Do not listen to the person who said NO NO NO, they do not know what they are talking about. You can produce electricity using soda cans, but not JUST soda cans. You will need:
4 empty soda cans 4 pencils 4 pieces of wire tap water table salt tape
fill each soda can as full as you like with tap water, and then add salt (more salt will result in better conductivity). Break off the erasers from all the pencils so that you can see the lead on both ends, and place them in the soda cans so that one end is in the salt water, and the other end is sticking up out of the can. Using tape, attach one end of a piece of wire to the pencil inside a can (so that the wire is touching the lead), and the other end to the next soda can. Continue this until all the soda cans are linked pencil-to-can in this way (you don't have to use 4 of everything, just the same number. Congratulations, you've just made a battery! The voltage will not be very high (.25V~1V), but you are producing electricity. You can test this by attaching a voltmeter in lieu of one of the pieces of wire.