Complex Electric System Links Power and Disaster

Getting electricity from a distant power plant to the light switch in your kitchen takes less than a second but involves an extraordinarily complex series of steps with multiple opportunities for going astray.

Technicians sitting in control rooms at dozens of utilities and quasi-public regional transmission organizations decide how power should flow through interconnected territories -- with sometimes competing state and federal officials setting the rules.

It all begins at a power plant, where electricity is generated using natural gas, coal, oil, nuclear fission, water or, less frequently, renewable sources such as wind and sun. The electricity travels at the speed of light along miles of inch-thick, high-voltage transmission cables strung from 150-foot metal towers.

Because electricity can’t be stored, transmission operators must maintain a constant balance between supply and demand on this electron freeway, continuously matching the amount of electricity added to the grid with the amount used by customers.

The power then travels to neighborhood substations, where it is reduced in voltage to a level usable by homes and businesses and sent along the local utility’s distribution wires to customers.

Most of the time, the system works without a hitch. But at any step, something can go wrong. A power plant turbine could blow. A wildfire or lightning could fry a transmission line. A computer operator could send too much power to a substation, causing a surge.

While the cause of the massive Northeast blackout remains under investigation, it shows the overworked, aging and interwoven system is vulnerable.

Thursday’s outage “stems from the way in which the transmission system has been planned and developed over the past 20, 30 years,” said Elliot Roseman, a power expert with ICF Consulting. “The grid is kind of like a patchwork quilt.”

North America’s transmission grid has three independent regions: the so-called Eastern interconnection, which covers states east of the Rockies and eastern Canada; the Western interconnection, covering California and 10 other states, as well as part of Baja California, Mexico, and western Canada; and Texas, which stands alone.

North America’s electricity transmission grid began as a local business in 1882 when Thomas Edison introduced electric lights to parts of New York City. Back then, hometown utilities would string wires from their power generators to customers’ homes and businesses.

But enormous growth, particularly since World War II, pushed utilities to build far-flung and interconnected networks of high-voltage wires to move electricity more efficiently and to improve reliability. If a problem developed, a utility could turn to its neighbors for extra juice.

Federal regulators have been pushing utilities in recent years to create regional organizations to improve transmission planning and operation.

But occasionally, as happened Thursday, the mutual-aid model becomes a widespread disaster as safeguards kick in -- from one territory to another -- to shut down overloaded lines and power plants to prevent fires and explosions.

“The system has been doing what it’s designed to do. It’s been tripping,” said Shmuel Oren, director of the Power Systems Engineering Research Center at UC Berkeley. “Once there has been a fault, there have to be disconnections.”

“The systems are linked together, kind of like mountain climbers,” said Jim Letzelter, an electricity expert with Platts, an energy research and consulting firm.

“If one climber falls, because they are linked together, the strong ones hold up the weak and everyone is safe again. But when everything lines up in a real bad way, then the errant mountain climber brings down the whole ball of wax,” Letzelter said.

Energy experts for years have been advocating that more power lines be built. The Edison Electric Institute, a utility trade group, says that transmission investment has been dropping steadily for 25 years. In 2000, the amount of that investment was $2 billion, down from about $5 billion in 1975. At the same time, demand has been growing.

With the advent of deregulation in parts of the country, the responsibility for building power plants and transmission lines is up for grabs. And poor investment returns, significant environmental restrictions and strong community opposition have led to a steady decrease in investment in transmission lines and equipment.

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Staff writer Nancy Vogel contributed to this report.