I’ve spent the past decade of my professional life working to enable connectivity everywhere with Wi-Fi. Back when I started working with Wi-Fi, it was a way of connecting laptops to the network more easily. These days, Wi-Fi is more likely to be used as a way of getting an entirely new type of device connected — a phone, tablet, or even a sensor or automation device.
The downside to all this mobile computing is that batteries are not keeping up with the demands placed on them. Computing power grows exponentially, following Moore’s Law, but the ability of batteries to store energy grows much more slowly. To take one example, the battery capacity of the various models of iPhone have grown about 15% since its introduction, but the increase in the capabilities of the device has far exceeded that mere 15% growth.
Engineers working on battery technology continue to eke out gains, and the energy storage capability of lithium rechargeable batteries is high. According to one memorable turn of phrase, the energy density of lithium batteries is now comparable to hand grenades, even if it is only about 4% of the density of gasoline.
Even with all the work put into battery development, the basic problem remains that we are trying to make the linear growth of batteries serve the exponentially growing demands for power.
Problems with mobile computing are just the most visible limit batteries place on us. I have resigned myself to carrying external USB battery packs to keep my devices charged while on the go. I charge external batteries at night, and then if necessary, I’ll “top off” my phone or other device throughout the day from an external battery pack. In essence, I have capitulated to the small capacity of my devices by carrying around a general-purpose reserve battery.
Problems with mobile devices, though, are only the tip of the iceberg. Electric and hybrid vehicles depend on batteries. “Smart grid” techniques like storing energy generated in off-peak hours for later use need to put the energy somewhere. If I could pick just one energy problem to solve, it would be the humble battery. Until then, I’ll keep carrying around external battery packs while I hope for a leap in technology.