After concluding that I’d dropped my aging smart phone one too many times, I upgraded to a newer model last month. While appreciating how much faster my new phone is, I’ve been, like many others, displeased at how much faster the battery runs out of power. A report purporting to show that your cell phone uses more electricity than your refrigerator got my attention.
As my new phone can do so many more things than the first “slab” cell phone I acquired at the end of the previous century, it seemed to make sense that it would use far more electricity. But a closer examination of the data and methods of the “phone needs more energy than a fridge” report (pdf) suggests that the intriguing claim is just that.
The claims of the report, “The Cloud Begins With Coal,” rest on mismatched comparisons of data, writes Jonathan Koomey of the Lawrence Berkeley National Lab in the ending summary of an extensive analysis on Think Progress:
One way to support the claim that the electricity use associated with an iPhone is as large (or twice as large) as a refrigerator is to combine the high electricity intensity of 2G/3G cell phone networks with the largest plausible data downloads from 4G networks…. Another way is to use 3G electricity intensities and exaggerate data flows by a factor of 12 (as [the report's author, Mark P. Mills of the Digital Power Group] has done). In either case, the electricity intensity and data flow numbers are inconsistent and incomparable, so the results are nonsensical.
Koomey emphasizes that, in comparing criteria like data flow or electricity, you have to keep in mind that there are “large changes over time [even over a year or two] in the efficiency of information technology (IT) equipment, including mobile phones and the supporting systems.”
Newer devices that use 4G are more efficient in their use of energy than older ones using 2G or 3G. The networks that devices run on have also become more energy efficient so that “simple averages of ‘typical cell phones’ will mislead you.”
In addition, Mills underestimates the energy usage of new refrigerators, Koomey points out. Mills says that these use 350 kilowatt hours/year, without referencing the source of that figure. Citing colleagues at the Lawrence Lab who have studied energy efficiency in refrigerators for thirty years, Koomey says that the average new refrigerator in the U.S. in 2011 used 574 kilowatt hours/year.
With statements about how today’s global digital economy uses as much electricity as it took to light up the planet in 1985, Mills’ report does serve to remind us that, in the effort to live a more sustainable lifestyle, we have become more dependent than ever on wireless technology and on devices that we never turn off.
We absolutely still need to push for the use of wind power, solar power and other forms of green energy; for ways to build energy-efficient structures like those of the passive house movement, in which houses are built with unusually thick walls and other features such that they make “efficient use of the sun, internal heat sources and heat recovery” and require very little energy to cool and heat.
As Koomey underscores, we also have to be careful when reviewing reports about technical issues and look beyond an artfully worded notion (phones that use more energy than refrigerators — can that be true?), review the facts and figures and realize that researchers, knowing how central digital devices are to our life, are working to make them more efficient.
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