Staying power

Mobile devices are great – until they run out of power. How can this be prevented?

One of the less pleasant side effects of the revolution in mobile devices over the last two decades has been the all-too-familiar sense of dread that afflicts users when their MP3 player or mobile phone's battery indicator move into the red. Of course, this problem is addressed in many environments. In our cars we now have chargers that keep our devices topped up, while in offices it is far from unusual for visitors to ask to 'steal' some electricity to charge their smartphone or tablet computer. There are even paid-for charging points available in places like motorway service stations and exhibition centres. Nonetheless, places remain where recharging one's device is not possible. For this reason, a number of companies offer battery-powered emergency charger for various devices. However, these have the disadvantage that they must be charged themselves or use disposable batteries. This essentially just moves the problem of maintaining a charge from one place to another rather than actually offering a long-term solution. Another factor militating against these solutions is their environmental impact, with fossil fuels being consumed by a mains-powered charger and chemical batteries having problems relating to disposal, it seems clear that something more sustainable is required. The Challenge Our challenge this month, then, is to device a means whereby your mobile device can be charged renewably and without recourse to another mains-charged device or to chemical batteries. Several possibilities suggest themselves. Solar power, for instance, would seem like a good idea – but for the fact that it relies on there being sunshine, on the photovoltaic unit not being too heavy, cumbersome or – perhaps most importantly of all – expensive. Perhaps another renewable power generation method is the answer, then? Wind power. However, tempting though it is to imagine people walking around with their phone or MP3 player hooked up to a miniature wind turbine kept somewhere about their person. However, it seems fair to suggest that such a solution would not only be rather awkward (and even dangerous), but that it will certainly present something of a challenge in terms of marketing to the general public. A commercially-available solution does exist that uses some ingenious and innovative engineering to achieve this end and we will publish it in our November issue. However, in the mean time, see if you can come up with something better.