As a child of the 'seventies, I remember oh to well the disappointment of receiving a wonderful new toy for Christmas or birthday that came in a box with the phrase "Batteries not included". So familiar became the phrase to my generation that Hollywood made a movie of that title.
Today, batteries are almost always included and they are more commonly of the lithium-ion rechargeable type.
While they power our mobile world, they are also the bane of the mobile world. The latest smart phones, running at full speed on Wi-Fi, with Bluetooth, GPS and video enabled can efficiently discharge a device's power pack within a matter of hours. This can have the anxiety-inducing effect of disengaging you from the digital world in an instant, at least until you get back to your home or office to plug in the ubiquitous and never universal charger or a USB cable.
There has been talk of the portable fuel cell, another quaint technology that shares its origins with batteries in the earliest days of nineteenth century electrical science. A fuel cell could use lighter fuel or some other organic chemical energy source to charge up the power pack through the catalytic conversion of that chemical energy to an electron flow. However, as my well-travelled engineer friend Chris Moller, points out, the by-product of fuel cell action is hot water vapour, which isn't great to have around electronic devices - unless you're a hipster steam punk perhaps - even if you have given them the HzO water-repelling treatment.
There are photovoltaic solar chargers available, but these silicon devices are in something of a consumer valley because to make charge times reasonably short they have to have a large area. Moreover, users rely on being able to get outside into bright sunlight, something that is very much lacking on this frozen and foggy January day as I type at my deskbound laptop here on the outskirts of Cambridge, England.
The news, last October [http://onlinelibrary.wiley.com/doi/10.1002/adma.201202196/abstract;jsessionid=B1CB946AB8D323B87ACDEFA95ABCB6DE.d01t02] that South Korean scientists led by Lee Sang-young of South of the Ulsan National Institute of Science and Technology have developed shape-conformable polymer electrolytes for a future generation of flexible, cable-like batteries is good news for designers who might one day be able to discreetly incorporate batteries of almost any shape into whatever shaped gadget. But, I bet those flexi-batteries will have no greater capacity than the current units.
There are hints of super-capacitors and "batteries" that charge in a tiny fraction of the time, minutes instead of hours for a laptop battery, for instance. Nevertheless, it's the charging step, with its requisite need for a power outlet, which almost always limits a user's range.
So, what is to be done? One possible approach is to make the electronics more efficient, to use firmware to cut corners when it comes to processor power, but that is inevitably a compromise and some services like GPS and motors(!) will inevitably drain power units. In reality, the solution lies with the materials scientists, the physicists and engineers and the development of an entirely new way to generate electricity from solid substances. Perhaps waiting to be discovered is a sandwich of substrates that absorbs carbon dioxide from the atmosphere and spits out nothing more than the currency of the digital age, electrons, and does so in perpetuity. Until then, just make sure any batteries that are included are fully charged before you go out to play.
David Bradley blogs at http://www.sciencebase.com and tweets @sciencebase, he is author of the popular science book "Deceived Wisdom".