Sunday, July 12, 2015
The U.S. power grid consists of three loosely connected parts, referred to as interconnections: eastern, western and Texas. Within each, high-voltage power lines transmit electricity from generating sources such as coal or hydroelectric plants to local utilities that distribute power to homes and businesses, where lights, refrigerators, computers and myriad other "loads" tap that energy.
Because electricity in power lines cannot be stored, generation and load have to match up at all times or the grid enters blackout territory. That can result from a lack of generating capacity—the cause of the 2000 California blackouts—or because of one or more faults, as in the 2003 blackout. The interconnectedness of the grid makes it easier to compensate for local variations in load and generation but it also gives blackouts a wider channel over which to spread.
On August 14, 2003, shortly after 2 P.M. Eastern Daylight Time, a high-voltage power line in northern Ohio brushed against some overgrown trees and shut down—a fault, as it's known in the power industry. The line had softened under the heat of the high current coursing through it. Normally, the problem would have tripped an alarm in the control room of FirstEnergy Corporation, an Ohio-based utility company, but the alarm system failed.
Over the next hour and a half, as system operators tried to understand what was happening, three other lines sagged into trees and switched off, forcing other power lines to shoulder an extra burden. Overtaxed, they cut out by 4:05 P.M., tripping a cascade of failures throughout southeastern Canada and eight northeastern states.
All told, 50 million people lost power for up to two days in the biggest blackout in North American history. The event contributed to at least 11 deaths and cost an estimated $6 billion.
One of the realizations since 2003 is that "you can't just look at your system. You've got to look at how your system affects your neighbors and vice versa," says Arshad Mansoor, vice president of power delivery and utilization with the Electric Power Research Institute of Palo Alto, Calif.
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Nearly 44 percent of American households don’t have enough savings to cover their basic expenses for three months in the event of a financial emergency like losing a job or paying for unexpected medical care.“These are households and individuals that are living paycheck-to-paycheck. And without savings, you’re one misstep away from financial disaster.”
Many of the Americans living on the financial edge are employed and living a middle-class lifestyle, the report found. Three-quarters are employed full-time and more than 15 percent earn more than $55,000 per year, according to the Assets and Opportunity Scorecard.
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The official poverty rate increased from 12.5% in 2007 to 15.0% in 2012, and the child poverty rate increased from 18.0% in 2007 to 21.8% in 2012.
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Nearly half of Americans, 49.5%, lived in a household where at least one person was receiving some type of government benefit in the fourth quarter of 2012. That number ticked up slightly from 49.2% at the end of 2011.