SANTA CLARA, Calif. – Improving energy efficiency is the way the electronics industry must go, but it is important to also take a system-level view of issues, according to Professor Jonathon Koomey, recently appointed as research fellow at the Steyer-Taylor Center for Energy Policy and Finance at Stanford University.
Koomey provided a second-day keynote presentation at the ARM TechCon conference and exhibition here that looked at measuring efficiency in electronic systems and then went on to show by anecdotal examples how applications based on distributed sensing and processing could help improve society. One lesson taught by Professor Koomey is that the energy-saving benefits usually come from moving bits rather than atoms.
Professor Koomey started by flattering his audience, saying that they, by being in the audience at ARM TechCon, clearly understand that the major issue going forward is how to build low-powered or self-powered systems.
He also gave them the good news that, to date, miniaturization has yielded not only higher performance transistors but also ones that consume less energy to switch.
He referenced his own work highlighting long-term trends in improving energy efficiency in computing and mobile phones. In the case of computing, there has been a doubling of energy efficiency every 1.5 years throughout the PC era, although the trend line extends back into vacuum tube era. "Since the 1940s there has been a 100x improvement every decade," he said. However, he acknowledged that these plots do not take into account the important issues of system power consumption when idle.
In most systems, idle power consumptions and the speed of transition to and from active mode are more significant than active mode power consumption, he said. "Of course you want to reduce both," he said.
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Professor Jonathon Koomey engages with a packed audience at ARM TechCon.
Professor Koomey also referenced work in progress on improving energy efficiency in cell phones. As with computer function, choosing what to measure is important. Professor Koomey said he has an assistant plotting the efficiency of 500 mobile phones going back to a Motorola unit from 1984, the metric being talk-time per watt-hour. The statistics so far show an improvement of about 8 percent per year, although of course modern cell phones do much more than enable voice calls.