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A Brownout Breakthrough from 3M?

Summertime heat waves are just around the corner, and power troubles won't be far behind. But the factors that determine when utilities have to turn down the juice often have little to do with the physical capacity of their power lines. Rather, it's because as the power load rises, a line droops -- like an overstretched rubber band -- risking failure if it touches tree branches or another line. Engineers at 3M (MMM) think they have got a fix. They're trying out a new composite wire that doesn't sag.

High-voltage lines are typically made up of current-transmitting aluminum wire wrapped around a steel cable for strength. The more electricity passes through a line, the more the steel cable heats up and expands or elongates. Add the summer sun on a hot day, and a line can easily sag so much that it would come dangerously close to other objects -- shorting out the line and causing big-time disruption -- unless the voltage is quickly dialed back.

TECHNOLOGY BOOST. 3M's answer is a strong-as-steel cable made of a ceramic composite of aluminum oxide. Since it barely expands, the material should allow wires to carry two to three times as much juice on peak-demand days, averting possible brownouts or blackouts, says Tracy L. Anderson, a program manager at the St. Paul (Minn.) industrial conglomerate.

3M's new composite power lines costs substantially more than today's steel-core version, Anderson concedes, though he won't say precisely how much. But he points out that a utility might spend even more erecting towers for new high-voltage lines to carry the same load. "It's cost-competitive," he says. Plus, by only stringing new wires on the same poles, a power company may avoid not-in-my-backyard activists, who can easily hold up utility projects for years.

The potential market is huge. Electric-power executives say the country has dozens of chokepoints where lines aren't adequate for peak demand in the summer. And every year, publicly traded utilities spend upward of $3.6 billion to construct or upgrade high-voltage transmission lines, according to the Edison Electric Institute.

GOING COMMERCIAL? 3M has been field-testing its new wire at a half-dozen sites, from North Dakota and Minnesota to Tennessee, Arizona, and Hawaii. Altogether, it has accumulated nine years of data on how they function.

So far, so good, say executives at utilities experimenting with the lines. Indeed, execs at Xcel Energy (XEL) say they're now crunching the numbers for a 230-kilovolt line near their Minneapolis headquarters and hope to decide in June whether to use the new material commercially. If they do, they'll be the first utility to do so. That could be comforting as the nation cranks up the air conditioning in summers ahead. By Michael Arndt in Chicago

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