Just a few years ago, a typical cell phone would let you make calls, send and receive text messages, and perhaps allow you to surf a text-based Web page. Today, smartphones come packed with features. You may be able to play games, listen to music, navigate to an address, surf the Web and activate one of a million different apps. But all this functionality can tax your phone's power supply. While a cell phone from a decade ago might have lasted several days on a single charge, a smartphone may not be able to make it through more than a day without the need for more juice.
This might not be a big problem if you always have a charger at hand and a way to plug your phone into a power supply. But if you're on the go and you can't plug your phone into an electrical socket or a computer's USB port, you may be in need of other options. You could carry extra batteries with you so that you can swap them out on the fly, but that just increases the number of batteries you need to charge each day.
You have other options. There are products on the market that convert kinetic energy into electricity. But what if you don't want to crank for half an hour in order to send a text? There are also solutions that harness solar power to help you recharge your electronics. But then you have to hope for a sunny day to take advantage of them.
What about fuel cells? Like a battery, a fuel cell uses a chemical reaction to generate electricity. But unlike a battery, you can refuel a spent fuel cell. Just add a bit more fuel, and you're ready to generate more electricity. Hydrogen fuel cells only produce two byproducts -- heat and water. The fuel cells we'll use to charge our portable electronics are more likely to rely on fuels like butane.