Aluminum plays a major role in the lives of
the people charged with building and maintaining the country's
electric grid. Besides being cost-effective, aluminum cable has
the conductivity and mechanical properties needed for overhead
"Aluminum conductors are the backbone of the
world's overhead transmission system," said Eric Engdahl,
principal engineer of transmission line asset engineering at
American Electric Power Co. Inc. (AEP) in Columbus, Ohio.
"Aluminum combines the strength and conductivity required for
overhead lines. At AEP, aluminum is the material of
In transmission applications, there is a
continuing market for aluminum conductor cable as the nation
builds up the electric grid. "From all indicators I see,
consumption will continue at least at present levels," Engdahl
Aluminum cable manufacturers are sold out,
suggesting a robust level of demand, one source said.
"You'll see new transmission capacity being
overlaid as an addition to the existing grid," Engdahl said,
looking ahead. "You will also see local additions to serve the
ever-increasing needs of localities."
There also will be a great deal of
refurbishing, reconfiguration and rebuilding of existing
systems. "You'll see a tremendous push across the country to
refurbish what is a massive infrastructure," he said. Much of
this activity will involve aluminum components.
Engdahl did not provide estimates for the
cost and scope of such projects, but 2005 projections for
upgrading the U.S. power grid to meet projected demand-roughly
2 percent per year-by the end of this decade ranged from a low
of $27 billion to as much as $100 billion, although these
figures included power generation as well as transmission.
So far, power grid growth has never met
projected demand, falling roughly 30 percent short on an annual
basis, according to the North American Electric Reliability
Upgrading an existing transmission line can
cost upwards of $1 million per mile, and building a new line
can cost two to three times as much for the same distance, an
industry source said, although he cautioned that the large
number of variables in any transmission line project makes
generic cost estimates unreliable.
Mike Hervey, vice president of operations for
the Long Island Power Authority (Lipa), also sees aluminum
playing a major role as transmission capacity is added. "We
definitely have ongoing plans for building additional overhead
transmission lines," he said, adding that Lipa spends between
$20 million and $40 million annually on new transmission lines,
most of which will use aluminum conductors.
In addition to being less expensive than
copper, aluminum also is more durable, Hervey said. Aluminum
also can be a choice for underground lines, he added, in places
where overhead lines are impractical or otherwise unsuitable.
"In high-capacity transmission, copper is almost always
outpriced by aluminum," he said. Since aluminum is close to
one-third the price of copper, aluminum cable-often sold on a
commodity basis-can provide substantial savings.
Consolidated Edison Inc., responsible for
powering New York City, also uses aluminum conductors for
overhead transmission lines, a company spokesman said. Aluminum
conductors have sufficient current-carrying capacity and
structural strength for long spans, he said, such as wide water
crossings where towers cannot be built or other areas where
rights of way cannot be secured for new towers. Aluminum is
light in weight, easy to handle and companion hardware is
easily available, he said. "We have not encountered any major
problem with aluminum conductors for overhead transmission
Both AEP and Lipa have considered new
composite core cables, saying it offers certain solutions not
possible with conventional cables.
"The composite core cable has low thermal
expansion properties, which mitigates line sag due to thermal
expansion," Engdahl said. "The design allows you to use the
conductivity of the aluminum to a greater extent."
The new cable "allows you to increase power
flow in a short time and at a reasonable cost over an existing
right of way" using existing towers, Engdahl said. "Such
retrofitting is where I see the advantage of the composite core
Hervey also sees the composite core design as
a niche product because it costs three times as much as
traditional steel-reinforced aluminum cable. "We have looked at
the composite core material and the price differential, which
puts it in the area of special uses, where span length and
higher capacity are issues," he said. "For example, if you had
a large water crossing where you can't build towers, it makes
perfect sense to use the composite core cable."