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The Computer and the Dynamo

Brian Hayes

Blackouts were rolling across California last winter when I first began to hear stories about the gluttonous energy appetite of computers, and how Silicon Valley might be partly to blame for the power crisis. Computers and the infrastructure of the Internet, the reports said, were consuming 8 percent of the nation's electricity supply. Or maybe the figure was 13 percent. In any case, by 2010, fully half of all electricity generated in the U.S. would go to keep computer hardware humming.

I first heard these numbers mentioned—without explanation or attribution—in a television newscast. They have turned up in many other places as well, from USA Today and the Wall Street Journal to Computer (the magazine of the IEEE Computer Society). They have been cited in testimony before various Congressional committees. And during the 2000 presidential campaign, George W. Bush quoted the 8 percent figure in a speech on energy policy. His remarks were promptly echoed in a Doonesbury cartoon.

The estimates of computer and network power consumption struck me as quite remarkable. If they were correct, we were approaching a notable inflection point in human affairs, where we expend as much effort in moving information as we do in moving matter. But I had my doubts about those numbers. Bits are so much lighter than atoms. Perhaps a decimal point had slipped out of place. Could it really be true that roughly a tenth of the output of all those gargantuan power plants was being squeezed through the finespun filigree of conductors on silicon chips? It seemed preposterous—but, then again, something like a tenth of all electricity squeezes through the finespun filaments of lightbulbs. The question was not to be answered by mere hand-waving.

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