Koomey's Law: Computer Processor Efficiency not Power doubles every 18 months.

And yet we still grow impatient with current battery technology.

The conclusion, backed up by six decades of data, mirrors Moore’s law, the observation from Intel founder Gordon Moore that computer processing power doubles about every 18 months. But the power-consumption trend might have even greater relevance than Moore’s law as battery-powered devices—phones, tablets, and sensors—proliferate.

“The idea is that at a fixed computing load, the amount of battery you need will fall by a factor of two every year and a half,” says Jonathan Koomey, consulting professor of civil and environmental engineering at Stanford University and lead author of the study. More mobile computing and sensing applications become possible, Koomey says, as energy efficiency continues its steady improvement.