Wind turbines operate on the same basic principles as a hand-powered generator.

© iStockphoto.com/EdeWolf

Sometimes we take our modern electrical grid for granted, assuming we'll always have easy access to power whenever we need it. But there are quite a few situations where electricity isn't so easy to come by and places where there's no outlet to plug your cell phone charger into. For instance, you might travel into the wilderness (or an emergency might leave you stranded there). In the aftermath of powerful storms, it can take days or even weeks for utility companies to reconnect downed power lines. And there's always the chance that a zombie apocalypse will leave civilization in shambles. The batteries for your gadgets are only going to last so long.

But there's one way to generate electricity that never runs out of power and is easy to carry: a hand-powered generator. It's the travel gadget that can power all your other travel gadgets -- your cell phone, MP3 player, or an emergency radio. In this article, we'll explain how hand-powered generators work and what they can be used for.