The Green Corollary to Moore's Law

Hang around with technologists for long-enough, and you're sure to hear mention of Moore's Law, a once-precise empirical observation about how semiconductor components were shrinking. Over the years, Moore's Law has come to mean something like, "Computers double in speed every one-and-a-half years," which has been the case during the personal computing era, or roughly the last 35 years. In just the last week, Google News indexed 138 stories mentioning the Law. And, needless to say, that underlying phenomenon has transformed the way the world works. 

But there's a little-known but very important parallel movement to Moore's Law recently elucidated by Jonathan Koomey, an energy specialist at Stanford and Lawrence Berkeley National Laboratory. Koomey went back into the historical record and found that the electrical efficiency of computing has been increasing at the roughly the same pace as computing speed. Let's call it Koomey's Corollary to Moore's Law

"The electrical efficiency of computation (measured in computations per kilowatt-hour, or kWh) grew about as fast as performance for desktop computers starting in 1975, doubling every 1.5 years, a pace of change comparable to that from 1946 to the present," Koomey wrote with co-authors in a paper released earlier this year. 

And if you're not sure why this is important, think back to the last time your phone ran out of batteries when you needed to make a call or you wished your laptop could last just another hour. Improvement in the electrical efficiency of processing is one of the ways those dreams will come true. (Batteries are the other biggie, and electric car promoter, Project Better Place's Shai Agassi, claims his own Moore's Law corollary, declaring "every five years, you need half as much lithium to create the same battery.")

It's not just personal computers that benefit for doing more calculations per kilowatt hour of electricity. The server farms and supercomputers that crunch Big Data are less expensive to run and less taxing on the environment. Just take a look at the latest version of the Green 500 list of the world's most energy efficient supercomputers, which was released last month. The computer atop its rankings, the Grape-DR at the University of Tokyo, can do 815 million calculations per second (FLOPS) with just one watt of electrical input. (Although it should be noted that computing is really not the main problem, environmentally.)

You can hear Koomey describe his data acquisition (and a whole lot more) in a fascinating lecture he delivered at Berkeley.

Image: The Grape DR supercomputer. Credit: National Astronomical Observatory of Japan.
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Alexis C. Madrigal

Alexis Madrigal is the deputy editor of He's the author of Powering the Dream: The History and Promise of Green Technology. More

The New York Observer has called Madrigal "for all intents and purposes, the perfect modern reporter." He co-founded Longshot magazine, a high-speed media experiment that garnered attention from The New York Times, The Wall Street Journal, and the BBC. While at, he built Wired Science into one of the most popular blogs in the world. The site was nominated for best magazine blog by the MPA and best science website in the 2009 Webby Awards. He also co-founded Haiti ReWired, a groundbreaking community dedicated to the discussion of technology, infrastructure, and the future of Haiti.

He's spoken at Stanford, CalTech, Berkeley, SXSW, E3, and the National Renewable Energy Laboratory, and his writing was anthologized in Best Technology Writing 2010 (Yale University Press).

Madrigal is a visiting scholar at the University of California at Berkeley's Office for the History of Science and Technology. Born in Mexico City, he grew up in the exurbs north of Portland, Oregon, and now lives in Oakland.

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