Yes, an orange can be a battery — and it's

There's plenty of talk about alternative energy options out there, but this battery powered by an orange has to be one of the more interesting attempts at it. The result is pretty cool looking to boot.
The orange battery was created by photographer Caleb Charland, who has made a project out of using fruits and veggies — and other objects — to create light as the subjects of his photography.
The electricity powering the bulb hidden in the center of the segments comes from the chemical reaction between the citric acid in the orange and the zinc nails in the segment.
As you might expect, the power coming from an orange and a few nails isn't going to be enough for it to be your new light fixture. The amount of light produced from this experiment is so low that the photo you see here is the result of a 14-hour exposure.
Even if it isn't a scientific breakthrough, it is a pretty cool little experiment on generating energy and an otherworldly example of long exposure photographyE, with a little steampunk style thrown in.

source: http://dvice.com/archives/2012/11/yes-an-orange-c.php