What to do with ginger leftover from ginger ale production
I have used excess ginger by candying it- I boil it for about twenty minutes in a simple syrup, when I take the ginger out of the syrup I place it on a cooling grate and let it cool completely. I then roll each individual piece in turbinado sugar(I have used white sugar too.) To store I place it in a plastic bag with a little extra sugar to prevent the pieces from sticking to each other. I also keep the syrup tightly sealed in the freezer, the syrup is great for cocktails, or as a remedy for an upset stomach. 
I have also peeled leftover ginger and stored it in a tightly sealed container inside my freezer. This is convienent because when you need ginger, you can easily grate the frozen ginger for your recipe. Generally you can store it frozen for at least a good three months. Hope this helps.