Forgot your iPhone charger? If you're not too thirsty, just add water.
PowerTrekk, a portable system that uses water to generate hydrogen-based electricity, can re-charge a dying phone even if it is miles away from an outlet.
The system uses hydrogen cartridges, which contain a chemical that begins to produce energy when mixed with water. The cartridges, called PowerPukks, are biodegradable and disposable. Developed as an offshoot of a program to bring electricity to underdeveloped rural areas, outdoor goods haven REI will sell the kit for around $200, with hydrogen cartridges running around $3.
It would take an astronomical hike in natural gas prices to make the technology feasible for larger-scale projects, so for now, PowerTrekk's source of energy is best for extreme situations for individual users.
Meanwhile, the U.S. Army is developing cloth that charges smartphones. These innovations demonstrate a demand for alternative ways to charge electronics, especially as they become linchpins for professional and military communication in areas without easy access to traditional power sources.
Those systems are likely less cumbersome than carrying around a PowerTrekk box, but the PowerTrekk box is extremely efficient, which may make it the best bet for use in emergencies -- as long as a the user can reach a viable water source.
Each cartridge will re-charge a depleted iPhone two times, and can power LED lights for weeks at a time, which could be crucial to an outdoor sports enthusiast in an emergency. The situation James Franco's character experienced in the film "127 Hours", for example, when he got trapped while hiking without a way to get into contact with anyone, would have turned out to be more like 3 or 4 hours if he'd carried the PowerTrekk.