconductors on metallic tapes had some success, the product is
too expensive to manufacture in mass quantities.
To create their superconductors, the researchers turned to
sapphire fibers, developed by Amit Goyal, PhD, at the Oak Ridge National Laboratory,
lent to the TAU team. Coated with a ceramic mixture using a special technique,
these single-crystal fibers, slightly thicker than a human hair, have made
Almog is currently working to produce better superconductors that could
transport even larger amounts of electric current.
One area where such superconductors could lend a hand is in
collecting renewable energy sources. “Sources such as wind turbines or
solar panels are usually located in remote places such as deserts or offshore
lines, and you need an efficient way to deliver the current,” explains Almog.
These superconductors can traverse the long distances without losing any of the
energy to heat due to electrical resistance.
Superconducting cables could also be an efficient way to
bring large amounts of power to big cities “If you want to supply current
for a section of a city like New York,
you will need electric cables with a total cross-section of more than one meter
by one meter. Superconductors have larger current capacities using a fraction
of the space,” says Almog. Different parts of a city could be cross-wired,
he adds, so that in the event of a blackout, power can be easily rerouted.