... lemon, orange, grapefruit, apple, and the vegetable potato?
Well here is a page on a lemon powered calculator. Might contain what you need http://funadvice.com/r/bg1asrsbscv And a page in wikipidia with about lemon batteries http://funadvice.com/r/14pnflvkgi8
Here is info about an organge juice clock. http://funadvice.com/r/14pnflvkvep
So yah google has some answers but its not going to spoon feed them to you. You might have to read a bit and do a bit of research. Such a terrible thing.
Umm google is your friend and do your own homework -_-
google wont give me the answer.