Well, global warming is a big problem, but a bigger problem is charging your phone again and again to keep it alive. Even if you are busy with a formal business meeting or you are on a trip with your friends, there is one thing which will keep bugging you and that is your phone and its discharged battery.
What if there was some permanent solution to it! May be there is. Some amazing people have come up with an idea which enables us to charge our phones with our own urine and a pair of socks.