Wired News :Getting to Core of Power Crunch

From human@electronetwork.org (bc)
Date Mon, 4 Jun 2001 10:07:56 -0700 (PDT)

From Wired News, available online at:
http://www.wired.com/news/print/0,1294,44213,00.html

Getting to Core of Power Crunch
By Andy Patrizio

2:00 a.m. June 2, 2001 PDT

LOS ANGELES -- A joint effort between the public and private sectors
addresses one of the overlooked issues in California's power crunch -- the transmission of power.

The project, called InfoWatt, would replace the core wiring used in
power lines from steel to fiber optics -- and thus allow more power to be transported from place to place using existing lines.

The new wiring is vital because even if additional power plants are
brought online, the problem of distribution of the power remains, said Steve Nutt, a USC professor of material science. USC's role in the project was the mechanical testing of design and accelerated aging of equipment to test degradation and analysis.

InfoWatt also would provide needed computer bandwidth to transmit data
between major Internet backbones.

Power lines are made of aluminum on the outside, which carries the
current, and a steel core that supports the wires.

Aluminum is not strong enough to support itself, so the steel core is
necessary. However, steel has drawbacks. It sags in the heat, which causes a loss of transmission capability, and because the steel is so thick, it cuts down on the amount of aluminum used in the wire. Less aluminum means less power capacity.

The lines can't be made thicker, because there is a sweet spot on wire
thickness. If they get too thick, they become subject to environmental stresses such as wind and ice. So wire makers can't add more aluminum thickness to transmit more power.

The solution is to change the core. Southern California Edison, the
University of Southern California and several government agencies have teamed up to create a fiber optic core that is lighter than steel, thinner and can transmit data as well.

"Over the past 20 years, the power industry has boosted production by
30 percent but they’ve only increased the distribution capacity by 15 percent," he said. "There used to be plenty of excess capacity on the grid, but that was when power was generated and sold regionally. With deregulation and shipping power over long distances, it’s taxed the capacity of the grid to carry the amperage."

Power transfer is a major issue facing California. Northern California
has been more prone to blackouts, and while Southern California often has the power to provide the North, it can't get the juice there.

The problem is with the grid, called Path 15, which doesn't have the
throughput.

But building more power lines is an expensive proposition and subject
to the usual NIMBY reaction that Californians are renowned for having. The alternative, said Nutt, is higher capacity wires on the existing towers.

Replacing steel-core wires with fiber allows for more aluminum to be
used in the same thickness wire, since the fiber core is thinner than steel. This means 15 percent more capacity during normal needs and up to 200 percent higher capacity during emergency need.

The new fiber-based wires will be tested on a 222,000-volt line in the
Southern California's Edison grid later this year, and they will require around one year to test, according to Alonso Rodriguez, director of the conductor business unit at Goldsworthy and Associates, a research and development company that worked on the project.

Initial deployments won't take place until 2003, but they can be
rolled out quickly.

"The nice thing about this is you don't have to replace the whole
line, just the lines with sag," Rodriguez said. "For a few hundred thousand dollars you can fix an existing line in a few weeks time so it wouldn't be a bottleneck."

Rodriguez estimates that sag causes a loss of as much as 30,000
megawatts of power.

The secondary benefit to the fiber core will be high-speed data
transmission. Rodriguez estimates the wires will be able to carry several gigabits of data per second. The data transmission aspect has not been a priority in the wiring development, but it has been a consideration.

"I don’t think it would be difficult at all," Nutt said. "There are
some practical issues, like how do you splice the connection and how do you join it at the end?" Another issue is that the connection would have to be strung from the main power lines to smaller, lower-capacity lines.

The InfoWatt wiring will only be used with the largest and highest
capacity wires, so if the core is to be used for data transmission, secondary lines would be needed to branch off from the main power trunks.