Part One: The Electric Grid—Now and in the Future

May 17, 2007 2:08 PM
By Lou Pechi, President, STRATA-Strategic Advisors, San Diego

“The electrical grid goes practically everywhere. It reaches into your home, your bedroom, and climbs right up into the lamp next to your pillow. It’s there while you sleep, and it’s waiting for you in the morning. Taken in its entirety, the grid is a machine, the most complex machine ever made.” —Philip Schewe in his latest book, The Grid.

Think about the pervasiveness of the global electrical network. It is a truly remarkable achievement. Like a gigantic octopus it envelops the whole earth and through its uncountable number of tentacles delivers, just in the United States, over 4 trillion KWh of electricity per year.

Not only does this network deliver such a tremendous amount of energy, it delivers it quite reliably, with an outage of only 8 hours total per year. In technical language, that is approximately 99.9% of uptime per year, more commonly referred to as “three nines” reliability (see the table). For an average household, such availability is adequate, but still results in nuisance outages. The food in the refrigerators will not spoil, but you might have to reset some of the clocks that are not battery backed.

While three nines availability results in just eight hours of outage per year, the grid experiences numerous disruptions due to electrical storms, electromechanical arcing, motor starts, and electrical welders, etc. These perturbances are almost impossible to prevent. For the commercial industry, such availability and line perturbances are simply unacceptable.

While exact calculation of the cost of a power outage varies (and varies for each segment of the industry), hospitals, airport and military installations cannot live with the three nines presently supplied by the power industry and have taken various measures to increase the uptime. Requirements in the telecom and datacom industry start at six nines reliability. However, the present smart chips can crash with power flickers of less than a millisecond. Preventing such fleeting disturbances requires greater than ten nines reliability.

Table. Uptime and Maximum Downtime per Year

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