On the second day of CESAsia, Tom Coughlin of the IEEE Consumer Electronics Society painted a grim picture of conventional mobile power technology. Based on trends to date, Coughlin estimates that the energy density of batteries is doubling only every 10 years, while Moore’s Law doubles the transistor count for CPUs every 18 months or so.
The result is an widening mismatch between what we’d like to do with mobile devices and what we can do. For example, according to Coughlin’s analysis, getting a smartphone’s battery to last a full week between charges, the way the ones powering old cellphones used to do, would require between 26 and 104 times the amount of energy typically stored by the batteries in today’s handsets. At the current lethargic pace of battery technology development, it would take decades to get a battery with enough juice to be an adequate match for the phone that sits in your pocket or purse right now, waiting for a recharge.
And that’s not even accounting for some of the power-hungry things we like to try with our phones, from computational imaging that could make the image sensors on today’s phones look like pinhole cameras, or continuous life logging.
In a valiant attempt to play catch-up, the Consumer Electronics society is pushing a new initiative in hopes of rapidly improving the power sources available for mobile devices: the Safe Advanced Mobile Power initiative.
The technical requirements for the ideal future power source the society envisions boil to these: In addition to providing enough energy, it has to be cost efficient, scaling with manufacturing volume so that by the time we’re knocking out this source by the hundred million, the unit cost should be no more than around US $20. It also has to be safe, and not likely to result in deaths either among users or among those employed in extracting and processing the raw materials. That’s a tall order, but it’s definitely worth a shot.
It’s entirely possible that battery technology will never get to where we need it to be for mobile devices. With that in mind, there are three alternatives to batteries that may someday usurp their dominance. The first is fuel cells, which various people have been trying to incorporate into things like laptops for a while now. The second is energy harvesting, sipping power from mechanical or thermal sources of energy in the environment. Last but not least is wireless power, whereby energy would be transmitted to mobile devices through the air. Recently, wireless has become increasingly popular as a way to recharge the batteries in mobile devices. But if wireless charging’s market share is to ever reach parity with that of batteries, improvements aimed at making it more useful will have to be made. More consumers will clamor for it once the range over which it works is extended and the amount of energy that can be transmitted over the air is increased.
If we can’t solve this power problem, then mobile devices are always going to be pale shadows of what they could really be.
Stephen Cass is the special projects editor at IEEE Spectrum. He currently helms Spectrum's Hands On column, and is also responsible for interactive projects such as the Top Programming Languages app. He has a bachelor's degree in experimental physics from Trinity College Dublin.